* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --success-color: #27ae60;
    --danger-color: #e74c3c;
    --background: #ecf0f1;
    --card-background: #ffffff;
    --text-color: #2c3e50;
    --border-color: #bdc3c7;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 1.5rem;
    text-align: center;
    box-shadow: var(--shadow);
}

header h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

main {
    flex: 1;
    padding: 1rem;
}

/* Upload Section */
.upload-section {
    margin-bottom: 2rem;
}

.upload-area {
    background: var(--card-background);
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    transition: all 0.3s ease;
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: #f8f9fa;
}

.upload-label {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    cursor: pointer;
    color: var(--primary-color);
}

.upload-label svg {
    opacity: 0.7;
}

.upload-label span {
    font-size: 1rem;
    font-weight: 500;
}

.file-info {
    margin-top: 1rem;
    padding: 0.75rem;
    background: var(--card-background);
    border-radius: 8px;
    font-size: 0.9rem;
    color: var(--success-color);
    display: none;
}

.file-info.show {
    display: block;
}

/* Book Section */
.book-section {
    background: var(--card-background);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.book-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--secondary-color);
}

.book-content {
    max-height: 200px;
    overflow-y: auto;
    padding: 1rem;
    background: #f8f9fa;
    border-radius: 8px;
    font-size: 0.95rem;
    line-height: 1.8;
    margin-bottom: 1rem;
}

.progress-info {
    text-align: center;
    font-weight: 500;
    color: var(--primary-color);
}

/* Controls Section */
.controls-section {
    background: var(--card-background);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.main-controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.btn-primary,
.btn-secondary {
    flex: 1;
    padding: 1rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    -webkit-tap-highlight-color: transparent;
}

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

.btn-primary:hover:not(:disabled) {
    background: #2980b9;
    transform: translateY(-2px);
}

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

.btn-secondary:hover:not(:disabled) {
    background: #95a5a6;
    transform: translateY(-2px);
}

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

.btn-primary:active:not(:disabled),
.btn-secondary:active:not(:disabled) {
    transform: scale(0.98);
}

/* Advanced Controls */
.advanced-controls {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    margin-bottom: 1.5rem;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.control-group label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
}

.control-group label span {
    margin-left: auto;
    color: var(--primary-color);
    font-weight: 600;
}

input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--border-color);
    outline: none;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    border: none;
}

.voice-select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background: white;
    font-size: 0.9rem;
    cursor: pointer;
}

/* Progress Bar */
.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 1.5rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--success-color));
    width: 0%;
    transition: width 0.3s ease;
}

/* Action Buttons */
.action-buttons {
    display: flex;
    gap: 0.75rem;
}

.action-buttons button {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--primary-color);
    border-radius: 8px;
    background: white;
    color: var(--primary-color);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.action-buttons button:hover {
    background: var(--primary-color);
    color: white;
}

/* Instructions */
.instructions {
    background: var(--card-background);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.instructions h2 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--secondary-color);
}

.instructions ol {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.instructions li {
    margin-bottom: 0.5rem;
}

.tip {
    padding: 1rem;
    background: #fff3cd;
    border-left: 4px solid #ffc107;
    border-radius: 4px;
    margin-top: 1rem;
    font-size: 0.9rem;
}

/* Footer */
footer {
    background: var(--secondary-color);
    color: white;
    text-align: center;
    padding: 1rem;
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 600px) {
    header h1 {
        font-size: 1.25rem;
    }

    main {
        padding: 0.75rem;
    }

    .upload-area {
        padding: 1.5rem;
    }

    .book-section,
    .controls-section,
    .instructions {
        padding: 1rem;
    }

    .main-controls {
        flex-direction: column;
    }

    .btn-primary,
    .btn-secondary {
        padding: 0.875rem;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --background: #1a1a1a;
        --card-background: #2d2d2d;
        --text-color: #e0e0e0;
        --border-color: #444444;
    }

    .book-content {
        background: #242424;
    }

    .upload-area:hover {
        background: #3a3a3a;
    }
}

/* Loading Animation */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.loading {
    animation: pulse 1.5s ease-in-out infinite;
}