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CSS高级特性

cheniy2025/9/17大约 14 分钟CSSCSS3动画变换高级特性

CSS高级特性

学习目标

  • 掌握CSS3的新特性和高级功能
  • 学会使用CSS动画和过渡效果
  • 了解CSS变换和滤镜效果
  • 掌握现代CSS开发技巧

CSS3新特性

圆角边框 - border-radius

CSS3引入的圆角功能让我们能够轻松创建圆角元素。

点击展开示例
/* 基础圆角设置 */
.basic-radius {
    border-radius: 10px;            /* 四个角相同圆角 */
    background-color: #3498db;
    color: white;
    padding: 20px;
    margin: 10px;
}

/* 分别设置四个角 */
.custom-radius {
    border-top-left-radius: 10px;      /* 左上角 */
    border-top-right-radius: 20px;     /* 右上角 */
    border-bottom-right-radius: 30px;  /* 右下角 */
    border-bottom-left-radius: 40px;   /* 左下角 */
    
    /* 简写形式：左上 右上 右下 左下 */
    border-radius: 10px 20px 30px 40px;
}

/* 椭圆形圆角 */
.elliptical-radius {
    border-radius: 50px / 25px;     /* 水平半径 / 垂直半径 */
    width: 200px;
    height: 100px;
    background-color: #e74c3c;
}

/* 实用圆角样式 */
.card {
    border-radius: 12px;            /* 现代卡片圆角 */
    background: white;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    padding: 24px;
    margin: 16px;
}

.button {
    border-radius: 6px;             /* 按钮圆角 */
    padding: 12px 24px;
    background-color: #2ecc71;
    color: white;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
}

.button:hover {
    border-radius: 8px;             /* 悬停时稍微增加圆角 */
    transform: translateY(-2px);
}

.avatar {
    border-radius: 50%;             /* 圆形头像 */
    width: 80px;
    height: 80px;
    object-fit: cover;
}

.pill {
    border-radius: 25px;            /* 胶囊形状 */
    padding: 8px 20px;
    background-color: #9b59b6;
    color: white;
    display: inline-block;
}

/* 不规则圆角 */
.organic-shape {
    border-radius: 63% 37% 54% 46% / 55% 48% 52% 45%;
    width: 200px;
    height: 200px;
    background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
    animation: morphing 8s ease-in-out infinite;
}

@keyframes morphing {
    0%, 100% {
        border-radius: 63% 37% 54% 46% / 55% 48% 52% 45%;
    }
    25% {
        border-radius: 40% 60% 60% 40% / 60% 30% 70% 40%;
    }
    50% {
        border-radius: 54% 46% 38% 62% / 49% 70% 30% 51%;
    }
    75% {
        border-radius: 61% 39% 55% 45% / 61% 38% 62% 39%;
    }
}

阴影效果 - box-shadow

阴影效果为元素添加深度和层次感。

点击展开示例
/* 基础阴影语法：x偏移 y偏移 模糊半径 扩展半径 颜色 */
.basic-shadow {
    box-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
    padding: 20px;
    background: white;
    margin: 20px;
}

/* 多重阴影 */
.multiple-shadows {
    box-shadow: 
        0 1px 3px rgba(0, 0, 0, 0.12),     /* 细微阴影 */
        0 1px 2px rgba(0, 0, 0, 0.24);     /* 主要阴影 */
    padding: 20px;
    background: white;
}

/* 内阴影 */
.inset-shadow {
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.1);
    padding: 20px;
    background: #f8f9fa;
    border-radius: 8px;
}

/* 发光效果 */
.glow-effect {
    box-shadow: 0 0 20px rgba(52, 152, 219, 0.5);
    background-color: #3498db;
    color: white;
    padding: 20px;
    border-radius: 8px;
    transition: box-shadow 0.3s ease;
}

.glow-effect:hover {
    box-shadow: 0 0 30px rgba(52, 152, 219, 0.8);
}

/* 材质设计阴影 */
.material-shadow-1 {
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
}

.material-shadow-2 {
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.16), 0 3px 6px rgba(0, 0, 0, 0.23);
}

