/* ============================================
Backend Developer Learning Platform
Complete CSS Design System
============================================ */

/* ============================================

1. CSS Variables & Design Tokens
============================================ */
:root {
    /* Primary Color Palette */
    --primary-50: #eff6ff;
    --primary-100: #dbeafe;
    --primary-200: #bfdbfe;
    --primary-300: #93bbfc;
    --primary-400: #60a5fa;
    --primary-500: #3b82f6;
    --primary-600: #2563eb;
    --primary-700: #1d4ed8;
    --primary-800: #1e40af;
    --primary-900: #1e3a8a;


    /* Secondary Color Palette (Success/Green) */
    --secondary-50: #ecfdf5;
    --secondary-100: #d1fae5;
    --secondary-200: #a7f3d0;
    --secondary-300: #6ee7b7;
    --secondary-400: #34d399;
    --secondary-500: #10b981;
    --secondary-600: #059669;
    --secondary-700: #047857;
    --secondary-800: #065f46;
    --secondary-900: #064e3b;

    /* Accent Color Palette (Warning/Amber) */
    --accent-50: #fffbeb;
    --accent-100: #fef3c7;
    --accent-200: #fde68a;
    --accent-300: #fcd34d;
    --accent-400: #fbbf24;
    --accent-500: #f59e0b;
    --accent-600: #d97706;
    --accent-700: #b45309;
    --accent-800: #92400e;
    --accent-900: #78350f;

    /* Danger Color Palette (Red) */
    --danger-50: #fef2f2;
    --danger-100: #fee2e2;
    --danger-200: #fecaca;
    --danger-300: #fca5a5;
    --danger-400: #f87171;
    --danger-500: #ef4444;
    --danger-600: #dc2626;
    --danger-700: #b91c1c;
    --danger-800: #991b1b;
    --danger-900: #7f1d1d;

    /* Neutral Color Palette (Gray) */
    --neutral-50: #f8fafc;
    --neutral-100: #f1f5f9;
    --neutral-200: #e2e8f0;
    --neutral-300: #cbd5e1;
    --neutral-400: #94a3b8;
    --neutral-500: #64748b;
    --neutral-600: #475569;
    --neutral-700: #334155;
    --neutral-800: #1e293b;
    --neutral-900: #0f172a;

    /* Semantic Colors */
    --background-primary: #ffffff;
    --background-secondary: var(--neutral-50);
    --background-tertiary: var(--neutral-100);
    --background-dark: var(--neutral-800);
    --background-code: #282c34;
    --background-code-alt: #1e1e1e;

    --text-primary: var(--neutral-900);
    --text-secondary: var(--neutral-600);
    --text-tertiary: var(--neutral-500);
    --text-inverse: #ffffff;
    --text-link: var(--primary-600);
    --text-link-hover: var(--primary-700);

    --border-default: var(--neutral-200);
    --border-hover: var(--neutral-300);
    --border-focus: var(--primary-500);

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-success: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --gradient-warm: linear-gradient(135deg, #fa709a 0%, #fee140 100%);

    /* Typography */
    --font-system: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'Fira Code', 'JetBrains Mono', 'Consolas', 'Courier New', monospace;

    --font-size-xs: 0.75rem;    /* 12px */
    --font-size-sm: 0.875rem;   /* 14px */
    --font-size-base: 1rem;     /* 16px */
    --font-size-lg: 1.125rem;   /* 18px */
    --font-size-xl: 1.25rem;    /* 20px */
    --font-size-2xl: 1.5rem;    /* 24px */
    --font-size-3xl: 1.875rem;  /* 30px */
    --font-size-4xl: 2.25rem;   /* 36px */
    --font-size-5xl: 3rem;      /* 48px */

    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    --line-height-loose: 2;

    /* Spacing */
    --spacing-xs: 0.25rem;   /* 4px */
    --spacing-sm: 0.5rem;    /* 8px */
    --spacing-md: 1rem;      /* 16px */
    --spacing-lg: 1.5rem;    /* 24px */
    --spacing-xl: 2rem;      /* 32px */
    --spacing-2xl: 3rem;     /* 48px */
    --spacing-3xl: 4rem;     /* 64px */

    /* Layout */
    --sidebar-width: 300px;
    --sidebar-collapsed-width: 60px;
    --header-height: 60px;
    --container-max-width: 1200px;
    --content-max-width: 900px;

    /* Border Radius */
    --radius-sm: 0.25rem;    /* 4px */
    --radius-md: 0.375rem;   /* 6px */
    --radius-lg: 0.5rem;     /* 8px */
    --radius-xl: 0.75rem;    /* 12px */
    --radius-2xl: 1rem;      /* 16px */
    --radius-full: 9999px;

    /* Shadows */
    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.06);
    --shadow-colored: 0 10px 40px -15px rgba(102, 126, 234, 0.4);

    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;

    /* Z-index Scale */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;


