/* styles-public.css — 公开首页 / 登录 / 帮助页
 * 视觉方向：书籍编辑版式 + 粗线条平涂卡通插画（Editorial / flat cartoon）
 *   纸底 #f7f4ec + 卡面 #fffdf8 + 墨绿主色 #1f6f63 + 陶土点缀 #b4552d（仅插画与否定标记）
 *   显示体用旧式衬线（Iowan Old Style / Palatino / Songti SC），正文用 Avenir Next / PingFang SC，
 *   标签与图表注脚用等宽体 —— 咨询报告式 EXHIBIT 编号 + 书籍式 Fig. 图版编号。
 *   插画全部满幅填充图框；图文并置，避免大面积留白。
 * 约束：全部本地字体栈，零外部 CDN / webfont；图标一律内联 SVG；直角小编辑圆角（2–4px）。
 */

:root {
  --pub-bg: #f7f4ec;
  --pub-bg-deep: #f0ebdd;
  --pub-surface: #fffdf8;
  --pub-ink: #22301f;
  --pub-ink-2: #5c5749;
  --pub-ink-3: #7a7466;
  --pub-accent: #1f6f63;
  --pub-accent-deep: #14544a;
  --pub-accent-soft: #eef5f3;
  --pub-accent-line: #bcd8d1;
  --pub-clay: #b4552d;
  --pub-clay-soft: #f6ebe4;
  --pub-line: #e3ddcd;
  --pub-line-strong: #d9d2c0;
  --pub-serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, "Songti SC", "STSong", serif;
  --pub-sans: "Avenir Next", Avenir, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --pub-mono: "SF Mono", "Iosevka", Menlo, Consolas, "Courier New", monospace;
  --pub-radius-btn: 2px;
  --pub-radius-card: 3px;
  --pub-max: 1180px;
  --pub-grain: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.82' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)' opacity='.05'/%3E%3C/svg%3E");
}

[hidden]:not([hidden="until-found" i]) { display: none !important; }

/* 无障碍：仅供读屏 */
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap; border: 0;
}
#landing :where(a, button, input, summary):focus-visible,
.l-foot :where(a, button):focus-visible {
  outline: 3px solid var(--pub-accent-deep);
  outline-offset: 3px;
}

/* ---------- 顶栏 ---------- */
.l-top {
  position: sticky; top: 0; z-index: 30;
  display: flex; align-items: center; gap: 20px;
  max-width: var(--pub-max); margin: 0 auto; padding: 13px clamp(16px, 4vw, 24px);
  border-bottom: 1px solid transparent;
  background: color-mix(in srgb, var(--pub-bg) 92%, transparent);
  backdrop-filter: saturate(1.1) blur(7px);
}
.l-brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; color: var(--pub-ink); flex: none; }
.l-brand img { display: block; border-radius: 4px; }
.l-name { font-family: var(--pub-serif); font-weight: 600; font-size: 21px; letter-spacing: .16em; }
.l-sub {
  font: 600 10px/1 var(--pub-mono); letter-spacing: .14em; text-transform: uppercase;
  color: var(--pub-ink-3); border-left: 1px solid var(--pub-line-strong); padding-left: 10px;
}
.l-nav { display: flex; align-items: center; gap: 2px; margin-left: auto; flex-wrap: nowrap; overflow-x: auto; scrollbar-width: none; }
.l-nav::-webkit-scrollbar { display: none; }
.l-nav a {
  display: inline-flex; align-items: center; min-height: 38px; padding: 0 11px;
  color: var(--pub-ink-2); text-decoration: none; font-size: 13.5px; letter-spacing: .02em;
  white-space: nowrap; border-radius: var(--pub-radius-btn); border-bottom: 1px solid transparent;
}
.l-nav a:hover { color: var(--pub-accent-deep); border-bottom-color: var(--pub-accent); }
.l-nav .l-btn { margin-left: 10px; border-bottom-width: 1.5px; }
.l-nav .l-btn:hover { border-bottom-color: var(--pub-accent-deep); }
.l-nav [data-return-app] {
  display: inline-flex; min-height: 44px; padding: 0 10px; flex: none;
  border: 1px solid var(--pub-accent-line); background: var(--pub-accent-soft); color: var(--pub-accent-deep); font-weight: 600;
}
.l-nav [data-return-app]:focus-visible { outline: 3px solid var(--pub-accent-deep); outline-offset: 2px; }
.l-lang {
  min-height: 34px; min-width: 40px; margin-left: 8px; padding: 0 9px;
  border: 1px solid var(--pub-line-strong); border-radius: var(--pub-radius-btn);
  background: transparent; color: var(--pub-ink-2); font: 600 11px/1 var(--pub-mono);
  letter-spacing: .12em; text-transform: uppercase; cursor: pointer;
  transition: color .18s ease, border-color .18s ease, background .18s ease;
}
.l-lang:hover { color: var(--pub-accent-deep); border-color: var(--pub-accent); background: var(--pub-accent-soft); }
@media (max-width: 640px) { .l-lang { margin-left: 4px; } }

