/* 顾老师英语 - 主样式表 */
:root {
    --primary: #4A90D9;
    --primary-dark: #357ABD;
    --secondary: #F5A623;
    --bg: #f0f4f8;
    --text: #2c3e50;
    --text-light: #7f8c8d;
    --white: #ffffff;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --radius: 12px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
}

a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }

/* Header */
.site-header {
    background: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.main-nav ul {
    display: flex;
    list-style: none;
    gap: 24px;
}

.main-nav a {
    color: var(--text);
    font-weight: 500;
    padding: 8px 0;
    border-bottom: 2px solid transparent;
    transition: all 0.3s;
}

.main-nav a:hover,
.main-nav a.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 10px 24px;
    border-radius: var(--radius);
    font-weight: 600;
    cursor: pointer;
    border: 2px solid transparent;
    transition: all 0.3s;
    font-size: 0.95rem;
}

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

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

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

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

.btn-sm {
    padding: 6px 16px;
    font-size: 0.85rem;
}

/* Hero */
.hero {
    background: linear-gradient(135deg, var(--primary), #6C5CE7);
    color: var(--white);
    text-align: center;
    padding: 80px 20px;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 16px;
}

.hero p {
    font-size: 1.2rem;
    margin-bottom: 32px;
    opacity: 0.9;
}

/* Features */
.features {
    max-width: 1200px;
    margin: 0 auto;
    padding: 60px 20px;
}

.features h2 {
    text-align: center;
    margin-bottom: 40px;
    font-size: 2rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.feature-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-4px);
}

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.feature-card h3 {
    margin-bottom: 12px;
    color: var(--primary);
}

.feature-card p {
    color: var(--text-light);
    margin-bottom: 20px;
}

/* Daily Preview */
.daily-preview {
    max-width: 1200px;
    margin: 0 auto;
    padding: 60px 20px;
    text-align: center;
}

.daily-preview h2 {
    margin-bottom: 32px;
    font-size: 2rem;
}

.word-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 32px;
}

/* Flashcard */
.flashcard {
    perspective: 1000px;
    height: 200px;
    cursor: pointer;
}

.card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

.flashcard.flipped .card-inner {
    transform: rotateY(180deg);
}

.card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--radius);
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow);
}

.card-front {
    background: var(--white);
}

.card-front h3 {
    font-size: 1.5rem;
    color: var(--primary);
    margin-bottom: 8px;
}

.phonetic {
    color: var(--text-light);
    font-style: italic;
}

.card-back {
    background: var(--primary);
    color: var(--white);
    transform: rotateY(180deg);
}

.card-back .meaning {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.card-back .example {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* Footer */
.site-footer {
    background: var(--text);
    color: var(--white);
    padding: 40px 20px 20px;
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 32px;
    margin-bottom: 32px;
}

.footer-col h4 {
    margin-bottom: 16px;
    color: var(--secondary);
}

.footer-col ul {
    list-style: none;
}

.footer-col a {
    color: #ccc;
    line-height: 2;
}

.footer-col a:hover {
    color: var(--white);
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: #999;
}

/* Admin */
.admin-panel {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
}

.admin-panel h1 {
    margin-bottom: 32px;
    color: var(--primary);
}

.admin-section {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    margin-bottom: 32px;
}

.admin-section h2 {
    margin-bottom: 24px;
}

.admin-form .form-group {
    margin-bottom: 16px;
}

.admin-form label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
}

.admin-form input,
.admin-form textarea {
    width: 100%;
    padding: 10px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.admin-form input:focus,
.admin-form textarea:focus {
    border-color: var(--primary);
    outline: none;
}

.admin-form textarea {
    height: 100px;
    resize: vertical;
}

.admin-table {
    width: 100%;
    border-collapse: collapse;
}

.admin-table th,
.admin-table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid #eee;
}

.admin-table th {
    background: var(--bg);
    font-weight: 600;
}

.alert {
    padding: 12px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.alert-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

/* Page styles */
.page-daily,
.page-grammar,
.page-speaking {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
}

.page-daily h1,
.page-grammar h1,
.page-speaking h1 {
    text-align: center;
    color: var(--primary);
    margin-bottom: 12px;
}

.page-desc {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 40px;
}

.word-cards.full {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.grammar-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    margin-bottom: 24px;
}

.grammar-card h2 {
    color: var(--primary);
    margin-bottom: 16px;
}

.grammar-content {
    margin-bottom: 20px;
    line-height: 1.8;
}

.examples h3 {
    margin-bottom: 16px;
    color: var(--secondary);
}

.example-item {
    background: var(--bg);
    padding: 16px;
    border-radius: 8px;
    margin-bottom: 12px;
}

.example-item .question {
    font-weight: 600;
    margin-bottom: 8px;
}

.example-item .answer {
    color: var(--primary);
    margin-bottom: 4px;
}

.example-item .explanation {
    color: var(--text-light);
    font-size: 0.9rem;
}

.topic-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    margin-bottom: 24px;
}

.topic-card h2 {
    color: var(--primary);
    margin-bottom: 8px;
}

.topic-card p {
    color: var(--text-light);
    margin-bottom: 16px;
}

.audio-controls {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}

.audio-controls audio {
    flex: 1;
    min-width: 200px;
}

.score-display {
    margin-top: 12px;
    font-size: 1.1rem;
}

.score-value {
    color: var(--secondary);
    font-weight: 700;
}

.pagination {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-top: 40px;
}

/* Responsive */
@media (max-width: 768px) {
    .header-inner {
        flex-wrap: wrap;
        height: auto;
        padding: 12px 20px;
    }
    
    .main-nav ul {
        gap: 12px;
        flex-wrap: wrap;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
}