}

/* Dark Theme Variables */
[data-theme="dark"] {
    --background-primary: var(--neutral-900);
    --background-secondary: var(--neutral-800);
    --background-tertiary: var(--neutral-700);
    --text-primary: var(--neutral-100);
    --text-secondary: var(--neutral-400);
    --text-tertiary: var(--neutral-500);
    --border-default: var(--neutral-700);
    --border-hover: var(--neutral-600);
    --shadow-sm: 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
}

/* ============================================
2. Reset & Base Styles
============================================ */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-system);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    background: var(--gradient-primary);
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

.auth-gate {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.75);
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
}

.auth-gate-card {
    background: var(--background-primary);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-2xl);
    max-width: 420px;
    width: 100%;
    text-align: center;
    box-shadow: var(--shadow-2xl);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.auth-gate-card h2 {
    margin-bottom: 0;
}

.auth-gate-card p {
    color: var(--text-secondary);
    margin-bottom: 0;
}

/* ============================================
3. Typography
============================================ */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-semibold);
    line-height: var(--line-height-tight);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
}

h2 {
    font-size: var(--font-size-3xl);
}

h3 {
    font-size: var(--font-size-2xl);
}

h4 {
    font-size: var(--font-size-xl);
}

h5 {
    font-size: var(--font-size-lg);
}

h6 {
    font-size: var(--font-size-base);
}

p {
    margin-bottom: var(--spacing-md);
    line-height: var(--line-height-relaxed);
}

a {
    color: var(--text-link);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--text-link-hover);
    text-decoration: underline;
}

strong {
    font-weight: var(--font-weight-semibold);
}

em {
    font-style: italic;
}

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background: var(--background-tertiary);
    padding: 0.125rem 0.25rem;
    border-radius: var(--radius-sm);
    color: var(--danger-600);
}

pre {
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    line-height: var(--line-height-normal);
    overflow-x: auto;
}

/* ============================================
4. Layout Components
============================================ */
.app-container {
    display: flex;
    min-height: 100vh;
    background: var(--background-primary);
    position: relative;
    box-shadow: var(--shadow-2xl);
    max-width: 1600px;
    margin: 0 auto;
}

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    background: var(--background-dark);
    color: var(--text-inverse);
    position: fixed;
    height: 100vh;
    left: 0;
    top: 0;
    z-index: var(--z-fixed);
    display: flex;
    flex-direction: column;
    transition: transform var(--transition-normal);
    overflow-y: auto;
    overflow-x: hidden;
}

.sidebar-header {
    padding: var(--spacing-lg);
    background: rgba(0, 0, 0, 0.2);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    position: sticky;
    top: 0;
    z-index: 10;
    backdrop-filter: blur(10px);
}

.sidebar-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-md);
}

.sidebar-content {
    flex: 1;
    padding: var(--spacing-md);
}

.auth-controls {
    margin-top: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.auth-state {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-sm);
}

.auth-user {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-inverse);
}

.auth-user-text {
    display: flex;
    flex-direction: column;
    line-height: 1.2;
}

.auth-greeting {
    font-size: var(--font-size-xs);
    letter-spacing: 0.05em;
    text-transform: uppercase;
    opacity: 0.75;
}

.auth-name {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
}

.auth-avatar {
    width: 32px;
    height: 32px;
    border-radius: var(--radius-full);
    object-fit: cover;
    border: 2px solid rgba(255, 255, 255, 0.25);
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: var(--sidebar-width);
    padding: var(--spacing-2xl);
    max-width: var(--content-max-width);
    width: 100%;
    animation: fadeIn 0.5s ease;
}

.content-header {
    margin-bottom: var(--spacing-2xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--border-default);
}

.content-title {
    font-size: var(--font-size-4xl);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-sm);
}

.content-subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
}

/* ============================================
5. Components
============================================ */

/* Progress Bar */
.progress-container {
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    height: 8px;
    overflow: hidden;
    position: relative;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--secondary-500) 0%, var(--secondary-400) 100%);
    border-radius: var(--radius-full);
    transition: width var(--transition-slow);
    position: relative;
    overflow: hidden;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.3) 50%,
    rgba(255, 255, 255, 0) 100%
    );
    animation: shimmer 2s infinite;
}

.progress-text {
    font-size: var(--font-size-sm);
    margin-top: var(--spacing-sm);
    opacity: 0.9;
    display: flex;
    justify-content: space-between;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    line-height: 1;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn:active {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

.btn-primary {
    background: var(--primary-600);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-700);
}

.btn-secondary {
    background: var(--secondary-600);
    color: white;
}

.btn-secondary:hover {
    background: var(--secondary-700);
}

.btn-accent {
    background: var(--accent-600);
    color: white;
}

.btn-danger {
    background: var(--danger-600);
    color: white;
}

.btn-outline {
    background: transparent;
    color: var(--primary-600);
    border: 2px solid var(--primary-600);
}

.btn-outline:hover {
    background: var(--primary-600);
    color: white;
}

.btn-ghost {
    background: transparent;
    color: var(--text-primary);
}

.btn-ghost:hover {
    background: var(--background-secondary);
}

.btn-gradient {
    background: var(--gradient-primary);
    color: white;
    font-weight: var(--font-weight-semibold);
}

.btn-large {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-lg);
}

.btn-small {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: var(--font-size-sm);
}

