/* ==========================================================================
   Vallotton 文档 — 视觉系统

   和应用同一套语言：冰蓝的底、一种钴蓝作强调、细线而不是方框。文章放在一张
   白纸上，左边是整站的目录；标题用衬线（Cormorant Garamond / 思源宋体），
   正文用 Inter 与思源黑体。浅色为底，深色随系统或 data-theme 切换；每一种
   颜色都走变量。
   ========================================================================== */

:root {
  --bg:        #e9edf5;      /* the ground behind the page */
  --paper:     #ffffff;      /* the page itself */
  --card:      #f4f6fb;      /* a block on the page */
  --ink:       #1b2130;
  --ink-2:     #434b5e;
  --ink-3:     #6b7489;
  --accent:    #4166b8;
  --accent-deep: #2a4380;
  --tint:      #ccd6ec;
  --tint-soft: #e4e9f5;
  --rule:      #d6dce9;
  --rule-strong: #b8c3da;
  --brass:     #b08d57;
  --brass-deep: #74644c;
  --ok:        #2e6b3a;
  --danger:    #9f4a3c;
  --code-bg:   #eceff6;      /* inline code */
  --pre-bg:    #1c2230;      /* code blocks, dark on purpose */
  --pre-ink:   #dfe5f2;
  --pre-dim:   #8a94ab;
  --pre-accent:#9fb6ee;
  --shadow:    0 1px 2px rgba(27, 33, 48, 0.06), 0 12px 32px -16px rgba(27, 33, 48, 0.25);

  --font-sans: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-display: "Cormorant Garamond", "Noto Serif SC", "Songti SC", "STSong", Georgia, serif;
  --font-mono: "JetBrains Mono", "SF Mono", Consolas, "Noto Sans SC", "Microsoft YaHei", monospace;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:        #10141c;
    --paper:     #171c27;
    --card:      #1e2432;
    --ink:       #e8ecf5;
    --ink-2:     #b9c1d2;
    --ink-3:     #8f99ae;
    --accent:    #7f9ee3;
    --accent-deep: #b4c6f2;
    --tint:      #2b3752;
    --tint-soft: #222a3b;
    --rule:      #2a3243;
    --rule-strong: #3d4860;
    --brass:     #c9a66b;
    --brass-deep: #d9bf8f;
    --ok:        #7fc38f;
    --danger:    #e08b7c;
    --code-bg:   #252c3b;
    --pre-bg:    #0e1219;
    --pre-ink:   #dfe5f2;
    --pre-dim:   #7f8aa3;
    --pre-accent:#9fb6ee;
    --shadow:    0 1px 2px rgba(0, 0, 0, 0.5), 0 12px 32px -16px rgba(0, 0, 0, 0.8);
  }
}
:root[data-theme="dark"] {
  --bg:        #10141c;
  --paper:     #171c27;
  --card:      #1e2432;
  --ink:       #e8ecf5;
  --ink-2:     #b9c1d2;
  --ink-3:     #8f99ae;
  --accent:    #7f9ee3;
  --accent-deep: #b4c6f2;
  --tint:      #2b3752;
  --tint-soft: #222a3b;
  --rule:      #2a3243;
  --rule-strong: #3d4860;
  --brass:     #c9a66b;
  --brass-deep: #d9bf8f;
  --ok:        #7fc38f;
  --danger:    #e08b7c;
  --code-bg:   #252c3b;
  --pre-bg:    #0e1219;
  --pre-ink:   #dfe5f2;
  --pre-dim:   #7f8aa3;
  --pre-accent:#9fb6ee;
  --shadow:    0 1px 2px rgba(0, 0, 0, 0.5), 0 12px 32px -16px rgba(0, 0, 0, 0.8);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.8;
  font-feature-settings: "liga", "kern";
  text-rendering: optimizeLegibility;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