/* ---------- 按钮 ---------- */
.l-btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 7px;
  min-height: 44px; padding: 0 18px; border-radius: var(--pub-radius-btn);
  border: 1.5px solid var(--pub-ink); background: transparent; color: var(--pub-ink);
  font-family: var(--pub-sans); font-size: 14.5px; font-weight: 600; letter-spacing: .03em;
  text-decoration: none; cursor: pointer;
  transition: background .18s ease, color .18s ease, border-color .18s ease, transform .1s ease;
}
.l-btn:hover { background: var(--pub-ink); color: var(--pub-bg); }
.l-btn:active { transform: translateY(1px); }
.l-btn-primary { background: var(--pub-accent); border-color: var(--pub-accent); color: #fff; }
.l-btn-primary:hover { background: var(--pub-accent-deep); border-color: var(--pub-accent-deep); color: #fff; }
.l-btn-lg { min-height: 50px; padding: 0 26px; font-size: 15.5px; }
.l-linkbtn { border: 0; background: none; padding: 0; color: inherit; font: inherit; cursor: pointer; text-decoration: underline; text-underline-offset: 3px; }
.l-linkbtn:hover { color: var(--pub-accent-deep); }
.l-link {
  color: var(--pub-accent-deep); font: 600 12.5px/1.6 var(--pub-mono); letter-spacing: .04em;
  text-decoration: none; border-bottom: 1px solid var(--pub-accent-line); padding-bottom: 2px;
}
.l-link:hover { border-bottom-color: var(--pub-accent-deep); }

/* 内联图标 */
.l-ic { width: 15px; height: 15px; flex: none; vertical-align: -2px; margin-right: 6px; }

/* ---------- 首页基础 ---------- */
#landing {
  background-color: var(--pub-bg);
  background-image: var(--pub-grain);
  color: var(--pub-ink); min-height: 100vh;
  font-family: var(--pub-sans);
  overflow-x: clip;
}
#landing main { max-width: var(--pub-max); margin: 0 auto; padding: 0 clamp(16px, 4vw, 24px) 0; }
#landing h1, #landing h2, #landing h3 { font-family: var(--pub-serif); font-weight: 600; }

