:root {
  --max-w: 720px;
  --pad: 1rem;
  --gap: 1rem;
  --line: 1.6;
  --sans: system-ui, -apple-system, "Segoe UI", "Helvetica Neue", "Noto Sans CJK SC", "Microsoft YaHei", sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --border: #ddd;
  --warn: #b00;
  --err: #c00;
  --muted: #666;
  --bg-soft: #f6f6f6;
  --bg-warn: #fff7f6;
}

/* FOUC suppression for ZH startup */
html[data-lang="zh"]:not([data-i18n-ready]) [data-i18n]:not([data-i18n-pre]),
html[data-lang="zh"]:not([data-i18n-ready]) [data-i18n-html]:not([data-i18n-pre]) {
  visibility: hidden;
}

* { box-sizing: border-box; }

body {
  max-width: var(--max-w);
  margin: 2rem auto;
  padding: 0 var(--pad) 2rem;
  font: 16px/var(--line) var(--sans);
  color: #111;
}

h1 { font-size: 1.5rem; margin: 0 0 1rem; }
h2 { font-size: 1.15rem; margin: 1.5rem 0 0.5rem; }
h3 { font-size: 1rem; margin: 1rem 0 0.5rem; }

p { margin: 0.5rem 0; }

code, pre, .mono, .hex, .addr { font-family: var(--mono); word-break: break-all; }

pre {
  background: var(--bg-soft);
  padding: 0.75rem;
  border-radius: 4px;
  overflow-x: auto;
  margin: 0.5rem 0;
  font-size: 13px;
  line-height: 1.5;
}

.warn {
  border-left: 4px solid var(--warn);
  padding: 0.75rem 1rem;
  background: var(--bg-warn);
  margin: 1rem 0;
}
.warn strong { display: block; margin-bottom: 0.5rem; }
.warn ul { margin: 0.5rem 0 0 1.25rem; padding: 0; }
.warn li { margin: 0.25rem 0; }

.err-msg { color: var(--err); font-size: 0.9rem; margin-top: 0.25rem; }
.err-border { border-color: var(--err) !important; }

input, select, textarea {
  font-family: var(--sans);
  padding: 0.4rem 0.5rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  width: 100%;
  font-size: 1rem;
}
input.mono { font-family: var(--mono); }

button {
  font: inherit;
  padding: 0.4rem 0.8rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
  cursor: pointer;
}
button:hover { background: var(--bg-soft); }
button:active { background: #eee; }

.row { display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; margin: 0.5rem 0; }
.row > label { flex: 0 0 auto; min-width: 8rem; }
.row > input, .row > select { flex: 1 1 auto; min-width: 12rem; }

.nav {
  display: flex;
  gap: 1rem;
  align-items: center;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.5rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}
.nav a { text-decoration: none; color: inherit; }
.nav a:hover { text-decoration: underline; }
.nav .brand { font-weight: 600; }
.nav #lang-toggle {
  margin-left: auto;
  background: none;
  border: 1px solid var(--border);
  padding: 0.25rem 0.6rem;
  cursor: pointer;
  font-size: 0.9rem;
}

.footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.9rem;
}
.footer p { margin: 0.25rem 0; }
.footer a { color: inherit; }

details { margin: 0.5rem 0; }
summary { cursor: pointer; user-select: none; padding: 0.25rem 0; font-weight: 600; }
details[open] summary { margin-bottom: 0.5rem; }

table { border-collapse: collapse; width: 100%; margin: 0.5rem 0; }
th, td { text-align: left; padding: 0.4rem 0.6rem; border-bottom: 1px solid var(--border); }
th { background: var(--bg-soft); font-weight: 600; }
td.num { font-family: var(--mono); }

.tabs { display: flex; gap: 0.5rem; margin: 0.5rem 0; flex-wrap: wrap; }
.tabs label { padding: 0.4rem 0.8rem; border: 1px solid var(--border); border-radius: 4px; cursor: pointer; }
.tabs input[type="radio"] { display: none; }
.tabs input[type="radio"]:checked + label { background: #111; color: #fff; border-color: #111; }

.update-banner {
  position: fixed;
  bottom: 1rem;
  left: 50%;
  transform: translateX(-50%);
  background: #111;
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  display: flex;
  gap: 0.75rem;
  align-items: center;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  z-index: 1000;
}
.update-banner button {
  background: #fff;
  color: #111;
  border-color: #fff;
}

@media (max-width: 480px) {
  body { margin: 1rem auto; }
  .row > label { min-width: 100%; }
}