.btn-icon {
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: var(--radius-full);
}

.btn-group {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

/* Cards */
.card {
    background: var(--background-primary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: all var(--transition-normal);
}

.card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-4px);
}

.card-header {
    padding: var(--spacing-lg);
    background: var(--background-secondary);
    border-bottom: 1px solid var(--border-default);
}

.card-body {
    padding: var(--spacing-lg);
}

.card-footer {
    padding: var(--spacing-lg);
    background: var(--background-secondary);
    border-top: 1px solid var(--border-default);
}

/* Exercise Container */
.exercise-container {
    background: var(--background-secondary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    border: 2px solid var(--border-default);
    transition: all var(--transition-normal);
}

.exercise-container:hover {
    border-color: var(--primary-200);
    box-shadow: var(--shadow-md);
}

.exercise-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.exercise-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--primary-700);
}

.exercise-status {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
}

.exercise-status.pending {
    background: var(--accent-100);
    color: var(--accent-900);
}

.exercise-status.in-progress {
    background: var(--primary-100);
    color: var(--primary-900);
}

.exercise-status.completed {
    background: var(--secondary-100);
    color: var(--secondary-900);
}

/* Exercise Enhancements */
.exercise-hints {
    margin: var(--spacing-md) 0;
    background: var(--background-primary);
    border-radius: var(--radius-lg);
    border: 1px dashed var(--primary-200);
    padding: var(--spacing-md);
}

.exercise-hints summary {
    cursor: pointer;
    font-weight: var(--font-weight-medium);
    color: var(--primary-600);
}

.hint-list {
    margin-top: var(--spacing-sm);
    list-style: disc inside;
    color: var(--text-secondary);
}

.hint-list li {
    padding: var(--spacing-xs) 0;
}

.multiple-choice {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.choice-option {
    display: grid;
    grid-template-columns: 24px auto;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    border: 2px solid var(--border-default);
    border-radius: var(--radius-lg);
    cursor: pointer;
    background: var(--background-primary);
    transition: all var(--transition-fast);
}

.choice-option:hover {
    border-color: var(--primary-300);
    box-shadow: var(--shadow-sm);
}

.choice-option input {
    display: none;
}

.choice-marker {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    border: 2px solid var(--border-default);
    display: flex;
    align-items: center;
    justify-content: center;
    background: white;
    transition: all var(--transition-fast);
}

.choice-option input:checked + .choice-marker {
    border-color: var(--secondary-500);
    background: var(--secondary-500);
    color: white;
}

.choice-option input:checked + .choice-marker::after {
    content: '✓';
    color: white;
    font-size: var(--font-size-sm);
    line-height: 1;
}

.choice-option input:checked ~ .choice-text {
    font-weight: var(--font-weight-medium);
    color: var(--secondary-700);
}

.choice-text {
    color: var(--text-primary);
}

/* Code Blocks */
.code-block {
    background: var(--background-code);
    color: #abb2bf;
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    overflow-x: auto;
    margin: var(--spacing-md) 0;
    position: relative;
    line-height: var(--line-height-relaxed);
}

.code-block.interactive {
    border: 2px solid var(--primary-500);
    background: var(--background-code-alt);
}

.code-block pre {
    margin: 0;
    white-space: pre-wrap;
}

/* Code Syntax Highlighting */
.keyword { color: #c678dd; font-weight: var(--font-weight-semibold); }
.string { color: #98c379; }
.comment { color: #5c6370; font-style: italic; }
.function { color: #61afef; }
.number { color: #d19a66; }

/* Pseudocode Specific Highlighting - Higher specificity to override base styles */
.code-block.pseudocode {
    background: #2a2d35 !important;
    border-left: 4px solid #4dabf7;
    border-radius: var(--radius-lg);
    color: #ffffff !important;
    font-size: 0.95rem !important;
    padding: var(--spacing-lg);
    margin: var(--spacing-md) 0;
    font-family: var(--font-mono);
    overflow-x: auto;
    position: relative;
}

.code-block.pseudocode pre {
    line-height: 1.9;
    margin: 0;
    color: inherit;
}

.code-block.pseudocode code {
    background: transparent;
    padding: 0;
    color: inherit;
    font-size: inherit;
}

/* Pseudocode keyword highlighting */
.code-block.pseudocode .pseudo-keyword {
    color: #ff7b7b !important;
    font-weight: 700;
    text-transform: uppercase;
    background: rgba(255, 123, 123, 0.15);
    padding: 2px 8px;
    border-radius: 4px;
    display: inline-block;
    letter-spacing: 0.8px;
    margin: 0 2px;
}

.code-block.pseudocode .comment {
    color: #7f8c9b !important;
    font-style: italic;
    opacity: 0.8;
}

.code-block.pseudocode .string {
    color: #ffd93d !important;
    background: rgba(255, 217, 61, 0.08);
    padding: 1px 4px;
    border-radius: 3px;
}

.code-block.pseudocode .number {
    color: #6bcf7f !important;
    font-weight: 600;
}

