CSS 架构与样式方案：从方法论到现代 CSS 新特性

/* 现代轻量 Reset 的核心 */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  line-height: 1.5;
  font-family: system-ui, -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

img,
picture,
video {
  max-width: 100%;
  display: block;
}

button,
input,
select,
textarea {
  font: inherit;
}

/* BEM 命名示例 */
.product-card__title {
  font-size: 1.125rem;
  font-weight: 600;
}

.product-card--featured {
  border-color: var(--color-accent);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

/* Button.module.css */
.root {
  padding: 0.5rem 1rem;
  border-radius: 6px;
  background: var(--color-primary);
}

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

.secondary {
  background: var(--color-gray-200);
}

// Button.tsx
import styles from './Button.module.css';

export function Button({ variant = 'primary', children }) {
  return (
    <button className={`${styles.root} ${styles[variant]}`}>
      {children}
    </button>
  );
}

import styled from 'styled-components';

const Button = styled.button<{ $variant?: 'primary' | 'secondary' }>`
  padding: 0.5rem 1rem;
  border-radius: 6px;
  border: none;
  cursor: pointer;

  ${(props) =>
    props.$variant === 'primary'
      ? css`background: ${props.theme.colors.primary}; color: #fff;`
      : css`background: transparent; color: ${props.theme.colors.text};`}
`;

export function App() {
  return <Button $variant="primary">提交</Button>;
}

// Button.css.ts
import { style, styleVariants, createVar } from '@vanilla-extract/css';

export const accent = createVar();

export const root = style({
  padding: '0.5rem 1rem',
  borderRadius: 6,
  background: accent,
});

export const variant = styleVariants({
  primary: { background: 'var(--color-primary)' },
  secondary: { background: 'var(--color-gray-200)' },
});

// tailwind.config.js
/** @type {import('tailwindcss').Config} */
export default {
  content: ['./src/**/*.{html,js,ts,jsx,tsx}'],
  theme: {
    extend: {
      colors: {
        brand: {
          50: '#eef2ff',
          500: '#6366f1',
          700: '#4338ca',
        },
      },
      spacing: {
        18: '4.5rem',
      },
    },
  },
  darkMode: 'class', // 通过 class 切换暗色模式
  plugins: [],
};

<!-- utility 组合 -->
<button
  class="rounded-lg bg-brand-500 px-4 py-2 text-white hover:bg-brand-700 focus-visible:outline-2 focus-visible:outline-brand-700"
>
  提交
</button>

# 产物分析
npm run build
# → styles.css 可能只有 10-30KB（gzip 前）

:root {
  /* 色彩层级 */
  --color-brand-500: #6366f1;
  --color-text-primary: #1f2937;
  --color-text-secondary: #6b7280;
  --color-bg-canvas: #ffffff;

  /* 间距 */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-4: 1rem;

  /* 字体 */
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --radius-md: 0.5rem;

  /* 阴影 */
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.1);
}

/* 亮色主题 */
:root {
  --color-bg-primary: var(--color-white);
  --color-text-primary: var(--color-gray-900);
}

/* 暗色主题：只覆盖语义映射 */
.dark {
  --color-bg-primary: var(--color-gray-900);
  --color-text-primary: var(--color-gray-100);
}

import { useEffect, useState } from 'react';

function useTheme() {
  const [theme, setTheme] = useState<'light' | 'dark'>(() => {
    const saved = localStorage.getItem('theme');
    if (saved === 'light' || saved === 'dark') return saved;
    return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
  });

  useEffect(() => {
    document.documentElement.classList.toggle('dark', theme === 'dark');
    localStorage.setItem('theme', theme);
  }, [theme]);

  return [theme, setTheme] as const;
}

<script>
  (function () {
    var saved = localStorage.getItem('theme');
    var dark = saved === 'dark' ||
      (!saved && window.matchMedia('(prefers-color-scheme: dark)').matches);
    document.documentElement.classList.toggle('dark', dark);
  })();
</script>

/* 声明容器 */
.card-grid {
  container-type: inline-size;
  container-name: card-container;
}

/* 基于容器宽度的样式 */
@container card-container (min-width: 400px) {
  .card {
    display: grid;
    grid-template-columns: 1fr 2fr;
  }
}

<div class="card-grid">
  <article class="card">
    <img class="card__media" src="..." alt="..." />
    <div class="card__body">…</div>
  </article>
</div>

.page {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1rem;
}

.card-row {
  grid-column: 1 / -1;
  display: grid;
  grid-template-columns: subgrid; /* 继承 12 列 */
}

.card {
  grid-column: span 4; /* 在子网格中按 12 列布局 */
}

{
  "prettier": {
    "plugins": ["prettier-plugin-tailwindcss"]
  }
}