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

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --background-color: #ecf0f1;
    --accent-color: #e74c3c;
    --success-color: #2ecc71;
    --text-color: #2c3e50;
    --light-text: #7f8c8d;
    --border-radius: 12px;
    --shadow: 0 4px 20px rgba(44, 62, 80, 0.1);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    padding-bottom: 80px;
    background-image: 
        radial-gradient(circle at 1px 1px, rgba(44, 62, 80, 0.1) 1px, transparent 0);
    background-size: 20px 20px;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        linear-gradient(90deg, transparent 79px, rgba(44, 62, 80, 0.04) 81px, transparent 82px),
        linear-gradient(rgba(44, 62, 80, 0.02) 0.5px, transparent 0.5px);
    background-size: 82px 20px, 100% 20px;
    pointer-events: none;
    z-index: -1;
}

header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 2rem 1rem;
    text-align: center;
    box-shadow: var(--shadow);
}

header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

header p {
    opacity: 0.9;
    font-size: 1.1rem;
}

main {
    padding: 1rem;
    max-width: 1200px;
    margin: 0 auto;
}

.content-section {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

.content-section.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.pairing-generator {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
}

.pairing-generator h2 {
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    font-size: 1.5rem;
}

.controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

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

.control-group label {
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

select, input {
    padding: 0.75rem;
    border: 2px solid #ddd;
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    background: white;
}

select:focus, input:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.primary-btn, .secondary-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
}

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

.primary-btn:hover {
    background: #2980b9;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(52, 152, 219, 0.3);
}

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

.secondary-btn:hover {
    background: #27ae60;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(46, 204, 113, 0.3);
}

.pairing-display {
    background: #f8f9fa;
    border-radius: var(--border-radius);
    padding: 2rem;
    border: 2px dashed #ddd;
}

.font-pair {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 1.5rem;
}

.font-info h3, .font-info h4 {
    margin-bottom: 0.5rem;
    font-size: 1.8rem;
}

.font-info h4 {
    font-size: 1.2rem;
}

.font-name {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

.preview-container {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.preview-container h2 {
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    font-size: 1.5rem;
}

.preview-controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.preview-area {
    background: #fff;
    border: 2px solid #eee;
    border-radius: var(--border-radius);
    padding: 2rem;
    min-height: 400px;
}

.preview-content h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.preview-content h2 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    color: var(--light-text);
    line-height: 1.3;
}

.preview-content p {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.preview-content blockquote {
    font-size: 1.3rem;
    font-style: italic;
    border-left: 4px solid var(--secondary-color);
    padding-left: 1.5rem;
    margin: 1.5rem 0;
    color: var(--primary-color);
}

.saved-pairings {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}

.saved-pairing {
    background: white;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    position: relative;
    transition: var(--transition);
}

.saved-pairing:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(44, 62, 80, 0.15);
}

.saved-pairing h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.saved-pairing .font-pair {
    margin-bottom: 1rem;
}

.saved-pairing .actions {
    display: flex;
    gap: 0.5rem;
}

.delete-btn {
    background: var(--accent-color);
    color: white;
    border: none;
    padding: 0.5rem;
    border-radius: 50%;
    cursor: pointer;
    transition: var(--transition);
    position: absolute;
    top: 1rem;
    right: 1rem;
}

.delete-btn:hover {
    background: #c0392b;
    transform: scale(1.1);
}

.education-content {
    display: grid;
    gap: 2rem;
}

.principle {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.principle h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
    font-size: 1.3rem;
}

.principle p {
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.example {
    background: #f8f9fa;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.hierarchy-example * {
    font-family: 'Georgia', serif;
}

.personality-example {
    display: grid;
    gap: 1rem;
}

.personality-example span {
    font-size: 1.2rem;
    padding: 0.5rem;
    text-align: center;
    background: white;
    border-radius: 8px;
}

.faq-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.faq-item {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 1.5rem;
    background: none;
    border: none;
    text-align: left;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary-color);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.faq-question:hover {
    background: #f8f9fa;
}

.faq-icon {
    font-size: 1.5rem;
    transition: var(--transition);
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--light-text);
    line-height: 1.7;
    transition: var(--transition);
}

.faq-answer[hidden] {
    display: none;
}

.empty-state {
    text-align: center;
    color: var(--light-text);
    font-style: italic;
    padding: 3rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: white;
    display: flex;
    justify-content: space-around;
    padding: 0.75rem 0;
    box-shadow: 0 -2px 20px rgba(44, 62, 80, 0.1);
    z-index: 1000;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--light-text);
    transition: var(--transition);
    padding: 0.5rem;
    border-radius: var(--border-radius);
    min-width: 60px;
}

.nav-item.active {
    color: var(--secondary-color);
    background: rgba(52, 152, 219, 0.1);
}

.nav-item i {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
}

.nav-item span {
    font-size: 0.8rem;
    font-weight: 500;
}

footer {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--light-text);
    font-size: 0.9rem;
    margin-top: 3rem;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 1.5rem;
    }
    
    header p {
        font-size: 1rem;
    }
    
    .font-pair {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .preview-content h1 {
        font-size: 2rem;
    }
    
    .preview-content h2 {
        font-size: 1.5rem;
    }
    
    .controls {
        grid-template-columns: 1fr;
    }
    
    .preview-controls {
        grid-template-columns: 1fr;
    }
    
    .saved-pairings {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    main {
        padding: 0.5rem;
    }
    
    .pairing-generator, .preview-container, .principle {
        padding: 1rem;
    }
    
    .preview-area {
        padding: 1rem;
    }
    
    .preview-content h1 {
        font-size: 1.8rem;
    }
    
    .nav-item span {
        font-size: 0.7rem;
    }
    
    .nav-item i {
        font-size: 1.3rem;
    }
}

.loading {
    opacity: 0.6;
    pointer-events: none;
}

.fade-in {
    animation: fadeIn 0.5s ease-in-out;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.pulse {
    animation: pulse 1.5s infinite;
}