/* ---------- 首屏 ---------- */
.l-hero {
  display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: clamp(24px, 4.5vw, 56px); align-items: center;
  padding: clamp(26px, 5vw, 58px) 0 clamp(20px, 3vw, 30px);
}
.l-hero-copy { position: relative; }
.l-kicker {
  margin: 0 0 18px; font: 600 10.5px/1.5 var(--pub-mono);
  letter-spacing: .2em; text-transform: uppercase; color: var(--pub-accent);
  display: flex; align-items: center; gap: 10px;
}
.l-kicker::after { content: ""; flex: 1 1 auto; height: 1px; background: var(--pub-line-strong); max-width: 120px; }
.l-hero h1 {
  font-size: clamp(40px, 6.4vw, 70px); line-height: 1.1; letter-spacing: .01em;
  margin: 0 0 20px; font-weight: 600; color: var(--pub-ink);
}
.l-lead {
  margin: 0 0 26px; font-size: clamp(14.5px, 1.5vw, 16px); line-height: 1.95;
  color: var(--pub-ink-2); max-width: 34em;
}
.l-lead strong { color: var(--pub-ink); font-weight: 600; }
.l-dropcap {
  float: left; font-family: var(--pub-serif); font-size: 3.5em; line-height: .84;
  font-weight: 600; color: var(--pub-clay); margin: .06em .12em 0 0;
}
.l-cta { display: flex; gap: 12px; flex-wrap: wrap; }
.l-note {
  margin: 18px 0 0; font: 400 11px/1.7 var(--pub-mono); letter-spacing: .04em;
  color: var(--pub-ink-3); text-transform: none;
}

.l-hero-art { margin: 0; position: relative; background: transparent; padding: 0; border: 0; box-shadow: none; }
.l-hero-art img { display: block; width: 100%; height: auto; aspect-ratio: 4 / 3; object-fit: cover; border: 1px solid var(--pub-line-strong); background: var(--pub-surface); }
.l-hero-art figcaption,
.l-illus figcaption {
  margin: 0; padding: 10px 2px 12px;
  font: 400 11px/1.7 var(--pub-mono); letter-spacing: .03em; color: var(--pub-ink-3);
  border-top: 1px solid transparent;
}
.l-hero-art figcaption { border-top: 0; }

/* ---------- 数字条 ---------- */
.l-strip {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 2px solid var(--pub-ink); border-bottom: 1px solid var(--pub-line-strong);
  margin: 6px 0 0; padding: 20px 0 18px;
}
.l-strip div { padding: 0 20px; border-left: 1px solid var(--pub-line-strong); }
.l-strip div:first-child { border-left: 0; padding-left: 0; }
.l-strip b {
  display: block; font-family: var(--pub-serif); font-weight: 600;
  font-size: 27px; line-height: 1.15; letter-spacing: .01em; color: var(--pub-ink);
}
.l-strip span {
  display: block; margin-top: 6px; font: 400 10.5px/1.6 var(--pub-mono);
  letter-spacing: .06em; color: var(--pub-ink-3);
}

/* ---------- 通用 section ---------- */
.l-section { padding: clamp(40px, 6.5vw, 76px) 0 8px; scroll-margin-top: 88px; }
.l-section-head { display: grid; gap: 10px; margin-bottom: 26px; max-width: 62em; }
.l-sec-kicker {
  margin: 0; font: 600 10.5px/1.5 var(--pub-mono);
  letter-spacing: .2em; text-transform: uppercase; color: var(--pub-accent);
}
.l-section-head h2 {
  margin: 0; font-size: clamp(25px, 3.4vw, 36px); line-height: 1.28; letter-spacing: .01em;
}
.l-section-head > p:not(.l-sec-kicker) {
  margin: 0; color: var(--pub-ink-2); font-size: 14.5px; line-height: 1.9; max-width: 46em;
}