.material-shadow-3 {
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
}

.material-shadow-4 {
    box-shadow: 0 14px 28px rgba(0, 0, 0, 0.25), 0 10px 10px rgba(0, 0, 0, 0.22);
}

.material-shadow-5 {
    box-shadow: 0 19px 38px rgba(0, 0, 0, 0.30), 0 15px 12px rgba(0, 0, 0, 0.22);
}

/* 悬浮卡片效果 */
.hover-card {
    background: white;
    border-radius: 12px;
    padding: 24px;
    transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    cursor: pointer;
}

.hover-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.15);
}

/* 彩色阴影 */
.colored-shadow {
    background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
    color: white;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 8px 32px rgba(255, 107, 107, 0.3);
    transition: all 0.3s ease;
}

.colored-shadow:hover {
    box-shadow: 0 12px 48px rgba(255, 107, 107, 0.4);
    transform: translateY(-4px);
}

渐变背景 - gradient

点击展开示例
/* 线性渐变 */
.linear-gradient {
    background: linear-gradient(to right, #ff6b6b, #4ecdc4);
    height: 100px;
    border-radius: 8px;
}

/* 指定角度的线性渐变 */
.angled-gradient {
    background: linear-gradient(45deg, #667eea, #764ba2);
    height: 100px;
    border-radius: 8px;
}

/* 多色渐变 */
.multi-color-gradient {
    background: linear-gradient(
        90deg,
        #ff6b6b 0%,
        #feca57 25%,
        #48dbfb 50%,
        #ff9ff3 75%,
        #54a0ff 100%
    );
    height: 100px;
    border-radius: 8px;
}

/* 径向渐变 */
.radial-gradient {
    background: radial-gradient(circle, #ff6b6b, #4ecdc4);
    height: 100px;
    border-radius: 8px;
}

/* 椭圆径向渐变 */
.elliptical-gradient {
    background: radial-gradient(ellipse at center, #667eea, #764ba2);
    height: 100px;
    border-radius: 8px;
}

/* 锥形渐变 */
.conic-gradient {
    background: conic-gradient(from 0deg, #ff6b6b, #feca57, #48dbfb, #ff9ff3, #ff6b6b);
    height: 100px;
    border-radius: 50%;
}

/* 实用渐变样式 */
.gradient-button {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.gradient-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.gradient-button:hover::before {
    opacity: 1;
}

.gradient-button span {
    position: relative;
    z-index: 1;
}

/* 渐变文字 */
.gradient-text {
    background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 2rem;
    font-weight: bold;
}

/* 动态渐变背景 */
.animated-gradient {
    background: linear-gradient(-45deg, #ee7752, #e73c7e, #23a6d5, #23d5ab);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    height: 200px;
    border-radius: 12px;
}

@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

CSS动画

过渡效果 - transition

过渡效果让属性变化更加平滑自然。

点击展开示例
/* 基础过渡语法：属性 持续时间 时间函数 延迟 */
.basic-transition {
    background-color: #3498db;
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.basic-transition:hover {
    background-color: #2980b9;
}

/* 多属性过渡 */
.multi-transition {
    background-color: #e74c3c;
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transform: scale(1);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    
    transition: 
        background-color 0.3s ease,
        transform 0.3s ease,
        box-shadow 0.3s ease;
}

.multi-transition:hover {
    background-color: #c0392b;
    transform: scale(1.05);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
}

/* 所有属性过渡 */
.all-transition {
    transition: all 0.3s ease;
    padding: 15px 30px;
    background-color: #2ecc71;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
}

.all-transition:hover {
    background-color: #27ae60;
    transform: translateY(-3px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}

/* 不同的时间函数 */
.timing-functions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.timing-demo {
    width: 100px;
    height: 50px;
    background-color: #9b59b6;
    margin-bottom: 10px;
    cursor: pointer;
    transition: transform 1s;
}

.ease { transition-timing-function: ease; }
.linear { transition-timing-function: linear; }
.ease-in { transition-timing-function: ease-in; }
.ease-out { transition-timing-function: ease-out; }
.ease-in-out { transition-timing-function: ease-in-out; }
.cubic-bezier { transition-timing-function: cubic-bezier(0.68, -0.55, 0.265, 1.55); }

