/* ============================================================
   base.css — 设计变量、reset、排版
   ============================================================ */
:root {
  --c-primary: #1666d9;
  --c-primary-dark: #0f4fb0;
  --c-primary-light: #e8f0fe;
  --c-accent: #0aa36f;
  --c-accent-dark: #078157;

  --c-bg: #f4f6fa;
  --c-surface: #ffffff;
  --c-text: #1f2933;
  --c-text-2: #52606d;
  --c-text-3: #7b8794;
  --c-border: #e2e8f0;
  --c-danger: #d64545;

  --radius-sm: 6px;
  --radius: 10px;
  --radius-lg: 14px;

  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06);
  --shadow: 0 4px 16px rgba(16, 24, 40, 0.08);

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;

  --maxw: 1080px;
}

* {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.6;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
h4,
p {
  margin: 0;
}

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

a:hover {
  text-decoration: underline;
}

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

button {
  font-family: inherit;
}

/* 键盘焦点可见性（无障碍） */
:focus-visible {
  outline: 2px solid var(--c-primary);
  outline-offset: 2px;
  border-radius: 4px;
}

/* 屏幕阅读器专用文本 */
.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}