/* ---------- EXHIBIT（咨询报告式图表框） ---------- */
.l-exhibit {
  position: relative; margin: 0 0 16px; padding: 0;
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-radius: var(--pub-radius-card);
}
.l-exhibit::before, .l-exhibit::after {
  content: ""; position: absolute; width: 9px; height: 9px; pointer-events: none;
  border-color: var(--pub-accent); border-style: solid;
}
.l-exhibit::before { top: -1px; left: -1px; border-width: 2px 0 0 2px; }
.l-exhibit::after { bottom: -1px; right: -1px; border-width: 0 2px 2px 0; }
.l-exhibit-title {
  margin: 0; padding: 12px 16px 11px;
  border-bottom: 1px solid var(--pub-line);
  font: 600 10.5px/1.4 var(--pub-mono); letter-spacing: .18em; text-transform: uppercase;
  color: var(--pub-ink); background: var(--pub-bg-deep);
}
.l-exhibit .diagram { display: block; width: 100%; height: auto; padding: 14px 12px 10px; }
.l-exhibit > .l-fit-grid { padding: 16px; }
.l-matrix-wrap { margin: 0 0 16px; padding: 12px; overflow-x: auto; }
.l-matrix-wrap .diagram { display: block; width: 100%; min-width: 720px; height: auto; }

/* 图表内文字：默认衬线，带 font-family 属性的标签走等宽 */
.diagram { font-family: var(--pub-serif); }
.diagram text { font-family: var(--pub-serif); }
.diagram [font-family] text, .diagram text[font-family] { font-family: var(--pub-mono); }

/* ---------- 插画图版（Fig.） ---------- */
.l-illus {
  margin: 26px 0 0; background: transparent; padding: 0;
  border: 0; border-radius: 0; box-shadow: none;
}
.l-illus img { display: block; width: 100%; height: auto; border: 1px solid var(--pub-line-strong); background: var(--pub-surface); }
.l-illus figcaption { padding: 11px 2px 12px; }
.l-illus-banner img { aspect-ratio: 16 / 9; object-fit: cover; object-position: center; }
.l-illus-fill img { aspect-ratio: 4 / 3; object-fit: cover; }

/* 图文并置带（避免大图留白） */
.l-band {
  display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: clamp(20px, 3vw, 36px); align-items: center; margin: 26px 0 0;
}
.l-band-art { margin: 0; }
.l-band-art img {
  display: block; width: 100%; aspect-ratio: 4 / 3; object-fit: cover;
  border: 1px solid var(--pub-line-strong); background: var(--pub-surface);
}
.l-band-art figcaption {
  margin: 0; padding: 10px 2px 0;
  font: 400 11px/1.7 var(--pub-mono); letter-spacing: .03em; color: var(--pub-ink-3);
}
.l-band-copy { display: flex; flex-direction: column; gap: 14px; }
.l-tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 4px 0 0; }
.l-tags span {
  font: 600 10.5px/1.9 var(--pub-mono); letter-spacing: .08em; color: var(--pub-accent-deep);
  border: 1px solid var(--pub-accent-line); background: var(--pub-accent-soft);
  padding: 2px 10px; border-radius: 2px;
}
.l-pull {
  margin: 0; font-family: var(--pub-serif); font-size: clamp(19px, 2.2vw, 25px); line-height: 1.62;
  color: var(--pub-ink); border-left: 3px solid var(--pub-clay); padding-left: 18px;
}

/* ---------- 01 理论 ---------- */
.l-theory-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 12px; }
.l-theory-card {
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-top: 2px solid var(--pub-accent); border-radius: var(--pub-radius-card);
  padding: 18px 16px 14px;
}
.l-theory-card h3 { margin: 0 0 12px; font-size: 17px; letter-spacing: .02em; }
.l-theory-card ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.l-theory-card li {
  font-size: 12.5px; line-height: 1.65; color: var(--pub-ink-2);
  padding-left: 12px; position: relative;
}
.l-theory-card li::before {
  content: ""; position: absolute; left: 0; top: .62em; width: 5px; height: 1px; background: var(--pub-accent);
}
.l-theory-card li b { color: var(--pub-ink); font-weight: 600; }
.l-theory-card .l-map {
  margin: 14px 0 0; padding-top: 11px; border-top: 1px dashed var(--pub-line-strong);
  font: 600 10px/1.55 var(--pub-mono); color: var(--pub-accent); letter-spacing: .06em; text-transform: uppercase;
}
.l-footnote {
  margin: 18px 0 0; color: var(--pub-ink-3); line-height: 1.85;
  font: 400 11.5px/1.85 var(--pub-mono); letter-spacing: .01em; max-width: 62em;
}
.l-footnote a { color: var(--pub-accent-deep); }