.timing-demo:hover {
    transform: translateX(200px);
}

/* 延迟过渡 */
.delayed-transition {
    background-color: #f39c12;
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.5s ease 0.2s;    /* 延迟0.2秒 */
}

.delayed-transition:hover {
    background-color: #e67e22;
    transform: scale(1.1);
}

关键帧动画 - @keyframes

关键帧动画提供了更复杂和精确的动画控制。

点击展开示例
/* 基础关键帧动画 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.6s ease-out;
}

/* 百分比关键帧 */
@keyframes bounce {
    0% {
        transform: translateY(0);
    }
    25% {
        transform: translateY(-20px);
    }
    50% {
        transform: translateY(0);
    }
    75% {
        transform: translateY(-10px);
    }
    100% {
        transform: translateY(0);
    }
}

.bounce-animation {
    animation: bounce 1s ease-in-out;
}

/* 无限循环动画 */
@keyframes rotate {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.rotate-infinite {
    animation: rotate 2s linear infinite;
    width: 50px;
    height: 50px;
    background-color: #3498db;
    border-radius: 50%;
}

/* 脉冲动画 */
@keyframes pulse {
    0% {
        transform: scale(1);
        box-shadow: 0 0 0 0 rgba(52, 152, 219, 0.7);
    }
    70% {
        transform: scale(1.05);
        box-shadow: 0 0 0 10px rgba(52, 152, 219, 0);
    }
    100% {
        transform: scale(1);
        box-shadow: 0 0 0 0 rgba(52, 152, 219, 0);
    }
}

.pulse-button {
    background-color: #3498db;
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 6px;
    cursor: pointer;
    animation: pulse 2s infinite;
}

/* 打字机效果 */
@keyframes typing {
    from {
        width: 0;
    }
    to {
        width: 100%;
    }
}

@keyframes blink {
    50% {
        border-color: transparent;
    }
}

.typewriter {
    font-family: 'Courier New', monospace;
    font-size: 1.5rem;
    border-right: 2px solid #333;
    white-space: nowrap;
    overflow: hidden;
    animation: 
        typing 3s steps(30, end),
        blink 0.75s step-end infinite;
}

/* 加载动画 */
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
}

/* 波浪动画 */
@keyframes wave {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

.wave-container {
    display: flex;
    gap: 5px;
    align-items: center;
    justify-content: center;
    height: 60px;
}

.wave-dot {
    width: 10px;
    height: 10px;
    background-color: #3498db;
    border-radius: 50%;
    animation: wave 1.4s ease-in-out infinite;
}

.wave-dot:nth-child(1) { animation-delay: 0s; }
.wave-dot:nth-child(2) { animation-delay: 0.1s; }
.wave-dot:nth-child(3) { animation-delay: 0.2s; }
.wave-dot:nth-child(4) { animation-delay: 0.3s; }
.wave-dot:nth-child(5) { animation-delay: 0.4s; }

/* 动画控制属性 */
.animation-controls {
    animation-name: bounce;
    animation-duration: 2s;             /* 持续时间 */
    animation-timing-function: ease-in-out; /* 时间函数 */
    animation-delay: 0.5s;              /* 延迟 */
    animation-iteration-count: 3;       /* 重复次数 */
    animation-direction: alternate;     /* 方向：normal, reverse, alternate, alternate-reverse */
    animation-fill-mode: forwards;      /* 填充模式：none, forwards, backwards, both */
    animation-play-state: running;      /* 播放状态：running, paused */
}

/* 简写形式 */
.animation-shorthand {
    animation: bounce 2s ease-in-out 0.5s 3 alternate forwards;
}

变换 - transform

点击展开示例
/* 2D变换 */
.transform-demo {
    width: 100px;
    height: 100px;
    background-color: #e74c3c;
    margin: 50px;
    transition: transform 0.3s ease;
}

/* 平移 */
.translate {
    transform: translate(50px, 30px);   /* X轴50px, Y轴30px */
}