/* scrollbars: thin, in the page's own colours, no default chrome. The
   standard properties cover Chrome and Firefox; the -webkit- rules cover
   Safari and older engines. */
* { scrollbar-width: thin; scrollbar-color: var(--rule-strong) transparent; }
*:hover { scrollbar-color: var(--accent) transparent; }
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background-color: var(--rule-strong); border-radius: 8px; border: 3px solid transparent; background-clip: padding-box; }
::-webkit-scrollbar-thumb:hover { background-color: var(--accent); }
::-webkit-scrollbar-corner { background: transparent; }
pre, .term { scrollbar-color: var(--pre-dim) transparent; }
pre::-webkit-scrollbar-thumb, .term::-webkit-scrollbar-thumb { background-color: var(--pre-dim); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------------------------------------------------------------- header */
.top {
  position: sticky; top: 0; z-index: 20;
  background: var(--paper);
  border-bottom: 1px solid var(--rule);
}
.top-inner {
  max-width: 1200px; margin: 0 auto; padding: 10px 24px;
  display: flex; align-items: center; gap: 14px;
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); }
.brand:hover { text-decoration: none; }
.brand img { width: 32px; height: 32px; border-radius: 50%; }
.brand .word { font-family: var(--font-display); font-weight: 600; font-size: 22px; letter-spacing: .02em; }
.brand .sub { color: var(--ink-3); font-size: 12px; letter-spacing: .1em; margin-left: 6px; padding-left: 10px; border-left: 1px solid var(--rule); }
nav.menu { margin-left: auto; display: flex; gap: 2px; flex-wrap: wrap; }
nav.menu a {
  color: var(--ink-2); font-size: 14px; padding: 6px 12px; border-radius: 4px;
}
nav.menu a:hover { background: var(--tint-soft); text-decoration: none; }
nav.menu a.active { color: var(--accent-deep); background: var(--tint-soft); font-weight: 500; }
/* the other language: a switch rather than a page, so it stands a little apart */
nav.menu a.lang { margin-left: 10px; padding: 5px 11px; border: 1px solid var(--rule); color: var(--ink-3); font-size: 13px; }
nav.menu a.lang:hover { color: var(--accent-deep); border-color: var(--rule-strong); }

/* ---------------------------------------------------------------- page grid */
.page {
  max-width: 1200px; margin: 0 auto; padding: 28px 24px 72px;
  display: grid; grid-template-columns: 232px minmax(0, 1fr); gap: 32px;
}
.page.single { grid-template-columns: minmax(0, 1fr); }

/* the site's table of contents, down the left */
aside.toc { align-self: start; font-size: 13.5px; }
aside.toc .toc-fixed { position: fixed; top: 78px; width: 232px; max-height: calc(100vh - 96px); display: flex; flex-direction: column; }
aside.toc .toc-title { color: var(--ink-3); letter-spacing: .14em; font-size: 11px; text-transform: uppercase; margin: 14px 0 6px 12px; }
aside.toc .toc-site .toc-title:first-child { margin-top: 0; }
aside.toc a { display: block; color: var(--ink-2); padding: 4px 12px; border-radius: 4px; line-height: 1.5; }
aside.toc a:hover { color: var(--accent-deep); background: var(--tint-soft); text-decoration: none; }
aside.toc a.page-link { font-weight: 500; }
aside.toc a.page-link.current { color: var(--accent-deep); background: var(--tint-soft); }
aside.toc a.l2 { padding-left: 24px; font-size: 12.5px; color: var(--ink-3); }
/* the site index stays put; only the list of this page's sections scrolls */
aside.toc .toc-site { flex: none; }
aside.toc .toc-page { flex: 1 1 auto; min-height: 0; overflow-y: auto; overscroll-behavior: contain; position: relative; padding-bottom: 6px; }
/* a small triangle beside the section being read */
aside.toc .toc-page a { position: relative; }
aside.toc .toc-page a.now { color: var(--ink); }
aside.toc .toc-page a.now::before {
  content: ""; position: absolute; left: 3px; top: 50%; margin-top: -4px;
  border: 4px solid transparent; border-right: 0; border-left: 5px solid var(--accent);
}
aside.toc .toc-page a.l2.now::before { left: 14px; }

/* the page itself */
article {
  background: var(--paper); border: 1px solid var(--rule); border-radius: 10px;
  padding: 44px 56px 56px; min-width: 0; box-shadow: var(--shadow);
}
.page.single article { padding: 40px 56px 56px; }

@media (max-width: 960px) {
  .page { grid-template-columns: minmax(0, 1fr); gap: 16px; padding: 16px 12px 48px; }
  aside.toc { background: var(--paper); border: 1px solid var(--rule); border-radius: 10px; padding: 12px 8px; }
  aside.toc .toc-fixed { position: static; width: auto; max-height: none; }
  aside.toc a.l2 { display: none; }
  aside.toc .toc-page { overflow: visible; }
  article { padding: 24px 20px 32px; border-radius: 8px; }
  .page.single article { padding: 24px 20px 32px; }
}