.code-block.pseudocode .function {
    color: #74c0fc !important;
    font-style: normal;
    font-weight: 500;
}
.operator { color: #56b6c2; }
.class-name { color: #e06c75; }
.variable { color: #e06c75; }
.boolean { color: #d19a66; }
.pseudo-keyword {
    color: #e5c07b;
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
}

.run-button {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    background: var(--secondary-600);
    color: white;
    border: none;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.run-button:hover {
    background: var(--secondary-700);
    transform: scale(1.05);
}

.code-output {
    background: #1a1d23;
    color: var(--secondary-400);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    margin-top: var(--spacing-md);
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    display: none;
    border-left: 3px solid var(--secondary-500);
}

.code-output.active {
    display: block;
    animation: slideDown 0.3s ease;
}

.routine-simulator {
    margin-top: var(--spacing-md);
    background: var(--background-code);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.routine-simulator .btn {
    margin-bottom: var(--spacing-sm);
}

.routine-output {
    background: rgba(20, 23, 31, 0.7);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    color: #cfd3dc;
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.routine-message {
    font-weight: var(--font-weight-medium);
    color: #f6b17a;
}

.routine-message[data-state="success"] {
    color: var(--secondary-300);
}

.routine-message[data-state="error"] {
    color: #ff8989;
}

.routine-message[data-state="warning"] {
    color: #f6b17a;
}

.routine-canvas {
    position: relative;
    width: 100%;
    min-height: 260px;
    border-radius: var(--radius-md);
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.05);
    background: linear-gradient(180deg, rgba(24, 27, 34, 0.9), rgba(11, 13, 20, 0.95));
}

/* Logic Primer Cards */
.logic-primer .concept-card {
    background: rgba(59, 130, 246, 0.05);
    border: 1px solid rgba(59, 130, 246, 0.2);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin: var(--spacing-md) 0;
}

.logic-primer .concept-card h6 {
    color: var(--primary-600);
    margin: 0 0 var(--spacing-sm) 0;
    font-size: 1.1rem;
}

.code-example-inline {
    background: var(--background-code);
    color: #e9ecef;
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    font-family: var(--font-mono);
    font-size: 0.9rem;
    margin: var(--spacing-md) 0;
    border-left: 3px solid var(--primary-500);
}

.tip {
    background: rgba(251, 191, 36, 0.15);
    border-left: 3px solid var(--accent-400);
    padding: var(--spacing-sm) var(--spacing-md);
    margin: var(--spacing-md) 0;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-primary);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.practice-note {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.1), rgba(59, 130, 246, 0.1));
    border: 2px dashed var(--primary-400);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    margin: var(--spacing-lg) 0;
    font-size: 1.05rem;
}

/* Exercise Instruction Formatting */
.exercise-steps {
    background: rgba(59, 130, 246, 0.03);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.exercise-steps h6 {
    color: var(--primary-600);
    margin: var(--spacing-md) 0 var(--spacing-sm) 0;
    font-size: 1rem;
    font-weight: var(--font-weight-semibold);
}

.exercise-steps h6:first-child {
    margin-top: 0;
}

.exercise-steps p {
    color: var(--text-secondary);
    margin: var(--spacing-sm) 0;
    padding-left: var(--spacing-lg);
}

.template-box {
    background: rgba(16, 185, 129, 0.05);
    border: 2px dashed var(--secondary-400);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
}

.template-box h6 {
    color: var(--secondary-600);
    margin: 0 0 var(--spacing-md) 0;
    font-size: 1rem;
}

.template-code {
    background: var(--background-code);
    color: #e9ecef;
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    font-family: var(--font-mono);
    font-size: 0.9rem;
    overflow-x: auto;
    border-left: 3px solid var(--secondary-500);
    white-space: pre;
}

.template-hint {
    color: var(--secondary-600);
    font-size: 0.9rem;
    margin-top: var(--spacing-md);
    font-style: italic;
}

/* Alerts */
.alert {
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    margin: var(--spacing-md) 0;
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
    animation: fadeIn 0.3s ease;
}

.alert-icon {
    flex-shrink: 0;
    width: 24px;
    height: 24px;
}

.alert-content {
    flex: 1;
}

.alert-title {
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-xs);
}

.alert-info {
    background: var(--primary-50);
    color: var(--primary-900);
    border-left: 4px solid var(--primary-500);
}

.alert-success {
    background: var(--secondary-50);
    color: var(--secondary-900);
    border-left: 4px solid var(--secondary-500);
}

.alert-warning {
    background: var(--accent-50);
    color: var(--accent-900);
    border-left: 4px solid var(--accent-500);
}

.alert-danger {
    background: var(--danger-50);
    color: var(--danger-900);
    border-left: 4px solid var(--danger-500);
}

/* Concept Cards */
.concept-card {
    background: var(--gradient-primary);
    color: white;
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    margin: var(--spacing-lg) 0;
    box-shadow: var(--shadow-colored);
    position: relative;
    overflow: hidden;
}

.concept-card::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: rotate 20s linear infinite;
}

.concept-card-content {
    position: relative;
    z-index: 1;
}

.concept-card h4 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-md);
    color: white;
}

