/* ============================================
   WebDev Academy - Course Website
   Dark Theme Design System
   ============================================ */

/* CSS Custom Properties (Design Tokens) */
:root {
    /* Color Palette - Dark Theme with Focus Enhancement */
    --color-bg-primary: #0d1117;
    --color-bg-secondary: #161b22;
    --color-bg-tertiary: #21262d;
    --color-bg-elevated: #1c2128;
    --color-bg-overlay: rgba(13, 17, 23, 0.85);

    /* Text Colors - High Contrast for Readability */
    --color-text-primary: #e6edf3;
    --color-text-secondary: #8b949e;
    --color-text-muted: #6e7681;
    --color-text-link: #58a6ff;
    --color-text-link-hover: #79c0ff;

    /* Accent Colors - Focus Points */
    --color-accent-primary: #238636;
    --color-accent-primary-hover: #2ea043;
    --color-accent-secondary: #1f6feb;
    --color-accent-warning: #d29922;
    --color-accent-danger: #f85149;
    --color-accent-purple: #a371f7;
    --color-accent-cyan: #39c5cf;

    /* Border Colors */
    --color-border-default: #30363d;
    --color-border-muted: #21262d;
    --color-border-subtle: rgba(240, 246, 252, 0.1);

    /* Code/Math Highlighting */
    --color-code-bg: #161b22;
    --color-code-border: #30363d;
    --color-syntax-keyword: #ff7b72;
    --color-syntax-string: #a5d6ff;
    --color-syntax-number: #79c0ff;
    --color-syntax-comment: #8b949e;
    --color-syntax-function: #d2a8ff;

    /* Spacing Scale */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;

    /* Typography Scale */
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;

    /* Line Heights - Optimized for Reading */
    --line-height-tight: 1.25;
    --line-height-normal: 1.6;
    --line-height-relaxed: 1.75;

    /* Font Families */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', 'Monaco', monospace;

    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(88, 166, 255, 0.15);

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

    /* Layout */
    --content-max-width: 900px;
    --sidebar-width: 280px;
    --header-height: 64px;
}

/* ============================================
   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-sans);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-text-primary);
    background-color: var(--color-bg-primary);
    min-height: 100vh;
}

/* Focus Styles for Accessibility */
:focus-visible {
    outline: 2px solid var(--color-accent-secondary);
    outline-offset: 2px;
}

/* Selection Color */
::selection {
    background-color: rgba(88, 166, 255, 0.3);
    color: var(--color-text-primary);
}

/* ============================================
   Typography
   ============================================ */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 600;
    line-height: var(--line-height-tight);
    color: var(--color-text-primary);
    margin-bottom: var(--space-md);
}

h1 {
    font-size: var(--font-size-4xl);
    letter-spacing: -0.025em;
}

h2 {
    font-size: var(--font-size-3xl);
    letter-spacing: -0.02em;
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--color-border-default);
    margin-top: var(--space-2xl);
}

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

h4 {
    font-size: var(--font-size-xl);
    margin-top: var(--space-lg);
}

p {
    margin-bottom: var(--space-md);
    color: var(--color-text-secondary);
}

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

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

strong {
    font-weight: 600;
    color: var(--color-text-primary);
}

em {
    font-style: italic;
}

/* ============================================
   Layout Components
   ============================================ */

/* Main Container */
.container {
    max-width: var(--content-max-width);
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

/* App Layout with Sidebar */
.app-layout {
    display: grid;
    grid-template-columns: var(--sidebar-width) 1fr;
    min-height: 100vh;
}

/* Header */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    height: var(--header-height);
    background-color: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border-default);
    display: flex;
    align-items: center;
    padding: 0 var(--space-lg);
    backdrop-filter: blur(10px);
}

.header__logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text-primary);
    text-decoration: none;
}

.header__logo:hover {
    text-decoration: none;
    color: var(--color-text-link);
}

.header__nav {
    margin-left: auto;
    display: flex;
    gap: var(--space-lg);
}

.header__link {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

.header__link:hover {
    color: var(--color-text-primary);
    text-decoration: none;
}

/* Sidebar Navigation */
.sidebar {
    position: sticky;
    top: var(--header-height);
    height: calc(100vh - var(--header-height));
    background-color: var(--color-bg-secondary);
    border-right: 1px solid var(--color-border-default);
    padding: var(--space-lg);
    overflow-y: auto;
}

.sidebar__section {
    margin-bottom: var(--space-xl);
}

.sidebar__title {
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
    margin-bottom: var(--space-sm);
}

.sidebar__list {
    list-style: none;
}

.sidebar__item {
    margin-bottom: var(--space-xs);
}

.sidebar__link {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.sidebar__link:hover {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    text-decoration: none;
}