.translateX {
    transform: translateX(50px);        /* 只在X轴平移 */
}

.translateY {
    transform: translateY(30px);        /* 只在Y轴平移 */
}

/* 缩放 */
.scale {
    transform: scale(1.5);              /* 等比例缩放1.5倍 */
}

.scaleX {
    transform: scaleX(2);               /* X轴缩放2倍 */
}

.scaleY {
    transform: scaleY(0.5);             /* Y轴缩放0.5倍 */
}

.scale-xy {
    transform: scale(1.5, 0.8);         /* X轴1.5倍，Y轴0.8倍 */
}

/* 旋转 */
.rotate {
    transform: rotate(45deg);           /* 顺时针旋转45度 */
}

.rotate-negative {
    transform: rotate(-30deg);          /* 逆时针旋转30度 */
}

/* 倾斜 */
.skew {
    transform: skew(20deg, 10deg);      /* X轴倾斜20度，Y轴倾斜10度 */
}

.skewX {
    transform: skewX(20deg);            /* 只在X轴倾斜 */
}

.skewY {
    transform: skewY(10deg);            /* 只在Y轴倾斜 */
}

/* 组合变换 */
.combined-transform {
    transform: translate(50px, 30px) rotate(45deg) scale(1.2);
}

/* 变换原点 */
.transform-origin-demo {
    width: 100px;
    height: 100px;
    background-color: #3498db;
    margin: 50px;
    transition: transform 0.3s ease;
}

.origin-center {
    transform-origin: center;           /* 默认值 */
    transform: rotate(45deg);
}

.origin-top-left {
    transform-origin: top left;
    transform: rotate(45deg);
}

.origin-bottom-right {
    transform-origin: bottom right;
    transform: rotate(45deg);
}

.origin-custom {
    transform-origin: 20px 30px;        /* 自定义原点 */
    transform: rotate(45deg);
}

/* 3D变换 */
.transform-3d {
    perspective: 1000px;                /* 设置透视距离 */
    width: 200px;
    height: 200px;
    margin: 100px auto;
}

.cube-3d {
    width: 100px;
    height: 100px;
    background-color: #9b59b6;
    transform-style: preserve-3d;       /* 保持3D效果 */
    transition: transform 1s ease;
}

.cube-3d:hover {
    transform: rotateX(45deg) rotateY(45deg);
}

/* 3D翻转卡片 */
.flip-card {
    background-color: transparent;
    width: 200px;
    height: 200px;
    perspective: 1000px;
    margin: 50px;
}

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

.flip-card:hover .flip-card-inner {
    transform: rotateY(180deg);
}

.flip-card-front, .flip-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
}

.flip-card-front {
    background-color: #3498db;
}

.flip-card-back {
    background-color: #e74c3c;
    transform: rotateY(180deg);
}

滤镜效果

点击展开示例
/* CSS滤镜效果 */
.filter-demo {
    width: 200px;
    height: 150px;
    background-image: url('demo-image.jpg');
    background-size: cover;
    background-position: center;
    margin: 10px;
    border-radius: 8px;
    transition: filter 0.3s ease;
}

/* 模糊效果 */
.blur {
    filter: blur(5px);
}

.blur:hover {
    filter: blur(0);
}

/* 亮度调整 */
.brightness {
    filter: brightness(1.5);           /* 增加亮度 */
}

.brightness-dark {
    filter: brightness(0.5);           /* 降低亮度 */
}

/* 对比度调整 */
.contrast {
    filter: contrast(1.5);             /* 增加对比度 */
}

/* 饱和度调整 */
.saturate {
    filter: saturate(2);               /* 增加饱和度 */
}

.desaturate {
    filter: saturate(0);               /* 去色（黑白） */
}

/* 色相旋转 */
.hue-rotate {
    filter: hue-rotate(90deg);         /* 色相旋转90度 */
}

/* 反色 */
.invert {
    filter: invert(1);                 /* 完全反色 */
}

.invert-partial {
    filter: invert(0.5);               /* 部分反色 */
}

/* 透明度 */
.opacity-filter {
    filter: opacity(0.5);              /* 50%透明度 */
}

/* 阴影滤镜 */
.drop-shadow {
    filter: drop-shadow(4px 4px 8px rgba(0, 0, 0, 0.3));
}