/* ---------- 02 模型注卡 ---------- */
.l-model-notes { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; margin-top: 4px; }
.l-model-notes article {
  border: 1px solid var(--pub-line-strong); border-left: 3px solid var(--pub-accent);
  border-radius: var(--pub-radius-card); background: var(--pub-surface); padding: 16px 18px;
}
.l-model-notes h3 {
  margin: 0 0 8px; font: 600 10.5px/1.4 var(--pub-mono);
  letter-spacing: .18em; text-transform: uppercase; color: var(--pub-accent);
}
.l-model-notes p { margin: 0; font-size: 13px; line-height: 1.85; color: var(--pub-ink-2); }

/* ---------- 03 适用边界 ---------- */
.l-fit-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.l-fit-card {
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-radius: var(--pub-radius-card); padding: 18px 18px 16px;
}
.l-fit-card h3 {
  margin: 0 0 14px; padding-bottom: 11px; border-bottom: 1px solid var(--pub-line);
  font-family: var(--pub-serif); font-size: 18px; letter-spacing: .02em;
  display: flex; align-items: center;
}
.l-fit-card ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 9px; }
.l-fit-card li {
  position: relative; padding-left: 16px; font-size: 13px; line-height: 1.7; color: var(--pub-ink-2);
}
.l-fit-yes { border-top: 2px solid var(--pub-accent); }
.l-fit-no { border-top: 2px solid var(--pub-clay); background: color-mix(in srgb, var(--pub-clay-soft) 45%, var(--pub-surface)); }
.l-fit-effect { border-top: 2px solid var(--pub-ink-3); }
.l-fit-yes h3 { color: var(--pub-accent-deep); }
.l-fit-no h3 { color: var(--pub-clay); }
.l-fit-effect h3 { color: var(--pub-ink-2); }
.l-fit-yes li::before { content: ""; position: absolute; left: 0; top: .66em; width: 7px; height: 1px; background: var(--pub-accent); }
.l-fit-no li::before { content: ""; position: absolute; left: 0; top: .66em; width: 7px; height: 1px; background: var(--pub-clay); }
.l-fit-effect li::before { content: ""; position: absolute; left: 0; top: .66em; width: 7px; height: 1px; background: var(--pub-ink-3); }
.l-boundary {
  margin: 14px 0 0; padding-top: 11px; border-top: 1px dashed var(--pub-line-strong);
  font: 400 11px/1.75 var(--pub-mono); color: var(--pub-ink-3); letter-spacing: .01em;
}

/* ---------- 04 四步 ---------- */
.l-steps {
  list-style: none; margin: 14px 0 0; padding: 0; counter-reset: step;
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0;
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-radius: var(--pub-radius-card);
}
.l-steps li {
  position: relative; padding: 20px;
  border-left: 1px solid var(--pub-line);
  display: flex; flex-direction: column; gap: 9px; background: transparent;
}
.l-steps li:first-child { border-left: 0; }
.l-step-n {
  font: 600 11px/1 var(--pub-mono); color: var(--pub-clay); letter-spacing: .16em;
  display: flex; align-items: center; gap: 8px;
}
.l-step-n::after { content: ""; flex: 1 1 auto; height: 1px; background: var(--pub-line-strong); max-width: 44px; }
.l-steps h3 { margin: 0; font-size: 18px; letter-spacing: .02em; }
.l-steps p { margin: 0; font-size: 13px; color: var(--pub-ink-2); line-height: 1.85; }