.sidebar__link--active {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-link);
    font-weight: 500;
}

.sidebar__link--completed {
    color: var(--color-accent-primary);
}

.sidebar__icon {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.sidebar__icon svg {
    width: 100%;
    height: 100%;
    stroke: currentColor;
}

/* Main Content Area */
.main-content {
    padding: var(--space-2xl) var(--space-3xl);
    max-width: 100%;
    overflow-x: hidden;
}

/* ============================================
   Course Content Components
   ============================================ */

/* Problem/Exercise Card */
.problem-card {
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    margin-bottom: var(--space-xl);
    transition: border-color var(--transition-normal);
}

.problem-card:hover {
    border-color: var(--color-border-subtle);
}

.problem-card__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-lg);
}

.problem-card__title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
    margin: 0;
}

.problem-card__badge {
    display: inline-flex;
    align-items: center;
    padding: var(--space-xs) var(--space-sm);
    font-size: var(--font-size-xs);
    font-weight: 500;
    border-radius: var(--radius-full);
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-secondary);
}

.problem-card__badge--points {
    background-color: rgba(35, 134, 54, 0.2);
    color: var(--color-accent-primary);
}

.problem-card__content {
    color: var(--color-text-secondary);
    line-height: var(--line-height-relaxed);
}

/* Solution Section */
.solution {
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-left: 3px solid var(--color-accent-primary);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    margin-top: var(--space-lg);
}

.solution__header {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
    color: var(--color-accent-primary);
    font-weight: 600;
}

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

/* Step-by-Step Explanation */
.steps {
    counter-reset: step-counter;
    list-style: none;
    margin: var(--space-lg) 0;
}

.step {
    position: relative;
    padding-left: var(--space-2xl);
    padding-bottom: var(--space-lg);
    border-left: 2px solid var(--color-border-default);
    margin-left: var(--space-md);
}

.step:last-child {
    border-left: none;
    padding-bottom: 0;
}

.step::before {
    counter-increment: step-counter;
    content: counter(step-counter);
    position: absolute;
    left: -12px;
    top: 0;
    width: 24px;
    height: 24px;
    background-color: var(--color-accent-secondary);
    color: white;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xs);
    font-weight: 600;
}

.step__title {
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--space-sm);
}

.step__content {
    color: var(--color-text-secondary);
}

/* ============================================
   Code & Math Styling
   ============================================ */

/* Inline Code */
code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background-color: var(--color-code-bg);
    border: 1px solid var(--color-code-border);
    border-radius: var(--radius-sm);
    padding: 0.15em 0.4em;
    color: var(--color-syntax-string);
}

/* Code Blocks */
pre {
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    background-color: var(--color-code-bg);
    border: 1px solid var(--color-code-border);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    overflow-x: auto;
    margin: var(--space-lg) 0;
    line-height: 1.5;
}

pre code {
    background: none;
    border: none;
    padding: 0;
    font-size: inherit;
}

/* Grammar/Production Rules */
.grammar {
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    font-family: var(--font-mono);
    margin: var(--space-lg) 0;
}

.grammar__rule {
    margin-bottom: var(--space-sm);
    display: flex;
    align-items: baseline;
    gap: var(--space-md);
}

.grammar__nonterminal {
    color: var(--color-accent-purple);
    font-weight: 600;
}

.grammar__arrow {
    color: var(--color-text-muted);
}

.grammar__terminal {
    color: var(--color-syntax-string);
}

.grammar__or {
    color: var(--color-text-muted);
    padding-left: 2.5rem;
}

/* Math/Formula Display */
.math-block {
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    margin: var(--space-lg) 0;
    text-align: center;
    font-size: var(--font-size-lg);
    overflow-x: auto;
}

.math-inline {
    font-family: var(--font-mono);
    background-color: var(--color-code-bg);
    padding: 0.1em 0.3em;
    border-radius: var(--radius-sm);
}

/* ============================================
   Tables
   ============================================ */
.table-container {
    overflow-x: auto;
    margin: var(--space-lg) 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--font-size-sm);
}

thead {
    background-color: var(--color-bg-tertiary);
}

th {
    padding: var(--space-md);
    text-align: left;
    font-weight: 600;
    color: var(--color-text-primary);
    border-bottom: 2px solid var(--color-border-default);
}

td {
    padding: var(--space-md);
    border-bottom: 1px solid var(--color-border-muted);
    color: var(--color-text-secondary);
}

tr:hover td {
    background-color: var(--color-bg-tertiary);
}

/* Transition Table (for automata) */
.transition-table {
    font-family: var(--font-mono);
}

.transition-table th,
.transition-table td {
    text-align: center;
    min-width: 60px;
}

