/* Direction: a well-made technical brief, not a startup landing page. White paper, ink text, one deep green,
   hairline-ruled rows instead of cards. Latin: IBM Plex Sans (self-hosted). Chinese: the reader's system face. */
@font-face { font-family: 'Plex'; src: url('fonts/plex-400.woff2') format('woff2'); font-weight: 400; font-display: swap; unicode-range: U+0000-00FF, U+2010-2027, U+20AC; }
@font-face { font-family: 'Plex'; src: url('fonts/plex-600.woff2') format('woff2'); font-weight: 600; font-display: swap; unicode-range: U+0000-00FF, U+2010-2027, U+20AC; }

:root {
  --paper: #FBFAF7;
  --ink: #15191E;
  --ink-2: #4A5258;
  --line: #DCDAD3;
  --green: #0E5A4E;
  --green-2: #0A463D;
  --tint: #EEF3F0;
  --sans: 'Plex', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Noto Sans CJK SC', 'Noto Sans SC', system-ui, sans-serif;
  --gutter: clamp(20px, 5vw, 64px);
  --col: 1080px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 400 17px/1.6 var(--sans); }
:lang(zh-CN) body, body:lang(zh-CN) { line-height: 1.75; }
::selection { background: var(--green); color: var(--paper); }
a { color: var(--green); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--green-2); }
a:focus-visible, .btn:focus-visible { outline: 2px solid var(--green); outline-offset: 3px; border-radius: 2px; }

.top { max-width: calc(var(--col) + 2 * var(--gutter)); margin: 0 auto; padding: 22px var(--gutter); display: flex; align-items: center; gap: 28px; border-bottom: 1px solid var(--line); }
.brand { font-weight: 600; font-size: 18px; color: var(--ink); text-decoration: none; margin-inline-end: auto; letter-spacing: 0.01em; }
.brand-en { font-weight: 400; color: var(--ink-2); margin-inline-start: 8px; font-size: 15px; }
.top nav { display: flex; gap: 22px; }
.top nav a, .lang { color: var(--ink-2); text-decoration: none; font-size: 15px; }
.top nav a:hover, .lang:hover { color: var(--ink); }
.top nav a[aria-current="page"] { color: var(--ink); text-decoration: underline; text-decoration-color: var(--green); text-underline-offset: 6px; }
.lang { padding: 4px 10px; border: 1px solid var(--line); border-radius: 3px; }

main { max-width: calc(var(--col) + 2 * var(--gutter)); margin: 0 auto; padding: 0 var(--gutter); }
section { padding: 56px 0; border-bottom: 1px solid var(--line); }
section:last-child { border-bottom: 0; }
.hero { padding: 88px 0 72px; }
.hero.small { padding: 64px 0 48px; }
h1 { font-weight: 600; font-size: clamp(30px, 3.6vw, 46px); line-height: 1.15; letter-spacing: -0.01em; margin: 0; max-width: 22em; text-wrap: balance; }
h1:lang(zh-CN) { letter-spacing: 0; line-height: 1.3; max-width: 20em; }
.hero.small h1 { font-size: clamp(28px, 3vw, 38px); }
h2 { font-weight: 600; font-size: 22px; line-height: 1.3; margin: 0 0 22px; }
.lead { margin: 22px 0 0; max-width: 40em; font-size: 19px; color: var(--ink-2); }
.wide { margin: 0; max-width: 46em; }
.actions { margin: 32px 0 0; display: flex; flex-wrap: wrap; align-items: center; gap: 14px 28px; }
.btn { display: inline-block; background: var(--green); color: var(--paper); text-decoration: none; padding: 12px 22px; border-radius: 3px; font-weight: 600; font-size: 16px; transition: background-color 150ms; }
.btn:hover { background: var(--green-2); color: var(--paper); }
.quiet { font-size: 16px; }

.rows { margin: 0; display: grid; grid-template-columns: minmax(180px, 280px) 1fr; }
.rows dt, .rows dd { margin: 0; padding: 18px 0; border-top: 1px solid var(--line); }
.rows dt { font-weight: 600; padding-inline-end: 24px; }
.rows dd { color: var(--ink-2); max-width: 44em; }
.rows dt:first-of-type, .rows dt:first-of-type + dd { border-top: 0; padding-top: 0; }

.tw { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; min-width: 560px; font-size: 16px; }
th, td { text-align: start; vertical-align: top; padding: 14px 18px 14px 0; border-top: 1px solid var(--line); }
thead th { border-top: 0; font-weight: 600; color: var(--ink-2); font-size: 14px; }
tbody th { font-weight: 600; width: 26%; }
tbody td:last-child { color: var(--green-2); }

.flow { margin: 0; padding: 0; list-style: none; max-width: 46em; }
.flow li { padding: 14px 0; border-top: 1px solid var(--line); color: var(--ink-2); }
.flow li:first-child { border-top: 0; padding-top: 0; }
.flow b { color: var(--ink); font-weight: 600; margin-inline-end: 6px; }

.next { background: var(--tint); margin: 24px calc(-1 * var(--gutter)) 0; padding: 56px var(--gutter); border-bottom: 0; border-radius: 4px; }

footer { max-width: calc(var(--col) + 2 * var(--gutter)); margin: 32px auto 0; padding: 28px var(--gutter) 40px; border-top: 1px solid var(--line); color: var(--ink-2); font-size: 15px; }
footer p { margin: 0 0 6px; display: flex; flex-wrap: wrap; gap: 6px 18px; }
footer .fine { font-size: 13px; }

@media (max-width: 720px) {
  body { font-size: 16px; }
  .top { flex-wrap: wrap; gap: 12px 18px; padding-top: 16px; padding-bottom: 16px; }
  .brand { width: 100%; }
  .top nav { gap: 16px; flex-wrap: wrap; }
  .hero { padding: 48px 0 40px; }
  .hero.small { padding: 40px 0 32px; }
  section { padding: 40px 0; }
  .lead { font-size: 17px; }
  .rows { grid-template-columns: 1fr; }
  .rows dt { padding-bottom: 4px; }
  .rows dd { border-top: 0; padding-top: 0; }
  .next { margin-inline: calc(-1 * var(--gutter)); border-radius: 0; }
}
@media (prefers-reduced-motion: reduce) { .btn { transition: none; } }