/* ---------- 05 功能 ---------- */
.l-features { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.l-features article {
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-radius: var(--pub-radius-card); padding: 20px 20px 18px; position: relative;
}
.l-features article::before {
  content: ""; position: absolute; top: 0; left: 0; width: 34px; height: 2px; background: var(--pub-accent);
}
.l-features h3 { margin: 6px 0 9px; font-size: 17.5px; letter-spacing: .02em; }
.l-features p { margin: 0; font-size: 13px; color: var(--pub-ink-2); line-height: 1.85; }

/* ---------- 06 证据 ---------- */
.l-evidence {
  display: grid; grid-template-columns: minmax(0, 1.04fr) minmax(0, .96fr);
  grid-template-areas: "copy exhibit" "review review";
  gap: 24px clamp(20px, 3vw, 40px); align-items: start;
  margin: 0; padding: clamp(22px, 3vw, 34px);
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-radius: var(--pub-radius-card);
}
.l-evidence-copy { grid-area: copy; }
.l-evidence .l-exhibit-inline { grid-area: exhibit; margin: 0; }
.l-evidence-review {
  grid-area: review; display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: clamp(20px, 3vw, 36px); align-items: center;
  border-top: 1px solid var(--pub-line); padding-top: 24px;
}
.l-evidence-review .l-illus-fill { margin: 0; box-shadow: none; }
.l-evidence-review .l-pull { font-size: clamp(18px, 2vw, 23px); }
.l-evidence-copy h2 { margin: 0 0 10px; font-size: clamp(22px, 2.6vw, 29px); letter-spacing: .01em; }
.l-evidence-copy > p { margin: 0 0 18px; color: var(--pub-ink-2); font-size: 14px; line-height: 1.9; }
.l-legend { list-style: none; margin: 0 0 20px; padding: 16px 0 0; border-top: 1px solid var(--pub-line); display: grid; gap: 11px; }
.l-legend li { font-size: 13px; color: var(--pub-ink-2); display: flex; align-items: baseline; gap: 10px; line-height: 1.6; }
.l-legend-note { font-size: 12px; color: var(--pub-ink-2); border-left: 3px solid var(--pub-line); padding: 6px 0 6px 12px; margin: 4px 0 0; line-height: 1.6; }

/* 证据等级 chip */
.ev {
  display: inline-block; font: 600 10px/1.8 var(--pub-mono); letter-spacing: .08em;
  padding: 0 7px; border-radius: 2px; border: 1px solid var(--pub-line-strong); flex: none;
}
.ev1 { background: #e3f1ed; color: #1f5a4d; border-color: #b7d9cf; }
.ev2 { background: #e9eef0; color: #2f4a52; border-color: #c6d3d8; }
.ev3 { background: #f4efe2; color: #6b5726; border-color: #dfd2ae; }
.ev4 { background: #f6ebe4; color: #8a3520; border-color: #e8c9ba; }

/* ---------- CTA ---------- */
.l-cta-band {
  display: grid; grid-template-columns: minmax(0, .92fr) minmax(0, 1.08fr);
  gap: 0; align-items: stretch; margin: clamp(40px, 6vw, 72px) 0 0;
  border-top: 3px double var(--pub-ink); border-bottom: 1px solid var(--pub-line-strong);
  background: var(--pub-bg-deep);
}
.l-cta-art { margin: 0; position: relative; overflow: hidden; background: var(--pub-bg-deep); border-right: 1px solid var(--pub-line-strong); }
.l-cta-art img { display: block; width: 100%; height: 100%; min-height: 300px; object-fit: cover; object-position: center 45%; }
.l-cta-copy { padding: clamp(26px, 4vw, 48px) clamp(22px, 3.6vw, 46px); display: flex; flex-direction: column; justify-content: center; gap: 14px; }
.l-cta-copy h2 { margin: 0; font-size: clamp(26px, 3.6vw, 40px); line-height: 1.24; letter-spacing: .01em; }
.l-cta-copy > p:not(.l-sec-kicker) { margin: 0 0 6px; font-size: 14px; line-height: 1.9; color: var(--pub-ink-2); max-width: 34em; }
.l-cta-copy .l-btn { align-self: flex-start; }

