*, *::before, *::after { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 var(--font);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  overflow-y: auto;
  transition: background-color 0.3s ease, color 0.3s ease;
}

h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 0.5em; font-weight: 600; }
h1 { font-size: 1.75rem; }
h2 { font-size: 1.35rem; }
h3 { font-size: 1.1rem; }
p { margin: 0 0 1em; }

a { color: var(--primary); text-decoration: underline; text-underline-offset: 2px; }
a:hover { color: var(--primary-hover); }

code, kbd, pre { font-family: var(--font-mono); font-size: 0.92em; }
code { background: var(--surface-2); padding: 0.1em 0.35em; border-radius: var(--radius-sm); }
pre { background: var(--surface-2); padding: 0.8em 1em; border-radius: var(--radius); overflow-x: auto; }
pre code { background: none; padding: 0; }

hr { border: 0; border-top: 1px solid var(--border); margin: 1.5em 0; }

:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; }

.container-wide { width: 100%; max-width: 1280px; margin: 0 auto; padding-left: 16px; padding-right: 16px; }
.container { width: 100%; max-width: 1080px; margin: 0 auto; padding-left: 16px; padding-right: 16px; }

/* 无障碍 */
.sr-only {
  position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
.skip-link {
  position: absolute; left: 8px; top: -48px; z-index: 100;
  background: var(--primary); color: var(--primary-text);
  padding: 8px 14px; border-radius: var(--radius-sm); transition: top 0.15s;
}
.skip-link:focus { top: 8px; color: var(--primary-text); }

/* 常用布局小工具（页面里不使用内联 style，以便保持严格 CSP） */
.stack { display: flex; flex-direction: column; gap: 16px; }
.stack-sm { display: flex; flex-direction: column; gap: 8px; }
.row { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.row-between { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; }
.grow { flex: 1 1 auto; }
.muted { color: var(--text-muted); }
.small { font-size: 0.875rem; }
.text-right { text-align: right; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; animation: none !important; }
}