.concept-card p {
    opacity: 0.95;
    line-height: var(--line-height-relaxed);
}

.concept-actions {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.reflection-summary {
    background: rgba(255, 255, 255, 0.12);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    margin-top: var(--spacing-md);
    backdrop-filter: blur(6px);
}

.reflection-meta {
    font-size: var(--font-size-xs);
    letter-spacing: 0.05em;
    text-transform: uppercase;
    opacity: 0.8;
    margin-bottom: var(--spacing-sm);
}

.reflection-item {
    margin-bottom: var(--spacing-sm);
    line-height: var(--line-height-relaxed);
}

.reflection-item:last-child {
    margin-bottom: 0;
}

.reflection-empty {
    font-style: italic;
    opacity: 0.8;
}

/* Forms */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-primary);
    font-size: var(--font-size-sm);
}

.form-input,
.form-textarea,
.form-select {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--background-primary);
    border: 2px solid var(--border-default);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-base);
    color: var(--text-primary);
    transition: all var(--transition-fast);
}

.form-input:hover,
.form-textarea:hover,
.form-select:hover {
    border-color: var(--border-hover);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
    outline: none;
    border-color: var(--primary-500);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-textarea {
    min-height: 120px;
    resize: vertical;
    font-family: inherit;
}

.form-select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%23475569' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right var(--spacing-sm) center;
    background-size: 20px;
    padding-right: var(--spacing-2xl);
}

.form-checkbox,
.form-radio {
    width: 20px;
    height: 20px;
    margin-right: var(--spacing-sm);
    cursor: pointer;
}

.form-help-text {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    margin-top: var(--spacing-xs);
}

.form-error {
    font-size: var(--font-size-sm);
    color: var(--danger-600);
    margin-top: var(--spacing-xs);
}

/* Navigation */
.nav-week {
    margin-bottom: var(--spacing-sm);
}

.nav-week-header {
    padding: var(--spacing-md) var(--spacing-lg);
    background: rgba(255, 255, 255, 0.05);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-radius: var(--radius-lg);
    transition: all var(--transition-fast);
    user-select: none;
}

.nav-week-header:hover {
    background: rgba(255, 255, 255, 0.1);
}

.nav-week-header.active {
    background: var(--primary-600);
}

.nav-week-header .chevron {
    transition: transform var(--transition-fast);
    font-size: var(--font-size-sm);
}

.nav-week-header.expanded .chevron {
    transform: rotate(180deg);
}

.nav-week-days {
    margin-top: var(--spacing-xs);
    padding-left: var(--spacing-md);
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-normal);
}

.nav-week-days.expanded {
    max-height: 500px;
}

.nav-day {
    padding: var(--spacing-sm) var(--spacing-md);
    margin: var(--spacing-xs) 0;
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition-fast);
    position: relative;
    color: rgba(255, 255, 255, 0.8);
}

.nav-day:hover {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    padding-left: var(--spacing-lg);
}

.nav-day.active {
    background: rgba(255, 255, 255, 0.15);
    color: white;
    border-left: 3px solid var(--accent-500);
}

.nav-day.completed::after {
    content: '✓';
    position: absolute;
    right: var(--spacing-md);
    color: var(--secondary-400);
    font-weight: var(--font-weight-bold);
}

/* Python Console */
.python-console {
    background: var(--background-code-alt);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    margin: var(--spacing-md) 0;
    font-family: var(--font-mono);
    border: 2px solid var(--primary-500);
}

.console-header {
    color: var(--secondary-400);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-sm);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.console-history {
    max-height: 300px;
    overflow-y: auto;
    margin-bottom: var(--spacing-sm);
}

.console-line {
    margin: var(--spacing-xs) 0;
    line-height: var(--line-height-relaxed);
}

.console-prompt {
    color: var(--secondary-400);
    margin-right: var(--spacing-xs);
}

.console-input-wrapper {
    display: flex;
    align-items: center;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: var(--spacing-sm);
}

.console-input {
    background: transparent;
    border: none;
    color: #4ec9b0;
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    flex: 1;
    outline: none;
    padding: var(--spacing-xs);
}

.console-output {
    color: #d4d4d4;
    margin-left: var(--spacing-lg);
}

.console-error {
    color: var(--danger-400);
    margin-left: var(--spacing-lg);
}

/* Checklist */
.checklist {
    list-style: none;
    padding: 0;
}

.guided-checklist {
    margin: var(--spacing-lg) 0;
    padding: var(--spacing-lg);
    background: var(--background-primary);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-default);
    box-shadow: var(--shadow-sm);
}

.guided-checklist h4 {
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-lg);
    color: var(--primary-700);
}

.checklist-item {
    padding: var(--spacing-md);
    margin: var(--spacing-sm) 0;
    background: var(--background-primary);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    border: 2px solid var(--border-default);
    user-select: none;
}

.checklist-item:hover {
    background: var(--background-secondary);
    transform: translateX(4px);
}

.checklist-item.checked {
    background: var(--secondary-50);
    border-color: var(--secondary-300);
}

.checklist-item.checked .checklist-text {
    text-decoration: line-through;
    color: var(--text-secondary);
}

