/* Modern CSS Reset */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 
     * Color Palette - Indigo-based monochromatic with semantic accents
     * Primary: Indigo (#5B5BD6) - main interactive elements
     * All colors derived from consistent hue relationships
     */
    
    /* Neutral Scale (Slate) */
    --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;
    
    /* Primary Scale (Indigo) */
    --primary-50: #eef2ff;
    --primary-100: #e0e7ff;
    --primary-200: #c7d2fe;
    --primary-300: #a5b4fc;
    --primary-400: #818cf8;
    --primary-500: #6366f1;
    --primary-600: #5B5BD6;
    --primary-700: #4338ca;
    --primary-800: #3730a3;
    --primary-900: #312e81;
    
    /* Semantic: Success (Teal - analogous to indigo) */
    --success-50: #f0fdfa;
    --success-100: #ccfbf1;
    --success-500: #14b8a6;
    --success-600: #0d9488;
    --success-700: #0f766e;
    
    /* Semantic: Error (Rose - complementary warmth) */
    --error-50: #fff1f2;
    --error-100: #ffe4e6;
    --error-500: #f43f5e;
    --error-600: #e11d48;
    --error-700: #be123c;
    
    /* Semantic: Warning (Amber - warm accent) */
    --warning-50: #fffbeb;
    --warning-100: #fef3c7;
    --warning-500: #f59e0b;
    --warning-600: #d97706;
    
    /* Applied Colors */
    --bg-primary: var(--neutral-50);
    --bg-secondary: #ffffff;
    --bg-tertiary: var(--neutral-100);
    --bg-elevated: #ffffff;
    
    --text-primary: var(--neutral-900);
    --text-secondary: var(--neutral-600);
    --text-muted: var(--neutral-400);
    --text-inverse: #ffffff;
    
    --border: var(--neutral-200);
    --border-focus: var(--primary-500);
    
    --interactive: var(--primary-600);
    --interactive-hover: var(--primary-700);
    --interactive-light: var(--primary-50);
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04);
    --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.08), 0 2px 4px -1px rgba(15, 23, 42, 0.04);
    --shadow-lg: 0 10px 15px -3px rgba(15, 23, 42, 0.08), 0 4px 6px -2px rgba(15, 23, 42, 0.04);
    
    /* Radii */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    
    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Layout */
.container {
    max-width: 720px;
    margin: 0 auto;
    padding: 40px 24px;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 48px;
}

header h1 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.02em;
    margin-bottom: 8px;
}

.subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 400;
}

/* Main game area */
main {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.game-area {
    padding: 32px;
}

/* Audio section */
.audio-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 32px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    margin-bottom: 24px;
}

.api-status {
    width: 100%;
    padding: 12px 16px;
    margin-bottom: 16px;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    text-align: center;
    background: var(--primary-50);
    color: var(--primary-700);
    border: 1px solid var(--primary-200);
}

.api-status.error {
    background: var(--error-50);
    color: var(--error-700);
    border-color: var(--error-100);
}

.audio-info {
    margin-top: 16px;
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
}

/* Input section */
.input-section {
    margin-bottom: 24px;
}

.input-section label {
    display: block;
    margin-bottom: 8px;
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

textarea {
    width: 100%;
    padding: 16px;
    font-size: 1rem;
    font-family: var(--font-sans);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-primary);
    resize: none;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
    line-height: 1.6;
}

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

textarea:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px var(--primary-100);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    font-size: 0.9375rem;
    font-weight: 600;
    font-family: var(--font-sans);
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.15s ease;
    text-decoration: none;
}

.btn:focus {
    outline: none;
    box-shadow: 0 0 0 3px var(--primary-200);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: var(--interactive);
    color: var(--text-inverse);
}

.btn-primary:hover:not(:disabled) {
    background: var(--interactive-hover);
}

.btn-success {
    background: var(--success-600);
    color: var(--text-inverse);
    width: 100%;
    margin-top: 16px;
}

.btn-success:hover:not(:disabled) {
    background: var(--success-700);
}

.icon {
    font-size: 1rem;
}

/* Hidden */
.hidden {
    display: none !important;
}

/* Results */
.results {
    animation: slideUp 0.3s ease;
}

.result-header {
    text-align: center;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 24px;
}

.result-header h2 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.score-display {
    font-size: 3.5rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    line-height: 1;
}

.pass {
    color: var(--success-600);
}

.fail {
    color: var(--error-600);
}

/* Metrics */
.metrics {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-bottom: 24px;
}

.metric-item {
    background: var(--bg-tertiary);
    padding: 16px;
    border-radius: var(--radius-sm);
    text-align: center;
}

.metric-label {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 4px;
}

.metric-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-600);
}

/* Diff legend */
.diff-legend {
    display: flex;
    justify-content: center;
    gap: 16px;
    padding: 12px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.legend-item {
    font-size: 0.75rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 4px;
}

/* Word diff styles */
.diff-correct {
    color: var(--success-700);
    background: var(--success-100);
    padding: 2px 6px;
    border-radius: 3px;
    font-weight: 500;
}

.diff-missing {
    color: var(--warning-600);
    background: var(--warning-100);
    padding: 2px 6px;
    border-radius: 3px;
    font-weight: 500;
}

.diff-wrong {
    color: var(--error-700);
    background: var(--error-100);
    padding: 2px 6px;
    border-radius: 3px;
    text-decoration: line-through;
    font-weight: 500;
}

/* Comparison */
.comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-bottom: 24px;
}

.comparison-box {
    background: var(--bg-tertiary);
    padding: 16px;
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--primary-400);
}

.comparison-box:first-child {
    border-left-color: var(--success-500);
}

.comparison-box:last-child {
    border-left-color: var(--primary-400);
}

.comparison-box h3 {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
}

.comparison-box p {
    color: var(--text-primary);
    font-size: 0.9375rem;
    line-height: 1.7;
}

#nextBtn {
    display: block;
    width: 100%;
}

/* Final results */
.final-results {
    text-align: center;
    padding: 48px 32px;
    animation: slideUp 0.3s ease;
}

.final-results h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 32px;
}

.final-score {
    margin: 32px 0;
}

.final-score-number {
    font-size: 5rem;
    font-weight: 800;
    color: var(--primary-600);
    letter-spacing: -0.04em;
    line-height: 1;
}

.final-score-label {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-top: 8px;
}

.final-verdict {
    font-size: 1rem;
    font-weight: 600;
    padding: 16px 24px;
    border-radius: var(--radius-sm);
    margin: 24px 0 32px;
    display: inline-block;
}

.final-verdict.pass {
    background: var(--success-100);
    color: var(--success-700);
}

.final-verdict.fail {
    background: var(--error-100);
    color: var(--error-700);
}

#restartBtn {
    width: auto;
    padding: 14px 32px;
}

/* Footer */
footer {
    text-align: center;
    padding: 24px;
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Animations */
@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive */
@media (max-width: 640px) {
    .container {
        padding: 24px 16px;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .game-area {
        padding: 24px 20px;
    }

    .metrics {
        grid-template-columns: 1fr;
        gap: 8px;
    }

    .metric-item {
        display: flex;
        justify-content: space-between;
        align-items: center;
        text-align: left;
    }

    .metric-label {
        margin-bottom: 0;
    }

    .comparison {
        grid-template-columns: 1fr;
    }

    .diff-legend {
        flex-direction: column;
        align-items: center;
        gap: 8px;
    }

    .final-score-number {
        font-size: 4rem;
    }
}