/* ---------- 页脚 ---------- */
.l-foot {
  max-width: var(--pub-max); margin: 0 auto; padding: 28px clamp(16px, 4vw, 24px) 44px;
  border-top: 1px solid var(--pub-line-strong);
  display: flex; align-items: center; gap: 18px; flex-wrap: wrap;
  font-size: 13px; color: var(--pub-ink-2);
}
.l-foot-brand {
  display: inline-flex; align-items: center; gap: 9px;
  font-family: var(--pub-serif); font-weight: 600; font-size: 15px; letter-spacing: .1em; color: var(--pub-ink);
}
.l-foot-brand img { border-radius: 3px; }
.l-foot nav { display: flex; gap: 18px; flex-wrap: wrap; align-items: center; }
.l-foot a { color: var(--pub-ink-2); text-decoration: none; border-bottom: 1px solid transparent; }
.l-foot a:hover { color: var(--pub-accent-deep); border-bottom-color: var(--pub-accent-line); }
.l-copy { flex-basis: 100%; margin: 4px 0 0; font: 400 11.5px/1.8 var(--pub-mono); color: var(--pub-ink-3); }

/* ---------- 帮助页 ---------- */
body.pub {
  background-color: var(--pub-bg); background-image: var(--pub-grain);
  color: var(--pub-ink); font-family: var(--pub-sans);
}
body.pub h1, body.pub h2 { font-family: var(--pub-serif); font-weight: 600; }
.help { max-width: 880px; margin: 0 auto; padding: 26px clamp(16px, 4vw, 24px) 44px; }
.help h1 { font-size: clamp(32px, 4.6vw, 46px); margin: 10px 0 12px; letter-spacing: .01em; }
.help-lead { color: var(--pub-ink-2); font-size: 15.5px; line-height: 1.9; margin: 0 0 28px; max-width: 40em; }
.help h2 { font-size: 22px; margin: 34px 0 12px; letter-spacing: .02em; }
.help-hotlines {
  background: var(--pub-surface); border: 1px solid var(--pub-line-strong);
  border-top: 2px solid var(--pub-accent); border-radius: var(--pub-radius-card); padding: 22px 24px;
}
.help-hotlines h2 { margin-top: 0; }
.help-hotlines ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 11px; }
.help-hotlines li { display: grid; grid-template-columns: 170px 1fr; gap: 12px; align-items: baseline; font-size: 14px; }
.help-hotlines b { font-family: var(--pub-serif); font-size: 19px; color: var(--pub-accent-deep); text-decoration: none; letter-spacing: .02em; }
.help-nums { display: flex; align-items: baseline; gap: 8px; }
.help-sep { color: var(--pub-ink-3); font-size: 15px; }
.help-hotlines a { text-decoration: none; }
.help-hotlines a:hover b { text-decoration: underline; }
.help-hotlines span { color: var(--pub-ink-2); }
.help-scene { border-top: 1px solid var(--pub-line); padding-top: 6px; }
.help-scene p { margin: 9px 0; font-size: 14.5px; line-height: 1.9; color: var(--pub-ink-2); }
.help-say {
  border-left: 3px solid var(--pub-accent); background: var(--pub-accent-soft);
  padding: 11px 15px; border-radius: 0 var(--pub-radius-card) var(--pub-radius-card) 0;
  color: var(--pub-ink) !important;
}
.help-scene strong { color: var(--pub-ink); }
.help-faq details { border-top: 1px solid var(--pub-line); padding: 13px 0; }
.help-faq summary { cursor: pointer; font-family: var(--pub-serif); font-weight: 600; font-size: 16.5px; }
.help-faq summary::marker { color: var(--pub-accent); }
.help-faq p { margin: 9px 0 0; color: var(--pub-ink-2); font-size: 14px; line-height: 1.9; }
.help-boundary {
  margin-top: 32px; padding-top: 16px; border-top: 1px solid var(--pub-line-strong);
  font: 400 11.5px/1.85 var(--pub-mono); color: var(--pub-ink-3);
}

