/* ===== 基础重置 ===== */
*,
*::before,
*::after {
  box-sizing: border-box; /* 使用更直观的盒模型 */
  margin: 0;
  padding: 0;
}

/* ===== 根元素设置 ===== */
:root {
  /* 字体设置 */
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
  Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
  'Liberation Mono', 'Courier New', monospace;

  /* 颜色变量 */
  --color-primary: #3a86ff;
  --color-secondary: #8338ec;
  --color-accent: #ff006e;
  --color-text: #333;
  --color-light: #f8f9fa;
  --color-dark: #212529;
  --color-gray: #6c757d;

  /* 响应式基础大小 */
  --base-font-size: 16px;
  --spacing-unit: 1rem;

  /* 过渡动画 */
  --transition-speed: 0.3s;
}

/* ===== 基础HTML元素样式 ===== */
html {
  scroll-behavior: smooth; /* 平滑滚动 */
  font-size: var(--base-font-size);
  line-height: 1.6;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background-color: var(--color-light);
  -webkit-font-smoothing: antialiased; /* 字体抗锯齿 */
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* ===== 排版元素 ===== */
h1, h2, h3, h4, h5, h6 {
  line-height: 1.2;
  margin-bottom: var(--spacing-unit);
  font-weight: 700;
}

p {
  margin-bottom: var(--spacing-unit);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-speed);
}

a:hover {
  color: var(--color-secondary);
  text-decoration: underline;
}

/* ===== 表单元素 ===== */
input,
button,
textarea,
select {
  font: inherit; /* 继承字体设置 */
  margin: 0;
}

button {
  cursor: pointer;
  background-color: transparent;
  border: none;
}

/* ===== 图片和媒体 ===== */
img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

/* ===== 实用工具类 ===== */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 calc(var(--spacing-unit) * 1.5);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ===== 响应式媒体查询 ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

@media (min-width: 768px) {
  :root {
    --base-font-size: 16px;
  }
}