.transition-table .state-header {
    color: var(--color-accent-purple);
}

.transition-table .final-state {
    border: 2px solid var(--color-accent-primary);
    border-radius: var(--radius-full);
}

/* ============================================
   Automata/Graph Diagrams
   ============================================ */
.diagram-container {
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    margin: var(--space-lg) 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 300px;
}

.diagram-container svg {
    max-width: 100%;
    height: auto;
}

/* ============================================
   Alert/Info Boxes
   ============================================ */
.alert {
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    margin: var(--space-lg) 0;
    display: flex;
    gap: var(--space-md);
}

.alert__icon {
    flex-shrink: 0;
    width: 20px;
    height: 20px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.alert__icon svg {
    width: 100%;
    height: 100%;
    stroke: currentColor;
}

.alert__content {
    flex: 1;
}

.alert--info {
    background-color: rgba(31, 111, 235, 0.1);
    border: 1px solid rgba(31, 111, 235, 0.3);
    color: var(--color-text-link);
}

.alert--tip {
    background-color: rgba(35, 134, 54, 0.1);
    border: 1px solid rgba(35, 134, 54, 0.3);
    color: var(--color-accent-primary);
}

.alert--warning {
    background-color: rgba(210, 153, 34, 0.1);
    border: 1px solid rgba(210, 153, 34, 0.3);
    color: var(--color-accent-warning);
}

.alert--important {
    background-color: rgba(163, 113, 247, 0.1);
    border: 1px solid rgba(163, 113, 247, 0.3);
    color: var(--color-accent-purple);
}

/* ============================================
   Progress Indicator
   ============================================ */
.progress-bar {
    height: 8px;
    background-color: var(--color-bg-tertiary);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--space-md);
}

.progress-bar__fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-accent-primary), var(--color-accent-cyan));
    border-radius: var(--radius-full);
    transition: width var(--transition-normal);
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-lg);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
}

.btn:hover {
    text-decoration: none;
}

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

.btn--primary:hover {
    background-color: var(--color-accent-primary-hover);
    border-color: var(--color-accent-primary-hover);
}

.btn--secondary {
    background-color: transparent;
    color: var(--color-text-secondary);
    border-color: var(--color-border-default);
}

.btn--secondary:hover {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text-primary);
}

.btn--outline {
    background-color: transparent;
    color: var(--color-accent-secondary);
    border-color: var(--color-accent-secondary);
}

.btn--outline:hover {
    background-color: var(--color-accent-secondary);
    color: white;
}

/* ============================================
   Collapsible Sections
   ============================================ */
.collapsible {
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-md);
}

.collapsible__trigger {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-md) var(--space-lg);
    background-color: var(--color-bg-tertiary);
    border: none;
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: 500;
    color: var(--color-text-primary);
    text-align: left;
    transition: background-color var(--transition-fast);
}

.collapsible__trigger:hover {
    background-color: var(--color-bg-elevated);
}

.collapsible__icon {
    transition: transform var(--transition-fast);
}

.collapsible--open .collapsible__icon {
    transform: rotate(180deg);
}

.collapsible__content {
    padding: var(--space-lg);
    display: none;
}

.collapsible--open .collapsible__content {
    display: block;
}

/* ============================================
   Parse Tree / Derivation Display
   ============================================ */
.derivation {
    font-family: var(--font-mono);
    margin: var(--space-lg) 0;
}

.derivation__step {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-sm) 0;
    border-bottom: 1px solid var(--color-border-muted);
}

.derivation__arrow {
    color: var(--color-text-muted);
    flex-shrink: 0;
}

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

.derivation__highlight {
    background-color: rgba(88, 166, 255, 0.2);
    border-radius: var(--radius-sm);
    padding: 0 var(--space-xs);
}

/* ============================================
   First/Follow Sets Display
   ============================================ */
.set-display {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--space-md);
    margin: var(--space-lg) 0;
}

.set-item {
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    padding: var(--space-md);
}

.set-item__label {
    font-weight: 600;
    color: var(--color-accent-purple);
    font-family: var(--font-mono);
    margin-bottom: var(--space-xs);
}

.set-item__values {
    font-family: var(--font-mono);
    color: var(--color-text-secondary);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1024px) {
    .app-layout {
        grid-template-columns: 1fr;
    }

    .sidebar {
        display: none;
    }

    .main-content {
        padding: var(--space-lg);
    }
}

@media (max-width: 768px) {
    :root {
        --font-size-base: 0.9375rem;
    }

    h1 {
        font-size: var(--font-size-2xl);
    }

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

    .problem-card {
        padding: var(--space-md);
    }

    .problem-card__header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-sm);
    }
}