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .l-hero { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 28px; }
  .l-band { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 20px; }
}
@media (max-width: 980px) {
  .l-hero { grid-template-columns: minmax(0, 1fr); gap: 22px; padding-top: 18px; }
  .l-hero-copy { order: 0; }
  .l-hero-art { order: 1; margin: 0; }
  .l-hero-art img { aspect-ratio: auto; height: auto; object-fit: contain; }
  .l-steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .l-steps li:nth-child(odd) { border-left: 0; }
  .l-steps li:nth-child(n+3) { border-top: 1px solid var(--pub-line); }
  .l-features { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .l-theory-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .l-fit-grid { grid-template-columns: minmax(0, 1fr); }
  .l-model-notes { grid-template-columns: minmax(0, 1fr); }
  .l-evidence { grid-template-columns: minmax(0, 1fr); grid-template-areas: "copy" "exhibit" "review"; }
  .l-evidence-review { grid-template-columns: minmax(0, 1fr); }
  .l-cta-band { grid-template-columns: minmax(0, 1fr); }
  .l-cta-art img { min-height: 200px; max-height: 260px; }
  .l-band { grid-template-columns: minmax(0, 1fr); }
  .l-strip { grid-template-columns: repeat(2, minmax(0, 1fr)); row-gap: 18px; }
  .l-strip div:nth-child(3) { border-left: 0; padding-left: 0; }
}
@media (max-width: 640px) {
  .l-top { padding: 10px 14px; gap: 8px; flex-wrap: wrap; }
  .l-sub { display: none; }
  .l-nav { min-width: 0; overflow: visible; flex-wrap: wrap; justify-content: flex-end; }
  .l-nav a:not(.l-btn):not([data-return-app]) { display: none; }
  .l-nav .l-btn { margin-left: 0; }
  .l-nav [data-return-app] { padding-inline: 8px; font-size: 13px; }
  .l-lang { min-height: 44px; }
  .l-hero { gap: 18px; }
  .l-kicker { margin-bottom: 12px; letter-spacing: .1em; }
  .l-hero h1 { margin-bottom: 14px; }
  .l-lead { margin-bottom: 18px; line-height: 1.8; }
  .l-steps, .l-features, .l-theory-grid { grid-template-columns: minmax(0, 1fr); }
  .l-steps li { border-left: 0 !important; border-top: 1px solid var(--pub-line); padding: 16px; }
  .l-steps li:first-child { border-top: 0; }
  .l-hero h1 { font-size: clamp(36px, 11.5vw, 48px); }
  .l-dropcap { font-size: 3em; }
  .l-cta .l-btn { flex: 1 1 auto; }
  .l-strip b { font-size: 23px; }
  .l-strip div { padding: 0 14px; }
  .l-exhibit .diagram { padding: 10px 4px 6px; }
  .l-illus-banner img { aspect-ratio: 16 / 9; }
  .help-hotlines li { grid-template-columns: 1fr; gap: 2px; }
  .l-foot { flex-direction: column; align-items: flex-start; gap: 12px; }
}
@media (pointer: coarse) {
  .l-nav a, .l-lang, .l-linkbtn, .help-faq summary { min-block-size: 44px; }
  .l-linkbtn { display: inline-flex; align-items: center; }
}
@media (forced-colors: active) {
  #landing :where(a, button, input, summary):focus-visible,
  .l-foot :where(a, button):focus-visible {
    outline-color: Highlight;
  }
}
@media (prefers-reduced-motion: reduce) {
  .l-btn { transition: none; }
}
@media print {
  .l-top, .l-cta-band { display: none !important; }
  #landing { background-image: none; }
}