/* ---------------------------------------------------------------- type */
h1 {
  font-family: var(--font-display); font-weight: 600; font-size: 38px; line-height: 1.25;
  letter-spacing: .01em; margin: 0 0 22px; color: var(--ink); text-wrap: balance;
}
/* the opening paragraph is a paragraph, not a subtitle */
.lede { margin: 0 0 1.1em; }
h2 {
  font-family: var(--font-display); font-weight: 600; font-size: 25px; line-height: 1.3;
  margin: 48px 0 14px; padding-top: 16px; color: var(--ink); position: relative;
}
h2::before { content: ""; position: absolute; top: 0; left: 0; width: 36px; height: 3px; background: var(--accent); border-radius: 2px; }
h2:first-of-type { margin-top: 32px; }
h3 { font-size: 17px; font-weight: 600; margin: 30px 0 10px; color: var(--accent-deep); }
h2, h3 { scroll-margin-top: 76px; }
h4 { font-size: 15px; font-weight: 600; margin: 20px 0 6px; color: var(--ink-2); }
p { margin: 0 0 1.1em; }
article > p, article li { max-width: 74ch; }
ul, ol { padding-left: 1.5em; margin: 0 0 1.1em; }
li { margin: .35em 0; }
li > ul { margin: .3em 0 0; }
strong, b { font-weight: 600; }
small, .muted { color: var(--ink-3); }
hr { border: 0; border-top: 1px solid var(--rule); margin: 32px 0; }
kbd {
  font-family: var(--font-mono); font-size: .85em; padding: 1px 6px;
  border: 1px solid var(--rule-strong); border-bottom-width: 2px; border-radius: 4px; background: var(--card);
}
code {
  font-family: var(--font-mono); font-size: .88em; background: var(--code-bg);
  padding: .12em .4em; border-radius: 4px; color: var(--accent-deep);
}
pre {
  font-family: var(--font-mono); font-size: 13px; line-height: 1.7;
  background: var(--pre-bg); color: var(--pre-ink); padding: 16px 18px; border-radius: 8px;
  overflow-x: auto; margin: 6px 0 20px;
}
pre code { background: none; padding: 0; font-size: inherit; color: inherit; }
pre .c { color: var(--pre-dim); }
pre .k { color: var(--pre-accent); }
pre .ok { color: var(--ok); }

/* ---------------------------------------------------------------- blocks */
.note, .warn, .tip {
  border-left: 3px solid var(--accent); background: var(--card);
  padding: 12px 18px; margin: 18px 0 20px; border-radius: 0 8px 8px 0; max-width: 74ch;
}
.note > :first-child, .warn > :first-child, .tip > :first-child { margin-top: 0; }
.note > :last-child, .warn > :last-child, .tip > :last-child { margin-bottom: 0; }
.warn { border-left-color: var(--brass); }
.tip { border-left-color: var(--ok); }
.label { display: inline-block; font-size: 11px; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 4px; }

.wrap { overflow-x: auto; margin: 6px 0 22px; border: 1px solid var(--rule); border-radius: 8px; }
table { border-collapse: collapse; width: 100%; font-size: 14px; line-height: 1.65; }
th, td { padding: 10px 14px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--rule); }
thead th, tr:first-child th { background: var(--card); color: var(--ink-2); font-weight: 600; font-size: 13px; letter-spacing: .03em; white-space: nowrap; }
tr:last-child td { border-bottom: 0; }
td:first-child { font-weight: 500; }
td code { white-space: nowrap; }
td.req::after { content: "必填"; color: var(--brass-deep); font-size: 11px; margin-left: 6px; letter-spacing: .06em; }
.num { font-variant-numeric: tabular-nums; }
/* the first column names the row: a quarter of the table by default, so labels rarely wrap.
   A table can set its own: <table style="--first-col: 6em">, or auto for just as wide as the labels. */
th:first-child, td:first-child { width: var(--first-col, 26%); min-width: var(--first-col, 9em); }
.group td { background: var(--tint-soft); color: var(--accent-deep); font-weight: 600; font-size: 13px; letter-spacing: .06em; }