/* ============================================
   Print Styles
   ============================================ */
@media print {
    body {
        background-color: white;
        color: black;
    }

    .sidebar,
    .header {
        display: none;
    }

    .main-content {
        padding: 0;
    }

    .problem-card {
        border: 1px solid #ccc;
        page-break-inside: avoid;
    }
}

/* ============================================
   Animations
   ============================================ */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-fade-in {
    animation: fadeIn var(--transition-normal) ease-out;
}

@keyframes pulse {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0.5;
    }
}

.animate-pulse {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

/* ============================================
   Icon Utility Class
   ============================================ */
.icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.25em;
    height: 1.25em;
    flex-shrink: 0;
    vertical-align: middle;
}

.icon svg {
    width: 100%;
    height: 100%;
    stroke: currentColor;
    fill: none;
}

/* ============================================
   Content Utility Classes
   ============================================ */

/* Section intro text - used for chapter introductions */
.section-intro {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-xl);
}

/* Content list with proper spacing and muted color */
.content-list {
    margin-left: var(--space-lg);
    color: var(--color-text-secondary);
}

.content-list li {
    margin-bottom: var(--space-xs);
}

/* Alert list inherits color from parent */
.alert__content ul,
.alert__content ol {
    margin: var(--space-sm) 0 0 var(--space-lg);
    color: inherit;
}

/* Consecutive alerts get automatic spacing */
.alert+.alert {
    margin-top: var(--space-md);
}

/* Status code color indicators */
.status-1xx {
    color: var(--color-accent-secondary);
}

.status-2xx {
    color: var(--color-accent-primary);
}

.status-3xx {
    color: var(--color-accent-warning);
}

.status-4xx {
    color: var(--color-accent-danger);
}

.status-5xx {
    color: var(--color-accent-purple);
}

/* Chapter footer */
.chapter-footer {
    margin-top: var(--space-3xl);
    padding-top: var(--space-xl);
    border-top: 1px solid var(--color-border-default);
    text-align: center;
}

.chapter-footer__meta {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    margin-top: var(--space-lg);
}

/* CTA button wrapper */
.cta-button {
    margin-top: var(--space-md);
    margin-bottom: 0;
}

/* ============================================
   Quiz Component
   ============================================ */
.quiz {
    margin: var(--space-lg) 0;
}

.quiz h4 {
    margin-bottom: var(--space-md);
    color: var(--color-text-primary);
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md);
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.quiz-option:hover {
    border-color: var(--color-text-link);
    background-color: var(--color-bg-elevated);
}

.option-letter {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-full);
    font-weight: 600;
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    flex-shrink: 0;
}

.quiz-option.correct {
    background-color: rgba(35, 134, 54, 0.2);
    border-color: var(--color-accent-primary);
}

.quiz-option.correct .option-letter {
    background-color: var(--color-accent-primary);
    border-color: var(--color-accent-primary);
    color: white;
}

.quiz-option.incorrect {
    background-color: rgba(248, 81, 73, 0.2);
    border-color: var(--color-accent-danger);
}

.quiz-option.incorrect .option-letter {
    background-color: var(--color-accent-danger);
    border-color: var(--color-accent-danger);
    color: white;
}

/* ============================================
   Exercise Component
   ============================================ */
.exercise {
    margin: var(--space-lg) 0;
}

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

.exercise-badge {
    display: inline-flex;
    align-items: center;
    padding: var(--space-xs) var(--space-sm);
    background: linear-gradient(135deg, var(--color-accent-purple), var(--color-accent-secondary));
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 700;
    letter-spacing: 0.05em;
    color: white;
}

.exercise textarea {
    width: 100%;
    min-height: 150px;
    padding: var(--space-md);
    background-color: var(--color-bg-tertiary);
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-family: var(--font-mono);
    font-size: var(--font-size-sm);
    resize: vertical;
    margin-bottom: var(--space-md);
}

.exercise textarea:focus {
    outline: none;
    border-color: var(--color-text-link);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
}

.exercise textarea::placeholder {
    color: var(--color-text-muted);
}

.btn-group {
    display: flex;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
}

.output-preview {
    width: 100%;
    min-height: 100px;
    padding: var(--space-lg);
    background-color: #ffffff;
    border: 1px solid var(--color-border-default);
    border-radius: var(--radius-md);
    color: #1a1a1a;
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
}

.output-preview em {
    color: #666666;
}

/* Feedback styling for hints */
.feedback {
    padding: var(--space-md);
    background-color: rgba(210, 153, 34, 0.15);
    border: 1px solid rgba(210, 153, 34, 0.3);
    border-radius: var(--radius-md);
    color: var(--color-accent-warning);
    margin-bottom: var(--space-md);
}