/* ========================================
   CSS Reset & Base Styles
   ======================================== */

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

:root {
    /* 配色 */
    --color-bg: #ffffff;
    --color-text-primary: #1d1d1f;
    --color-text-secondary: #6e6e73;
    --color-accent: #0071e3;
    --color-code-bg: #f5f5f7;
    --color-border: #d2d2d7;
    --color-demo-bg: #fafafa;

    /* 字体 */
    --font-system: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display",
                   "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;

    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;
    --spacing-xxl: 6rem;

    /* 圆角 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 18px;

    /* 阴影 */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-system);
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========================================
   导航栏
   ======================================== */

/* .navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid var(--color-border);
    padding: 1rem 0;
    transition: all 0.3s ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text-primary);
    letter-spacing: -0.01em;
}

.nav-author {
    font-size: 0.938rem;
    color: var(--color-text-secondary);
} */

/* ========================================
   内容区域
   ======================================== */

.main-content {
    max-width: 980px;
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-md);
}

/* ========================================
   头部英雄区域
   ======================================== */

.hero {
    text-align: center;
    padding: var(--spacing-xxl) 0 var(--spacing-xl);
    animation: fadeInUp 0.8s ease-out;
}

.main-title {
    font-size: 3.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, #1d1d1f 0%, #4a4a4a 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 1.5rem;
    font-weight: 400;
    color: var(--color-text-secondary);
    letter-spacing: -0.01em;
}

/* ========================================
   文章内容
   ======================================== */

.article-content {
    animation: fadeIn 1s ease-out;
}

.section {
    margin-bottom: var(--spacing-xl);
    animation: fadeInUp 0.6s ease-out;
    animation-fill-mode: both;
}

.section:nth-child(1) { animation-delay: 0.1s; }
.section:nth-child(2) { animation-delay: 0.2s; }
.section:nth-child(3) { animation-delay: 0.3s; }
.section:nth-child(4) { animation-delay: 0.4s; }
.section:nth-child(5) { animation-delay: 0.5s; }

.section h2 {
    font-size: 2.25rem;
    font-weight: 700;
    letter-spacing: -0.015em;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.section h3 {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-primary);
}

.section p {
    font-size: 1.125rem;
    line-height: 1.75;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

.lead-text {
    font-size: 1.375rem !important;
    font-weight: 400;
    line-height: 1.6 !important;
    color: var(--color-text-secondary);
}

/* ========================================
   代码样式
   ======================================== */

.inline-code {
    background-color: var(--color-code-bg);
    color: var(--color-accent);
    padding: 0.2em 0.5em;
    border-radius: 4px;
    font-family: "SF Mono", Monaco, Menlo, Consolas, "Courier New", monospace;
    font-size: 0.9em;
    font-weight: 500;
}

.code-block-wrapper {
    margin: var(--spacing-md) 0;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    position: relative;
}

.code-block {
    display: block;
    background-color: #fafafa;
    color: #383a42;
    padding: var(--spacing-md);
    font-family: "SF Mono", Monaco, Menlo, Consolas, "Courier New", monospace;
    font-size: 0.938rem;
    line-height: 1.6;
    overflow-x: auto;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
}

/* ========================================
   SVG 演示区域
   ======================================== */

.svg-demo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background-color: var(--color-demo-bg);
    border-radius: var(--radius-lg);
    margin: var(--spacing-md) 0;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.svg-demo:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.demo-label {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text-secondary);
}

.demo-svg {
    filter: drop-shadow(0 2px 8px rgba(0, 0, 0, 0.1));
    transition: transform 0.3s ease;
}

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

/* ========================================
   代码解释区域
   ======================================== */

.code-breakdown {
    margin: var(--spacing-xl) 0;
}

.code-breakdown h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-lg);
}

.breakdown-list {
    margin: 0;
    padding: 0;
}

.breakdown-list dt {
    font-weight: 600;
    color: var(--color-accent);
    margin-top: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);
}

.breakdown-list dt:first-of-type {
    margin-top: 0;
}

.breakdown-list dd {
    margin: var(--spacing-md) 0 0 0;
    padding-left: var(--spacing-md);
}