.checklist-checkbox {
    width: 24px;
    height: 24px;
    border: 2px solid var(--border-default);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: all var(--transition-fast);
}

.checklist-item.checked .checklist-checkbox {
    background: var(--secondary-500);
    border-color: var(--secondary-500);
}

.checklist-item.checked .checklist-checkbox::after {
    content: '✓';
    color: white;
    font-weight: var(--font-weight-bold);
}

/* Tooltips */
.tooltip {
    position: relative;
    display: inline-block;
    cursor: help;
}

.tooltip-trigger {
    border-bottom: 1px dotted var(--text-secondary);
}

.tooltip-content {
    visibility: hidden;
    opacity: 0;
    position: absolute;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--neutral-900);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    white-space: nowrap;
    z-index: var(--z-tooltip);
    pointer-events: none;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-lg);
}

.tooltip-content::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 6px solid transparent;
    border-top-color: var(--neutral-900);
}

/* Modal */
.modal {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.6);
    display: none;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
    z-index: var(--z-modal);
}

.modal.visible {
    display: flex;
}

.modal-content {
    background: var(--background-primary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    max-width: 500px;
    width: 100%;
    position: relative;
    box-shadow: var(--shadow-2xl);
}

.modal-close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    background: transparent;
    border: none;
    font-size: var(--font-size-2xl);
    cursor: pointer;
    color: var(--text-secondary);
}

.modal h2 {
    margin-bottom: var(--spacing-md);
}

.modal textarea {
    width: 100%;
    min-height: 120px;
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    border: 2px solid var(--border-default);
    margin-bottom: var(--spacing-md);
    font-family: var(--font-system);
    font-size: var(--font-size-base);
    resize: vertical;
}

.modal-actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
}

.modal-open {
    overflow: hidden;
}

.tooltip:hover .tooltip-content {
    visibility: visible;
    opacity: 1;
    transform: translateX(-50%) translateY(-5px);
}

/* Mobile Menu Toggle */
.menu-toggle {
    display: none;
    position: fixed;
    top: var(--spacing-md);
    left: var(--spacing-md);
    z-index: var(--z-fixed) + 1;
    background: var(--primary-600);
    color: white;
    width: 48px;
    height: 48px;
    border-radius: var(--radius-full);
    border: none;
    cursor: pointer;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-fast);
}

.menu-toggle:hover {
    background: var(--primary-700);
    transform: scale(1.1);
}

.menu-toggle:active {
    transform: scale(0.95);
}

/* Welcome Screen */
.welcome-screen {
    text-align: center;
    padding: var(--spacing-3xl);
    max-width: 800px;
    margin: 0 auto;
    animation: fadeIn 0.5s ease;
}

.welcome-title {
    font-size: var(--font-size-5xl);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-lg);
    animation: slideDown 0.6s ease;
}

.welcome-description {
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    line-height: var(--line-height-relaxed);
    margin-bottom: var(--spacing-2xl);
    animation: slideUp 0.6s ease;
}

.welcome-features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-2xl) 0;
}

.welcome-feature {
    padding: var(--spacing-lg);
    background: var(--background-secondary);
    border-radius: var(--radius-xl);
    transition: all var(--transition-normal);
    animation: fadeIn 0.8s ease backwards;
}

.welcome-feature:nth-child(1) { animation-delay: 0.1s; }
.welcome-feature:nth-child(2) { animation-delay: 0.2s; }
.welcome-feature:nth-child(3) { animation-delay: 0.3s; }
.welcome-feature:nth-child(4) { animation-delay: 0.4s; }

.welcome-feature:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.start-journey-btn {
    background: var(--gradient-primary);
    color: white;
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-normal);
    animation: pulse 2s infinite;
}

.start-journey-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-colored);
}

/* Loading States */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 200px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-default);
    border-top-color: var(--primary-500);
    border-radius: var(--radius-full);
    animation: spin 1s linear infinite;
}

.skeleton {
    background: linear-gradient(
    90deg,
    var(--neutral-200) 25%,
    var(--neutral-100) 50%,
    var(--neutral-200) 75%
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
}

.skeleton-text {
    height: 1em;
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-sm);
}

.skeleton-title {
    height: 2em;
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-md);
    width: 60%;
}

/* ============================================
6. Animations
============================================ */
@keyframes fadeIn {
from {
    opacity: 0;
}
to {
    opacity: 1;
}
}

@keyframes slideDown {
from {
    opacity: 0;
    transform: translateY(-20px);
}
to {
    opacity: 1;
    transform: translateY(0);
}
}

@keyframes slideUp {
from {
    opacity: 0;
    transform: translateY(20px);
}
to {
    opacity: 1;
    transform: translateY(0);
}
}

@keyframes slideLeft {
from {
    opacity: 0;
    transform: translateX(20px);
}
to {
    opacity: 1;
    transform: translateX(0);
}
}

@keyframes slideRight {
from {
    opacity: 0;
    transform: translateX(-20px);
}
to {
    opacity: 1;
    transform: translateX(0);
}
}

