:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --background-color: #ecf0f1;
    --accent-color: #e74c3c;
    --success-color: #2ecc71;
    --text-color: #2c3e50;
    --border-color: #bdc3c7;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --paper-texture: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100"><defs><pattern id="paper" patternUnits="userSpaceOnUse" width="100" height="100"><rect width="100" height="100" fill="%23ecf0f1"/><circle cx="20" cy="20" r="1" fill="%23d5dbdb" opacity="0.3"/><circle cx="80" cy="40" r="0.5" fill="%23d5dbdb" opacity="0.2"/><circle cx="40" cy="80" r="1.5" fill="%23d5dbdb" opacity="0.1"/></pattern></defs><rect width="100" height="100" fill="url(%23paper)"/></svg>');
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--background-color);
    background-image: var(--paper-texture);
    color: var(--text-color);
    line-height: 1.6;
    padding-bottom: 80px;
}

.app-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 1.5rem;
    text-align: center;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.app-header h1 {
    font-size: 1.8rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

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

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

.section {
    display: none;
    background: white;
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.section.active {
    display: block;
}

.section h2 {
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    font-size: 1.5rem;
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 0.5rem;
}

.input-group {
    margin-bottom: 1rem;
}

.input-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--primary-color);
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

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

.input-group input[type="color"] {
    height: 50px;
    cursor: pointer;
}

.btn-primary,
.btn-secondary {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--secondary-color), #2980b9);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
}

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

.btn-secondary:hover {
    background: #27ae60;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(46, 204, 113, 0.3);
}

.color-picker-container {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

.palette-display {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    margin: 1.5rem 0;
    border: 1px solid var(--border-color);
}

.color-swatches {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(80px, 1fr));
    gap: 1rem;
    margin: 1rem 0;
}

.color-swatch {
    aspect-ratio: 1;
    border-radius: 8px;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: transform 0.3s ease;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.5);
}

.color-swatch:hover {
    transform: scale(1.05);
}

.color-swatch .color-code {
    position: absolute;
    bottom: 5px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.7rem;
    background: rgba(0,0,0,0.7);
    padding: 2px 4px;
    border-radius: 3px;
}

.palette-actions {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

#colorWheel {
    display: block;
    margin: 1.5rem auto;
    border-radius: 50%;
    box-shadow: var(--shadow);
    max-width: 100%;
    height: auto;
}

.contrast-tester {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

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

.contrast-results {
    margin-top: 1.5rem;
    padding: 1rem;
    background: white;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.preview {
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
    text-align: center;
    font-size: 1.1rem;
    font-weight: 500;
}

.results-data {
    display: grid;
    gap: 0.5rem;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem;
    background: #f8f9fa;
    border-radius: 6px;
}

.result-status {
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: bold;
}

.result-status.pass {
    background: var(--success-color);
    color: white;
}

.result-status.fail {
    background: var(--accent-color);
    color: white;
}

.simulation-controls {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

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

.original-colors,
.simulated-colors {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.original-colors h3,
.simulated-colors h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.saved-palettes {
    display: grid;
    gap: 1rem;
}

.saved-palette {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.saved-palette h4 {
    margin-bottom: 1rem;
    color: var(--primary-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.palette-meta {
    font-size: 0.8rem;
    color: #7f8c8d;
}

.delete-palette {
    background: var(--accent-color);
    color: white;
    border: none;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
}

.delete-palette:hover {
    background: #c0392b;
}

.empty-state {
    text-align: center;
    color: #7f8c8d;
    font-style: italic;
    padding: 2rem;
}

.faq-container {
    display: grid;
    gap: 1rem;
}

.faq-item {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 1rem;
    background: #f8f9fa;
    border: none;
    text-align: left;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: var(--primary-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.3s ease;
}

.faq-question:hover {
    background: #e9ecef;
}

.faq-question[aria-expanded="true"] {
    background: var(--secondary-color);
    color: white;
}

.faq-icon {
    font-size: 1.2rem;
    font-weight: bold;
    transition: transform 0.3s ease;
}

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

.faq-answer {
    padding: 1rem;
    background: white;
    border-top: 1px solid var(--border-color);
    animation: fadeIn 0.3s ease;
}

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

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

.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: white;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    padding: 0.5rem 0;
    box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
    z-index: 1000;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: #7f8c8d;
    transition: color 0.3s ease;
    padding: 0.5rem;
    border-radius: 8px;
    min-width: 60px;
}

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

.nav-item i {
    font-size: 1.2rem;
    margin-bottom: 0.25rem;
}

.nav-item span {
    font-size: 0.7rem;
    font-weight: 500;
}

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

@media (max-width: 768px) {
    .app-main {
        padding: 0.5rem;
    }
    
    .section {
        padding: 1rem;
        margin-bottom: 0.5rem;
    }
    
    .color-inputs {
        grid-template-columns: 1fr;
    }
    
    .simulation-display {
        grid-template-columns: 1fr;
    }
    
    .palette-actions {
        flex-direction: column;
    }
    
    .color-swatches {
        grid-template-columns: repeat(auto-fit, minmax(60px, 1fr));
        gap: 0.5rem;
    }
    
    #colorWheel {
        width: 250px;
        height: 250px;
    }
}

@media (max-width: 480px) {
    .app-header h1 {
        font-size: 1.5rem;
    }
    
    .nav-item span {
        font-size: 0.6rem;
    }
    
    .nav-item i {
        font-size: 1rem;
    }
}