sup.fn { font-size: .7em; line-height: 0; vertical-align: super; margin-left: 2px; }
sup.fn a { color: var(--accent); text-decoration: none; }
.footnotes { margin: 40px 0 0; padding-top: 14px; border-top: 1px solid var(--rule); font-size: 13.5px; color: var(--ink-2); }
.footnotes p { max-width: 80ch; }
.footnotes sup { margin-right: 4px; }
:target { scroll-margin-top: 76px; }

dl.terms { margin: 10px 0 1.1em; }
dl.terms dt { font-weight: 600; margin-top: 16px; color: var(--ink); }
dl.terms dt .en { color: var(--ink-3); font-weight: 400; font-size: 13px; margin-left: 8px; font-family: var(--font-mono); }
dl.terms dd { margin: 4px 0 0 0; color: var(--ink-2); max-width: 74ch; }

/* steps: a real sequence, numbered */
ol.steps { list-style: none; padding: 0; counter-reset: step; margin: 16px 0; }
ol.steps > li { counter-increment: step; position: relative; padding-left: 48px; margin: 22px 0; max-width: none; }
ol.steps > li::before {
  content: counter(step); position: absolute; left: 0; top: 2px;
  width: 32px; height: 32px; border-radius: 50%; background: var(--accent); color: #fff;
  font-family: var(--font-display); font-weight: 700; font-size: 17px;
  display: flex; align-items: center; justify-content: center;
}
ol.steps > li > b:first-child { display: block; font-size: 16px; margin-bottom: 6px; }

/* ---------------------------------------------------------------- home */
/* The band at the top of the front page sits on the page's own ground. On a
   dark ground the picture's edges melt into it; on a light ground a dark
   picture fading out reads as a smudge, so there it is a framed picture
   like every other one on the site. The left column is scaled to fill the
   picture's height. */
.hero { background: var(--bg); color: var(--ink); }
.hero-inner { max-width: 1200px; margin: 0 auto; padding: 36px 24px 44px; display: grid; grid-template-columns: minmax(0, 1fr) 520px; gap: 48px; align-items: stretch; }
.hero-text { display: flex; flex-direction: column; justify-content: center; min-height: 760px; padding: 0; }
.hero-title { display: flex; align-items: center; gap: 22px; margin-bottom: 26px; }
.hero-logo { width: 112px; height: 112px; border-radius: 50%; display: block; flex: none; }
.hero-words { display: flex; flex-direction: column; }
.hero h1 { font-size: 84px; margin: 0; color: var(--ink); line-height: 1.05; }
.hero .tag { color: var(--ink-3); letter-spacing: .2em; font-size: 14px; text-transform: uppercase; margin: 6px 0 0 4px; }
.hero p { font-size: 18px; color: var(--ink-2); max-width: 54ch; margin: 0; line-height: 1.85; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 36px; }
.hero .btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 24px; border-radius: 7px; background: var(--accent); color: #fff; font-weight: 600; font-size: 15.5px; border: 1px solid transparent; }
.hero .btn:hover { text-decoration: none; filter: brightness(1.08); }
.hero .btn svg { width: 18px; height: 18px; display: block; }
.hero .btn.ghost { background: transparent; color: var(--ink); border-color: var(--rule-strong); }
.hero .btn.ghost:hover { border-color: var(--ink-3); }
.hero-art { position: relative; width: 520px; height: 760px; justify-self: end; }
.hero-art img { width: 100%; height: 100%; object-fit: cover; object-position: center top; display: block; border-radius: 12px; border: 1px solid var(--rule); box-shadow: var(--shadow); }
.hero-art::after { content: ""; position: absolute; inset: 0; pointer-events: none; display: none;
  background:
    linear-gradient(90deg, var(--bg) 0%, transparent 30%),
    linear-gradient(270deg, var(--bg) 0%, transparent 18%),
    linear-gradient(180deg, var(--bg) 0%, transparent 16%),
    linear-gradient(0deg, var(--bg) 0%, transparent 22%); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .hero-art img { border-radius: 0; border: 0; box-shadow: none; }
  :root:not([data-theme="light"]) .hero-art::after { display: block; }
}
:root[data-theme="dark"] .hero-art img { border-radius: 0; border: 0; box-shadow: none; }
:root[data-theme="dark"] .hero-art::after { display: block; }
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; gap: 8px; padding: 28px 24px 36px; }
  .hero-text { min-height: 0; padding: 0 0 20px; }
  .hero-title { gap: 14px; margin-bottom: 18px; }
  .hero-logo { width: 76px; height: 76px; }
  .hero h1 { font-size: 54px; }
  .hero-art { width: 100%; max-width: 480px; height: 560px; justify-self: center; }
}
@media (max-width: 640px) {
  .hero h1 { font-size: 38px; }
  h1 { font-size: 30px; }
}
.cards { display: grid; grid-template-columns: 1fr; gap: 10px; margin: 14px 0 8px; max-width: 74ch; }
.card {
  display: grid; grid-template-columns: 40px minmax(0, 1fr); column-gap: 14px; row-gap: 2px; align-items: baseline;
  background: var(--card); border: 1px solid var(--rule); border-radius: 8px;
  padding: 14px 18px 13px; color: var(--ink); transition: border-color .15s ease, transform .15s ease;
}
.card:hover { border-color: var(--accent); text-decoration: none; transform: translateY(-1px); }
.card .n { grid-row: 1 / span 2; font-family: var(--font-display); font-size: 15px; letter-spacing: .14em; color: var(--brass-deep); }
.card h3 { margin: 0; font-family: var(--font-display); font-size: 21px; font-weight: 600; color: var(--ink); }
.card p { color: var(--ink-2); font-size: 14px; margin: 0; }
/* the things to prepare: one row each, label on the left */
.facts { margin: 12px 0 28px; max-width: 74ch; border-top: 1px solid var(--rule); }
.facts div { display: grid; grid-template-columns: 112px minmax(0, 1fr); column-gap: 18px; padding: 11px 0; border-bottom: 1px solid var(--rule); font-size: 15px; color: var(--ink-2); line-height: 1.7; }
.facts b { color: var(--ink); font-weight: 600; font-size: 15px; }
@media (max-width: 640px) { .facts div { grid-template-columns: 1fr; row-gap: 2px; } }