/* 组合滤镜 */
.combined-filter {
    filter: brightness(1.2) contrast(1.1) saturate(1.3);
}

.combined-filter:hover {
    filter: brightness(1) contrast(1) saturate(1) blur(0);
}

/* 实用滤镜效果 */
.image-hover-effects {
    overflow: hidden;
    border-radius: 12px;
}

.image-hover-effects img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    transition: all 0.3s ease;
    filter: brightness(0.8) contrast(1.2);
}

.image-hover-effects:hover img {
    transform: scale(1.1);
    filter: brightness(1) contrast(1) saturate(1.2);
}

/* 毛玻璃效果 */
.glass-effect {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    padding: 20px;
    color: white;
}

现代CSS技术

CSS变量（自定义属性）

点击展开示例
/* 定义CSS变量 */
:root {
    /* 颜色变量 */
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    
    /* 尺寸变量 */
    --border-radius: 8px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    
    /* 字体变量 */
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-sm: 14px;
    --font-size-md: 16px;
    --font-size-lg: 18px;
    
    /* 间距变量 */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
}

/* 使用CSS变量 */
.button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    padding: var(--spacing-sm) var(--spacing-md);
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    box-shadow: var(--box-shadow);
    transition: var(--transition);
    cursor: pointer;
}

.button:hover {
    background-color: var(--secondary-color);
    transform: translateY(-2px);
}

/* 主题切换 */
.theme-light {
    --bg-color: #ffffff;
    --text-color: #333333;
    --border-color: #e0e0e0;
}

.theme-dark {
    --bg-color: #1a1a1a;
    --text-color: #ffffff;
    --border-color: #404040;
}

.themed-component {
    background-color: var(--bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

/* 动态变量 */
.dynamic-color {
    --hue: 200;
    background-color: hsl(var(--hue), 70%, 50%);
    transition: background-color 0.3s ease;
}

.dynamic-color:hover {
    --hue: 300;
}

CSS Grid布局

点击展开示例
/* 基础Grid布局 */
.grid-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);  /* 三列等宽 */
    grid-template-rows: auto;
    gap: 20px;
    padding: 20px;
}

.grid-item {
    background-color: #3498db;
    color: white;
    padding: 20px;
    border-radius: 8px;
    text-align: center;
}

/* 复杂Grid布局 */
.complex-grid {
    display: grid;
    grid-template-columns: 200px 1fr 150px;
    grid-template-rows: 60px 1fr 40px;
    grid-template-areas:
        "header header header"
        "sidebar main aside"
        "footer footer footer";
    gap: 10px;
    min-height: 100vh;
}

.grid-header {
    grid-area: header;
    background-color: #2c3e50;
    color: white;
    display: flex;
    align-items: center;
    padding: 0 20px;
}

.grid-sidebar {
    grid-area: sidebar;
    background-color: #ecf0f1;
    padding: 20px;
}

.grid-main {
    grid-area: main;
    background-color: white;
    padding: 20px;
}

.grid-aside {
    grid-area: aside;
    background-color: #f8f9fa;
    padding: 20px;
}

.grid-footer {
    grid-area: footer;
    background-color: #34495e;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* 响应式Grid */
.responsive-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    padding: 20px;
}

.responsive-grid-item {
    background-color: #e74c3c;
    color: white;
    padding: 20px;
    border-radius: 8px;
    min-height: 200px;
}

现代CSS选择器

点击展开示例
/* 属性选择器 */
input[type="email"] {
    border: 2px solid #3498db;
}

input[placeholder*="密码"] {
    border: 2px solid #e74c3c;
}

a[href^="https://"] {
    color: #2ecc71;
}

a[href$=".pdf"] {
    color: #e74c3c;
}

/* 结构伪类选择器 */
.list-item:nth-child(odd) {
    background-color: #f8f9fa;
}

.list-item:nth-child(even) {
    background-color: #ffffff;
}

.list-item:nth-child(3n) {
    border-left: 4px solid #3498db;
}

.list-item:first-child {
    border-top-left-radius: 8px;
    border-top-right-radius: 8px;
}

