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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
}

/* 欢迎页面 */
.welcome-container {
    background: white;
    border-radius: 20px;
    padding: 60px 40px;
    text-align: center;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    max-width: 500px;
    margin: 100px auto;
}

.logo-container {
    margin-bottom: 40px;
}

.logo {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    box-shadow: 0 10px 30px rgba(102, 126, 234, 0.4);
}

.logo-text {
    color: white;
    font-size: 32px;
    font-weight: 700;
}

.app-name {
    font-size: 36px;
    color: #333;
    margin-bottom: 10px;
}

.app-desc {
    color: #666;
    font-size: 16px;
}

.action-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
}

/* 按钮 */
.btn {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #f0f0f0;
    color: #333;
}

.btn-secondary:hover {
    background: #e0e0e0;
}

.btn-full {
    width: 100%;
}

.btn-sm {
    padding: 8px 16px;
    font-size: 14px;
}

/* 认证页面 */
.auth-container {
    background: white;
    border-radius: 20px;
    padding: 40px;
    max-width: 450px;
    margin: 80px auto;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}

.auth-header {
    text-align: center;
    margin-bottom: 30px;
}

.auth-header h1 {
    color: #333;
    font-size: 28px;
    margin: 20px 0 10px;
}

.auth-header p {
    color: #666;
    font-size: 14px;
}

.auth-form {
    margin-bottom: 20px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: 600;
    font-size: 14px;
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 14px;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: #667eea;
}

.auth-footer {
    text-align: center;
    color: #666;
    font-size: 14px;
}

.auth-footer a {
    color: #667eea;
    text-decoration: none;
}

.auth-footer a:hover {
    text-decoration: underline;
}

/* 提示框 */
.alert {
    padding: 12px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border: 1px solid #10b981;
}

.alert-error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #ef4444;
}

/* 头部 */
.header {
    background: white;
    border-radius: 15px;
    padding: 25px 30px;
    margin-bottom: 25px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header h1 {
    color: #667eea;
    font-size: 28px;
    margin-bottom: 5px;
}

.breadcrumb {
    color: #999;
    font-size: 14px;
}

.breadcrumb a {
    color: #667eea;
    text-decoration: none;
}

.header-actions {
    display: flex;
    gap: 15px;
    align-items: center;
}

.welcome {
    color: #666;
    font-size: 14px;
}

/* 单元网格 */
.units-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
}

.unit-card {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    transition: all 0.3s;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.unit-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
}

.unit-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.unit-name {
    font-size: 22px;
    font-weight: 700;
    color: #333;
    margin-bottom: 10px;
}

.unit-description {
    color: #666;
    font-size: 14px;
    margin-bottom: 15px;
    min-height: 40px;
}

.unit-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 15px;
    border-top: 1px solid #eee;
}

.word-count {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #667eea;
    font-weight: 600;
}

.unit-actions {
    display: flex;
    gap: 10px;
}

/* 图标按钮 */
.icon-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: none;
    background: #f0f0f0;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s;
    font-size: 18px;
}

.icon-btn:hover {
    background: #667eea;
    color: white;
    transform: scale(1.1);
}

/* 空状态 */
.empty-state {
    background: white;
    border-radius: 15px;
    padding: 60px;
    text-align: center;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.empty-icon {
    font-size: 80px;
    margin-bottom: 20px;
}

.empty-text {
    font-size: 24px;
    color: #666;
    margin-bottom: 10px;
}

.empty-desc {
    color: #999;
    margin-bottom: 30px;
}

/* 单词表格 */
.words-table {
    width: 100%;
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.words-table thead {
    background: #f8f9fa;
}

.words-table th {
    padding: 15px;
    text-align: left;
    font-weight: 600;
    color: #333;
}

.words-table td {
    padding: 15px;
    border-top: 1px solid #f0f0f0;
}

.words-table tr:hover {
    background: #f8f9fa;
}

.thumbnail {
    width: 60px;
    height: 60px;
    object-fit: cover;
    border-radius: 8px;
    cursor: pointer;
}

.default-image {
    width: 60px;
    height: 60px;
    background: #f0f0f0;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
}

.play-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: none;
    background: #667eea;
    color: white;
    cursor: pointer;
    font-size: 14px;
}

.play-btn:hover {
    background: #5568d3;
}

.no-audio {
    color: #999;
    font-style: italic;
}

.action-buttons {
    display: flex;
    gap: 8px;
}

/* 模态框 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.7);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: white;
    border-radius: 15px;
    padding: 30px;
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
}

.modal-large {
    max-width: 800px;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.modal-header h2 {
    color: #333;
    font-size: 24px;
}

.close-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: none;
    background: #f0f0f0;
    cursor: pointer;
    font-size: 20px;
}

.close-btn:hover {
    background: #e0e0e0;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.upload-area {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.preview-image {
    max-width: 200px;
    max-height: 200px;
    border-radius: 8px;
    margin-top: 10px;
}

/* 图库 */
.gallery-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 15px;
    margin-bottom: 20px;
}

.gallery-item {
    position: relative;
    cursor: pointer;
    border-radius: 8px;
    overflow: hidden;
    transition: transform 0.3s;
    border: 3px solid transparent;
}

.gallery-item:hover {
    transform: scale(1.05);
    border-color: #667eea;
}

.gallery-item img {
    width: 100%;
    height: 150px;
    object-fit: cover;
}

.loading {
    text-align: center;
    padding: 40px;
    color: #999;
}

@media (max-width: 768px) {
    .units-grid {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .header {
        flex-direction: column;
        gap: 15px;
    }
    
    .header-actions {
        width: 100%;
        justify-content: center;
    }
}