figure { margin: 10px 0 24px; }
figure svg { width: 100%; height: auto; display: block; }
figure img.shot { width: 100%; height: auto; display: block; border: 1px solid var(--rule); border-radius: 8px; box-shadow: var(--shadow); background: var(--card); }
figure img.shot.narrow { max-width: 440px; }
.shots-row { display: flex; gap: 16px; flex-wrap: wrap; align-items: flex-start; }
.shots-row img.shot { flex: 1 1 260px; max-width: 360px; }
figcaption { color: var(--ink-3); font-size: 13.5px; margin-top: 8px; line-height: 1.6; }
.svg-text { font-family: var(--font-sans); font-size: 13px; fill: var(--ink); }
.svg-small { font-family: var(--font-sans); font-size: 11.5px; fill: var(--ink-3); }
.svg-box { fill: var(--card); stroke: var(--rule-strong); stroke-width: 1; }
.svg-box-accent { fill: var(--tint-soft); stroke: var(--accent); stroke-width: 1; }
.svg-line { stroke: var(--ink-3); stroke-width: 1.2; fill: none; }
.svg-line-accent { stroke: var(--accent); stroke-width: 1.4; fill: none; }

/* a terminal transcript */
.term {
  background: var(--pre-bg); color: var(--pre-ink); border-radius: 8px;
  padding: 16px 18px; font-family: var(--font-mono); font-size: 12.5px; line-height: 1.65;
  overflow-x: auto; margin: 6px 0 20px; white-space: pre;
}
.term .ok { color: #7fc38f; } .term .dim { color: var(--pre-dim); } .term .blue { color: var(--pre-accent); font-weight: 600; } .term .brass { color: #c9a66b; }

footer.foot {
  color: var(--ink-3); font-size: 13px;
  max-width: 1200px; margin: 0 auto; padding: 8px 24px 40px; display: flex; gap: 18px; flex-wrap: wrap;
}
@media (min-width: 961px) { footer.foot { padding-left: 288px; } }
footer.foot a { color: var(--ink-2); }
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 48px; padding-top: 18px; border-top: 1px solid var(--rule); font-size: 14px; }
.pager a { color: var(--accent-deep); font-weight: 500; }

@media (prefers-reduced-motion: reduce) { .card { transition: none; } }
@media print { .top, aside.toc, .pager, footer.foot { display: none; } .page { display: block; } article { border: 0; box-shadow: none; padding: 0; } }