.list-item:last-child {
    border-bottom-left-radius: 8px;
    border-bottom-right-radius: 8px;
}

.list-item:only-child {
    border-radius: 8px;
}

/* 状态伪类选择器 */
input:focus {
    outline: none;
    border-color: #3498db;
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.25);
}

input:valid {
    border-color: #2ecc71;
}

input:invalid {
    border-color: #e74c3c;
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* 伪元素选择器 */
.quote::before {
    content: '"';
    font-size: 2em;
    color: #3498db;
}

.quote::after {
    content: '"';
    font-size: 2em;
    color: #3498db;
}

.tooltip {
    position: relative;
}

.tooltip::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background-color: #333;
    color: white;
    padding: 8px 12px;
    border-radius: 4px;
    font-size: 14px;
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.tooltip:hover::after {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(-5px);
}

最佳实践与性能优化

1. 动画性能优化

点击展开示例
/* 使用transform和opacity进行动画（GPU加速） */
.optimized-animation {
    /* 好的做法 */
    transform: translateX(100px);
    opacity: 0.5;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

/* 避免动画这些属性（会触发重排） */
.avoid-animation {
    /* 避免 */
    left: 100px;
    width: 200px;
    height: 100px;
}

/* 使用will-change提示浏览器 */
.will-change-demo {
    will-change: transform, opacity;
    transition: transform 0.3s ease;
}

.will-change-demo:hover {
    transform: scale(1.1);
}

/* 动画完成后移除will-change */
.animation-complete {
    will-change: auto;
}

2. CSS组织和维护

点击展开示例
/* 使用BEM命名规范 */
.card {
    /* 块 */
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.card__header {
    /* 元素 */
    padding: 20px 20px 0;
    border-bottom: 1px solid #eee;
}

.card__title {
    /* 元素 */
    margin: 0;
    font-size: 1.25rem;
}

.card__body {
    /* 元素 */
    padding: 20px;
}

.card--featured {
    /* 修饰符 */
    border: 2px solid #3498db;
}

.card--large {
    /* 修饰符 */
    max-width: 600px;
}

/* 使用CSS自定义属性进行主题管理 */
.component {
    background-color: var(--component-bg, #ffffff);
    color: var(--component-text, #333333);
    border: 1px solid var(--component-border, #e0e0e0);
}

/* 响应式设计的最佳实践 */
.responsive-component {
    /* 移动优先 */
    padding: var(--spacing-sm);
    font-size: var(--font-size-sm);
}

@media (min-width: 768px) {
    .responsive-component {
        padding: var(--spacing-md);
        font-size: var(--font-size-md);
    }
}

@media (min-width: 1024px) {
    .responsive-component {
        padding: var(--spacing-lg);
        font-size: var(--font-size-lg);
    }
}

3. 可访问性和用户体验

点击展开示例
/* 尊重用户的动画偏好 */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* 高对比度模式支持 */
@media (prefers-contrast: high) {
    .button {
        border: 2px solid currentColor;
    }
}

/* 焦点管理 */
.focus-visible {
    outline: 2px solid #3498db;
    outline-offset: 2px;
}

/* 确保足够的颜色对比度 */
.accessible-text {
    color: #333333;                 /* 4.5:1 对比度 */
    background-color: #ffffff;
}

/* 触摸友好的设计 */
@media (pointer: coarse) {
    .touch-target {
        min-height: 44px;
        min-width: 44px;
        padding: 12px;
    }
}

总结

本章我们学习了CSS的高级特性，包括CSS3新特性、动画效果、变换、滤镜以及现代CSS技术。这些技术让我们能够创建更加丰富、动态和现代化的网页界面。

关键要点：

  • CSS3提供了丰富的视觉效果和动画能力
  • 合理使用动画和过渡可以提升用户体验
  • 性能优化和可访问性同样重要
  • 现代CSS技术如变量、Grid布局提供了更好的开发体验
  • 始终考虑用户的需求和设备限制

通过掌握这些CSS技术，你已经具备了创建现代化、响应式和用户友好的网页界面的能力。继续实践和探索，你将能够创造出更加出色的网页作品！

最近更新
贡献者: cheniy