@keyframes spin {
from {
    transform: rotate(0deg);
}
to {
    transform: rotate(360deg);
}
}

@keyframes shimmer {
from {
    background-position: -200% 0;
}
to {
    background-position: 200% 0;
}
}

@keyframes pulse {
0%, 100% {
    transform: scale(1);
}
50% {
    transform: scale(1.05);
}
}

@keyframes rotate {
from {
    transform: rotate(0deg);
}
to {
    transform: rotate(360deg);
}
}

@keyframes bounce {
0%, 100% {
    transform: translateY(0);
}
50% {
    transform: translateY(-10px);
}
}

@keyframes wave {
0%, 100% {
    transform: rotate(0deg);
}
25% {
    transform: rotate(20deg);
}
75% {
    transform: rotate(-20deg);
}
}

/* ============================================
7. Responsive Design
============================================ */
@media (max-width: 1200px) {
:root {
    --sidebar-width: 260px;
}
}

@media (max-width: 768px) {
.menu-toggle {
    display: flex;
}


.sidebar {
    transform: translateX(-100%);
}

.sidebar.active {
    transform: translateX(0);
}

.main-content {
    margin-left: 0;
    padding: var(--spacing-lg);
    padding-top: calc(var(--spacing-lg) + 60px);
}

.content-title {
    font-size: var(--font-size-3xl);
}

.welcome-screen {
    padding: var(--spacing-xl);
}

.welcome-title {
    font-size: var(--font-size-3xl);
}

.welcome-features {
    grid-template-columns: 1fr;
}

.btn-group {
    flex-direction: column;
}


}

@media (max-width: 480px) {
:root {
    --font-size-base: 0.875rem;
}


.main-content {
    padding: var(--spacing-md);
    padding-top: calc(var(--spacing-md) + 60px);
}

.content-title {
    font-size: var(--font-size-2xl);
}


}

/* ============================================
8. Utility Classes
============================================ */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.font-bold { font-weight: var(--font-weight-bold); }
.font-semibold { font-weight: var(--font-weight-semibold); }
.font-medium { font-weight: var(--font-weight-medium); }
.font-normal { font-weight: var(--font-weight-normal); }

.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-tertiary { color: var(--text-tertiary); }
.text-danger { color: var(--danger-600); }
.text-success { color: var(--secondary-600); }
.text-warning { color: var(--accent-600); }

.bg-primary { background: var(--background-primary); }
.bg-secondary { background: var(--background-secondary); }
.bg-tertiary { background: var(--background-tertiary); }

.m-0 { margin: 0; }
.m-xs { margin: var(--spacing-xs); }
.m-sm { margin: var(--spacing-sm); }
.m-md { margin: var(--spacing-md); }
.m-lg { margin: var(--spacing-lg); }
.m-xl { margin: var(--spacing-xl); }

.mt-0 { margin-top: 0; }
.mt-xs { margin-top: var(--spacing-xs); }
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-xs { margin-bottom: var(--spacing-xs); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.p-0 { padding: 0; }
.p-xs { padding: var(--spacing-xs); }
.p-sm { padding: var(--spacing-sm); }
.p-md { padding: var(--spacing-md); }
.p-lg { padding: var(--spacing-lg); }
.p-xl { padding: var(--spacing-xl); }

.hidden { display: none; }
.block { display: block; }
.inline-block { display: inline-block; }
.flex { display: flex; }
.inline-flex { display: inline-flex; }
.grid { display: grid; }

.flex-row { flex-direction: row; }
.flex-column { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.flex-nowrap { flex-wrap: nowrap; }

.justify-start { justify-content: flex-start; }
.justify-center { justify-content: center; }
.justify-end { justify-content: flex-end; }
.justify-between { justify-content: space-between; }
.justify-around { justify-content: space-around; }

.items-start { align-items: flex-start; }
.items-center { align-items: center; }
.items-end { align-items: flex-end; }
.items-stretch { align-items: stretch; }

.gap-xs { gap: var(--spacing-xs); }
.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }
.gap-xl { gap: var(--spacing-xl); }

.rounded-sm { border-radius: var(--radius-sm); }
.rounded-md { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-xl { border-radius: var(--radius-xl); }
.rounded-full { border-radius: var(--radius-full); }

.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow-md { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }
.shadow-xl { box-shadow: var(--shadow-xl); }
.shadow-none { box-shadow: none; }

.overflow-hidden { overflow: hidden; }
.overflow-auto { overflow: auto; }
.overflow-scroll { overflow: scroll; }
.overflow-x-auto { overflow-x: auto; }
.overflow-y-auto { overflow-y: auto; }

.cursor-pointer { cursor: pointer; }
.cursor-not-allowed { cursor: not-allowed; }
.cursor-help { cursor: help; }

.select-none { user-select: none; }
.select-text { user-select: text; }
.select-all { user-select: all; }

/* Print Styles */
@media print {
.sidebar,
.menu-toggle,
.btn,
.no-print {
    display: none !important;
}


.main-content {
    margin-left: 0 !important;
    padding: 0 !important;
}

.app-container {
    box-shadow: none !important;
}

}

/* ===================================
   Day Content Beautiful Styling
   =================================== */

