/* 整体背景: 深色渐变 */
body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-image: linear-gradient(to bottom, #156778, #0f5c73, #0f526c, #134765, #183d5c, #213451, #252a45, #262239, #241a29, #1d131c, #140a0f, #000000);
    color: #ffffff;
    min-height: 100vh;
    text-rendering: optimizeLegibility;
    -webkit-font-smoothing: antialiased;
    opacity: 1;
    transition: opacity 0.7s;
    padding-left: 24px;
    padding-right: 24px;
}

#main-content {
    max-width: 1100px;
    margin: 0 auto;
    padding: 32px 0 48px 0;
}

/* 页眉样式 */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    will-change: transform;
}
.header .logo {
    font-size: 24px;
    font-weight: bold;
}
.header .contact a {
    color: #fff;
    font-weight: 600;
    font-size: 1.08rem;
    padding: 8px 18px 8px 14px;
    border-radius: 20px;
    background: linear-gradient(90deg, #4CAF50 0%, #2196F3 100%);
    box-shadow: 0 2px 8px rgba(33,150,243,0.08);
    text-decoration: none;
    margin-left: 18px;
    display: inline-flex;
    align-items: center;
    transition: background 0.2s, box-shadow 0.2s, color 0.2s;
}
.header .contact a:hover {
    background: linear-gradient(90deg, #2196F3 0%, #4CAF50 100%);
    color: #fff;
    box-shadow: 0 4px 16px rgba(33,150,243,0.18);
    text-decoration: none;
}
.header .contact a .contact-icon {
    margin-right: 6px;
    font-size: 1.1em;
    vertical-align: middle;
}

/* 搜索栏样式 */
.search-bar {
    text-align: center;
    margin: 20px 0;
    contain: content;
}
.search-engines button {
    margin: 0 5px;
    padding: 8px 12px;
    border: none;
    border-radius: 5px;
    background-color: #213451;
    color: #fff;
    cursor: pointer;
    transition: background-color 0.2s ease, color 0.2s ease;
}
.search-engines button.active {
    background-color: #4CAF50;
    color: white;
}
#searchForm {
    margin-top: 10px;
    contain: layout style;
}
#searchInput {
    width: 60%;
    padding: 8px;
    border: none;
    border-radius: 5px;
    background-color: #213451;
    color: #fff;
    transition: background-color 0.2s ease;
}
#searchInput:focus {
    background-color: #262239;
    outline: none;
}
#searchBtn {
    padding: 8px 16px;
    margin-left: 10px;
    border: none;
    border-radius: 5px;
    background-color: #4CAF50;
    color: white;
    cursor: pointer;
    transition: background-color 0.2s ease;
}
#searchBtn:hover {
    background-color: #45a049;
}

/* 书签卡片样式 */
.cards {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    padding: 0;
    contain: content;
}
.card {
    flex: 0 1 22%;
    margin: 10px;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    will-change: transform;
}
.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.3);
}
.card a {
    display: flex;
    align-items: center;
    padding: 10px;
    text-decoration: none;
    color: #ffffff;
}
.card img {
    width: 40px;
    height: 40px;
    margin-right: 10px;
    object-fit: contain;
}

/* 分类标题样式 */
h2 {
    margin-left: 32px;
    margin-top: 28px;
    margin-bottom: 14px;
    color: #fff;
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: 1px;
    border-left: 5px solid #4CAF50;
    padding-left: 12px;
    background: linear-gradient(90deg,rgba(76,175,80,0.10) 0%,rgba(0,0,0,0) 100%);
    display: inline-block;
    box-shadow: 0 1px 4px rgba(76,175,80,0.06);
    border-radius: 3px;
    line-height: 1.6;
}

h2 > .category-icon {
    margin-right: 6px;
    font-size: 1.2em;
    vertical-align: middle;
}

/* 未找到结果提示 */
.no-results {
    text-align: center;
    margin: 20px;
    contain: content;
}

