/* Colors copied from the app (LYUserContentView / LYBrandSlogan). */
:root {
  --ink: #171717;
  --gray: #777777;
  --light: #9b9b9b;
  --red: #f03333;
  --button: #e32d2d;
  --plate: #f2f2f2;
  --rule: rgba(224, 224, 224, 0.7);
  --font: "PingFang SC", -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; }
body { background: #fff; color: var(--ink); font-family: var(--font); line-height: 1.6; }
a { color: inherit; text-decoration: none; }
a:focus-visible { outline: 2px solid var(--red); outline-offset: 3px; border-radius: 8px; }

.nav, main, .foot { max-width: 1152px; margin: 0 auto; padding: 0 24px; }

/* Nav */
.nav { display: flex; align-items: center; justify-content: space-between; gap: 16px; height: 88px; }
.brand { display: flex; align-items: center; gap: 6px; }
.brand-text { display: flex; flex-direction: column; align-items: center; line-height: 1.15; }
.brand-text b { font-size: 24px; font-weight: 600; }
.brand-text small { font-size: 12px; font-weight: 600; color: var(--light); letter-spacing: 0.02em; }
.links { display: flex; gap: 4px; }
.links a { padding: 8px 16px; border-radius: 13px; font-size: 15px; color: var(--gray); transition: background .15s, color .15s; }
.links a:hover { background: var(--plate); color: var(--ink); }
.links a[aria-current="page"] { background: var(--plate); color: var(--ink); font-weight: 600; }

/* Hero: same grey plate, staggered slogan, waveform, red pill as the app's home */
.hero {
  display: grid; grid-template-columns: auto 1fr; grid-template-rows: auto auto;
  align-items: center; column-gap: 48px; row-gap: 28px;
  background: var(--plate); border-radius: 26px; padding: 56px 48px 44px 56px;
}
.slogan { font-weight: 600; font-size: 36px; line-height: 1.3; }
.slogan .line { display: block; white-space: nowrap; }
.slogan .second { padding-left: 82px; margin-top: 8px; }
.slogan em { font-style: normal; color: var(--red); font-size: 48px; margin-right: 12px; }
.wave { width: 100%; height: auto; max-width: 640px; justify-self: end; }
.lead { font-size: 15px; color: var(--gray); }
.cta {
  justify-self: end; display: inline-flex; align-items: center; gap: 10px;
  height: 50px; padding: 0 28px; border-radius: 999px;
  background: var(--button); color: #fff; font-size: 20px; font-weight: 600; transition: filter .15s;
}
.cta:hover { filter: brightness(0.94); }
.cta:active { filter: brightness(0.86); }
.cta svg { width: 24px; height: 24px; fill: none; stroke: currentColor; stroke-width: 2.2; stroke-linecap: round; }

/* Sections */
.block { margin-top: 64px; }
.bar { position: relative; padding-left: 13px; font-size: 20px; font-weight: 600; margin-bottom: 8px; }
.bar::before { content: ""; position: absolute; left: 0; top: 0.3em; bottom: 0.3em; width: 3px; border-radius: 2px; background: var(--red); }

.rows { list-style: none; }
.rows li { display: flex; align-items: center; gap: 28px; padding: 24px 4px; border-bottom: 1px solid var(--rule); }
.rows li > div { flex: 1; }
.pic { width: 400px; max-width: 45%; height: auto; flex-shrink: 0; }
.rows li:last-child { border-bottom: 0; }
.num { color: var(--red); font-size: 32px; font-weight: 600; line-height: 1; min-width: 44px; font-variant-numeric: tabular-nums; }
.rows h3 { font-size: 18px; font-weight: 600; }
.rows p { color: var(--gray); font-size: 15px; }

.plate { background: var(--plate); border-radius: 16px; padding: 28px 32px; margin-top: 12px; }
.plate h3 { font-size: 18px; font-weight: 600; margin-bottom: 6px; }
.plate p { color: #444; font-size: 15px; max-width: 46em; }
.more { display: inline-block; margin-top: 12px; color: var(--gray); font-size: 14px; }
.more:hover { color: var(--ink); }