.breakdown-list dd p {
    margin-bottom: var(--spacing-sm);
}

.breakdown-list dd ul {
    margin: var(--spacing-sm) 0;
    padding-left: var(--spacing-lg);
}

.breakdown-list dd li {
    margin-bottom: var(--spacing-xs);
    line-height: 1.75;
}

.note {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    border-left: 3px solid var(--color-accent);
    background-color: var(--color-demo-bg);
    line-height: 1.75;
}

/* ========================================
   特殊区块
   ======================================== */

.w3c-section {
    background: linear-gradient(135deg, #fafafa 0%, #f5f5f7 100%);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.conclusion {
    text-align: center;
    padding: var(--spacing-xl) var(--spacing-md);
}

.closing-text {
    font-size: 1.25rem !important;
    line-height: 1.6 !important;
    color: var(--color-text-secondary);
    font-weight: 400;
    max-width: 800px;
    margin: 0 auto;
}

/* ========================================
   页脚
   ======================================== */

.footer {
    background-color: var(--color-demo-bg);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-lg) 0;
    margin-top: var(--spacing-xxl);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    text-align: center;
}

.footer-content p {
    color: var(--color-text-secondary);
    font-size: 0.938rem;
}

/* ========================================
   动画
   ======================================== */

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========================================
   响应式设计
   ======================================== */

/* 平板设备 */
@media (max-width: 1024px) {
    .main-title {
        font-size: 2.75rem;
    }

    .subtitle {
        font-size: 1.25rem;
    }

    .section h2 {
        font-size: 2rem;
    }

    .section p {
        font-size: 1.063rem;
    }
}

/* 手机 */
@media (max-width: 768px) {
    :root {
        --spacing-md: 1.5rem;
        --spacing-lg: 2rem;
        --spacing-xl: 3rem;
        --spacing-xxl: 4rem;
    }

    .nav-container {
        flex-direction: column;
        gap: var(--spacing-xs);
        text-align: center;
    }

    .hero {
        padding: var(--spacing-lg) 0 var(--spacing-md);
    }

    .main-title {
        font-size: 2.25rem;
        line-height: 1.2;
    }

    .subtitle {
        font-size: 1.125rem;
    }

    .section {
        margin-bottom: var(--spacing-lg);
    }

    .section h2 {
        font-size: 1.75rem;
    }

    .section h3 {
        font-size: 1.25rem;
    }

    .section p {
        font-size: 1rem;
    }

    .lead-text {
        font-size: 1.188rem !important;
    }

    .closing-text {
        font-size: 1.125rem !important;
    }

    .code-block {
        font-size: 0.875rem;
        padding: var(--spacing-sm);
    }

    .svg-demo {
        flex-direction: column;
        padding: var(--spacing-md);
    }

    .code-breakdown,
    .w3c-section {
        /* padding: var(--spacing-md); */
        padding: 1em;
    }
}

/* 小屏手机 */
@media (max-width: 480px) {
    html {
        font-size: 14px;
    }

    .main-title {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .section h2 {
        font-size: 1.5rem;
    }

    .code-block {
        font-size: 0.813rem;
    }
}

/* ========================================
   深色模式支持
   ======================================== */

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #000000;
        --color-text-primary: #f5f5f7;
        --color-text-secondary: #a1a1a6;
        --color-accent: #2997ff;
        --color-code-bg: #1d1d1f;
        --color-border: #424245;
        --color-demo-bg: #1d1d1f;
    }

    .navbar {
        background-color: rgba(0, 0, 0, 0.8);
    }

    .main-title {
        background: linear-gradient(135deg, #f5f5f7 0%, #a1a1a6 100%);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        background-clip: text;
    }

    .code-block {
        background-color: #282c34;
        color: #abb2bf;
        border-color: #424245;
    }

    .w3c-section {
        background: linear-gradient(135deg, #1d1d1f 0%, #2d2d2d 100%);
    }
}

/* ========================================
   打印样式
   ======================================== */

@media print {
    .navbar,
    .footer {
        display: none;
    }

    .main-content {
        max-width: 100%;
        padding: 0;
    }

    .section {
        page-break-inside: avoid;
    }
}