/* 页脚样式 */
.footer {
    text-align: center;
    padding: 20px;
    font-size: 14px;
    background-color: rgba(0,0,0,0.3);
    contain: content;
}
.footer a {
    color: #ffffff;
    text-decoration: none;
    transition: opacity 0.2s ease;
}
.footer a:hover {
    opacity: 0.8;
}

/* 管理后台表单样式 */
.container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding-top: 50px;
    contain: content;
}
.admin-form {
    background-color: rgba(255,255,255,0.1);
    padding: 20px;
    border-radius: 10px;
    width: 300px;
    contain: content;
}
.admin-form h2 {
    text-align: center;
    margin-bottom: 20px;
}
.admin-form label {
    color: #ffffff;
}
.admin-form input, .admin-form select {
    width: 100%;
    padding: 5px;
    margin-top: 5px;
    background-color: rgba(255,255,255,0.2);
    border: none;
    border-radius: 4px;
    color: #ffffff;
    transition: background-color 0.2s ease;
}
.admin-form input:focus, .admin-form select:focus {
    background-color: rgba(255,255,255,0.3);
    outline: none;
}
.admin-form button {
    width: 100%;
    padding: 8px;
    margin-top: 10px;
    background-color: #4CAF50;
    border: none;
    border-radius: 5px;
    color: white;
    cursor: pointer;
    transition: background-color 0.2s ease;
}
.admin-form button:hover {
    background-color: #45a049;
}
.admin-form .error {
    color: #ff6868;
    text-align: center;
}
.admin-form .success {
    color: #80ff80;
    text-align: center;
}

/* 卡片点击反馈动画 */
.card.active {
    transform: scale(0.97);
    box-shadow: 0 1px 2px rgba(0,0,0,0.18);
    transition: transform 0.1s, box-shadow 0.1s;
}

/* 返回顶部按钮 */
#backTopBtn {
    position: fixed;
    right: 24px;
    bottom: 32px;
    display: none;
    z-index: 999;
    background: #4CAF50;
    color: #fff;
    border: none;
    border-radius: 50%;
    width: 44px;
    height: 44px;
    font-size: 1.5rem;
    box-shadow: 0 2px 8px rgba(0,0,0,0.18);
    cursor: pointer;
    transition: opacity 0.3s;
}
#backTopBtn:active {
    background: #388e3c;
}

/* 响应式设计优化 */
@media (max-width: 768px) {
    .card {
        flex: 0 1 90%;
        margin: 8px;
    }
    .search-bar {
        margin: 10px 0;
    }
    #searchInput {
        width: 95%;
        font-size: 1rem;
    }
    h2 {
        font-size: 1.1rem;
        margin-left: 8px;
        padding-left: 8px;
    }
}

@media (max-width: 480px) {
    .card {
        flex: 0 1 100%;
        margin: 6px 0;
    }
    .search-engines button {
        padding: 6px 10px;
        font-size: 14px;
    }
    #backTopBtn {
        right: 10px;
        bottom: 16px;
        width: 36px;
        height: 36px;
        font-size: 1.1rem;
    }
}

/* 可访问性相关样式 */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 16px;
    background: #4CAF50;
    color: white;
    padding: 10px 18px;
    border-radius: 6px;
    font-size: 18px;
    font-weight: bold;
    z-index: 100;
    transition: top 0.2s ease, box-shadow 0.2s;
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.skip-link:focus {
    top: 16px;
    box-shadow: 0 4px 16px rgba(0,0,0,0.25);
}

/* 键盘焦点样式 */
:focus {
    outline: 3px solid #4CAF50;
    outline-offset: 2px;
}

:focus:not(:focus-visible) {
    outline: none;
}

:focus-visible {
    outline: 3px solid #4CAF50;
    outline-offset: 2px;
}

/* 高对比度模式支持 */
@media (forced-colors: active) {
    .card {
        border: 1px solid CanvasText;
    }
    
    .search-engines button {
        border: 1px solid CanvasText;
    }
    
    #searchInput {
        border: 1px solid CanvasText;
    }
}

/* 减少动画 */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}