/* Day Header - Make it stunning */
.day-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding: 60px 40px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 24px;
    position: relative;
    overflow: hidden;
    box-shadow: 0 20px 40px rgba(102, 126, 234, 0.25);
}

.day-header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: shimmer 3s ease-in-out infinite;
}

@keyframes shimmer {
    0%, 100% { transform: rotate(0deg); }
    50% { transform: rotate(180deg); }
}

.day-title {
    color: white;
    font-size: 2.5rem;
    font-weight: 700;
    margin: 0 0 12px 0;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: relative;
    z-index: 1;
}

.day-subtitle {
    color: rgba(255, 255, 255, 0.95);
    font-size: 1.25rem;
    font-weight: 400;
    position: relative;
    z-index: 1;
}

/* Section Headers - Visual hierarchy */
.content-section {
    margin: 48px 0;
}

.section-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 24px;
    padding: 24px;
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.05), rgba(147, 51, 234, 0.05));
    border-radius: 16px;
    border-left: 4px solid #3b82f6;
}

.section-icon {
    font-size: 2rem;
    line-height: 1;
}

.section-header h3 {
    color: #1e293b;
    font-size: 1.5rem;
    margin: 0;
    font-weight: 600;
}

.section-header[data-type="morning"] {
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.08), rgba(245, 158, 11, 0.08));
    border-left-color: #fbbf24;
}

.section-header[data-type="morning"] .section-icon {
    color: #f59e0b;
}

.section-header[data-type="afternoon"] {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.08), rgba(37, 99, 235, 0.08));
    border-left-color: #3b82f6;
}

.section-header[data-type="afternoon"] .section-icon {
    color: #2563eb;
}

.section-header[data-type="evening"] {
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.08), rgba(109, 40, 217, 0.08));
    border-left-color: #8b5cf6;
}

.section-header[data-type="evening"] .section-icon {
    color: #7c3aed;
}

/* Content Boxes - Beautiful cards */
.concept-intro,
.real-world-example,
.interactive-demo,
.key-insight,
.milestone-moment,
.code-explanation {
    padding: 24px;
    border-radius: 12px;
    margin: 16px 0;
    position: relative;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.concept-intro {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.05), rgba(5, 150, 105, 0.05));
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.concept-intro:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(16, 185, 129, 0.1);
}

.real-world-example {
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.05), rgba(245, 158, 11, 0.05));
    border: 1px solid rgba(251, 191, 36, 0.2);
}

.real-world-example:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(251, 191, 36, 0.1);
}

.interactive-demo {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.05), rgba(79, 70, 229, 0.05));
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.interactive-demo:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(99, 102, 241, 0.1);
}

.key-insight {
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.05), rgba(220, 38, 38, 0.05));
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.key-insight:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(239, 68, 68, 0.1);
}

.milestone-moment {
    background: linear-gradient(135deg, rgba(147, 51, 234, 0.05), rgba(126, 34, 206, 0.05));
    border: 1px solid rgba(147, 51, 234, 0.2);
}

.milestone-moment:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(147, 51, 234, 0.1);
}

.concept-intro h4,
.real-world-example h5,
.interactive-demo h5,
.key-insight h5,
.milestone-moment h4,
.code-explanation h5 {
    margin-top: 0;
    margin-bottom: 16px;
    color: #1e293b;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Interactive demo details styling */
.interactive-demo details {
    margin-top: 16px;
    padding: 16px;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 8px;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.interactive-demo summary {
    cursor: pointer;
    font-weight: 500;
    color: #4f46e5;
    transition: color 0.2s ease;
}

.interactive-demo summary:hover {
    color: #4338ca;
}

.interactive-demo details[open] summary {
    margin-bottom: 12px;
    color: #4338ca;
}

.interactive-demo details ol {
    margin: 12px 0;
    padding-left: 24px;
}

.interactive-demo details li {
    margin: 8px 0;
    color: #475569;
}

.interactive-demo details p strong {
    color: #1e293b;
    font-weight: 600;
}

/* Comparison Grid */
.comparison-grid {
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin: 20px 0;
}

.comparison-item {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 16px;
    align-items: center;
    background: rgba(59, 130, 246, 0.02);
    border-radius: 8px;
    overflow: hidden;
}

.human-version {
    padding: 16px 20px;
    background: rgba(59, 130, 246, 0.08);
    font-weight: 500;
    color: #1e293b;
    border-right: 2px solid rgba(59, 130, 246, 0.2);
}

.computer-version {
    padding: 12px 16px;
}

.computer-version pre {
    margin: 0;
    padding: 12px;
    background: #1a1d24;
    color: #e9ecef;
    border-radius: 6px;
    font-family: var(--font-mono);
    font-size: 0.9rem;
    line-height: 1.4;
    border-left: 3px solid var(--primary-500);
}

@media (max-width: 768px) {
    .comparison-item {
        grid-template-columns: 1fr;
    }

    .human-version {
        border-right: none;
        border-bottom: 2px solid rgba(59, 130, 246, 0.2);
    }
}