/* Footer: grey plate like the hero, three link columns */
.foot { margin-top: 80px; margin-bottom: 24px; }
.foot-top, .foot-bottom { background: var(--plate); }
.foot-top {
  display: flex; justify-content: space-between; gap: 48px;
  border-radius: 26px 26px 0 0; padding: 44px 56px 36px;
}
.foot-about { max-width: 420px; }
.foot-about p { margin-top: 18px; font-size: 14px; color: var(--gray); }
.foot-cols { display: flex; gap: 72px; }
.foot-cols div { display: flex; flex-direction: column; gap: 14px; min-width: 72px; }
.foot-cols .bar { font-size: 16px; margin-bottom: 4px; }
.foot-cols a { font-size: 14px; color: var(--gray); transition: color .15s; }
.foot-cols a:hover { color: var(--red); }
.foot-bottom {
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 24px;
  border-radius: 0 0 26px 26px; padding: 18px 56px 22px;
  border-top: 1px solid rgba(0, 0, 0, 0.06); font-size: 13px; color: var(--light);
}
.foot-bottom a:hover { color: var(--ink); }

/* Phone */
@media (max-width: 760px) {
  .nav, main, .foot { padding: 0 16px; }
  .foot { margin-top: 56px; margin-bottom: 16px; }
  .foot-top { flex-direction: column; gap: 32px; padding: 32px 24px 28px; }
  .foot-cols { gap: 0; justify-content: space-between; }
  .foot-bottom { flex-direction: column; padding: 16px 24px 20px; }
  .nav { flex-direction: column; align-items: flex-start; height: auto; padding-top: 16px; padding-bottom: 12px; gap: 12px; }
  .links { width: 100%; justify-content: space-between; }
  .links a { padding: 7px 10px; font-size: 14px; }
  .hero { grid-template-columns: 1fr; padding: 32px 24px 28px; row-gap: 20px; }
  .slogan { font-size: 28px; }
  .slogan em { font-size: 38px; margin-right: 8px; }
  .slogan .second { padding-left: 60px; }
  .wave { justify-self: stretch; max-width: none; }
  .cta { justify-self: stretch; justify-content: center; font-size: 18px; }
  .block { margin-top: 48px; }
  .rows li { flex-wrap: wrap; gap: 14px 18px; padding: 20px 0; align-items: flex-start; }
  .rows li > div { flex: 1 1 0; min-width: 0; }
  .pic { width: 100%; max-width: none; }
  .num { font-size: 28px; min-width: 38px; }
  .plate { padding: 22px 20px; }
}

/* ===== Document pages (隐私政策 / 用户协议 / 技术支持) ===== */
.doc-head { padding: 40px 0 36px; border-bottom: 1px solid var(--rule); }
.doc-head h1 { font-size: 40px; font-weight: 600; line-height: 1.25; letter-spacing: -0.01em; }
.doc-head .meta { margin-top: 12px; display: flex; flex-wrap: wrap; gap: 4px 24px; font-size: 14px; color: var(--gray); }
.doc-head .intro { margin-top: 16px; font-size: 17px; color: #444; max-width: 40em; }

.doc { display: grid; grid-template-columns: 200px minmax(0, 1fr); gap: 64px; padding-top: 40px; }
.toc { position: sticky; top: 24px; align-self: start; }
.toc p { font-size: 13px; font-weight: 500; color: var(--gray); margin-bottom: 10px; }
.toc ol { list-style: none; border-left: 1px solid var(--rule); }
.toc a { display: block; padding: 5px 0 5px 14px; margin-left: -1px; border-left: 2px solid transparent;
  font-size: 14px; color: var(--gray); transition: color .14s, border-color .14s; }
.toc a:hover { color: var(--ink); border-left-color: var(--red); }

.prose { max-width: 40em; font-size: 16px; line-height: 1.8; color: #333; }
.prose section { scroll-margin-top: 24px; }
.prose section + section { margin-top: 48px; }
.prose h2.bar { font-size: 20px; margin-bottom: 14px; color: var(--ink); }
.prose p + p, .prose p + ol, .prose ol + p { margin-top: 12px; }
.prose a { color: var(--ink); text-decoration: underline; text-decoration-color: rgba(0,0,0,.2);
  text-underline-offset: 3px; transition: text-decoration-color .14s; }
.prose a:hover { text-decoration-color: var(--ink); }

.clauses { list-style: none; counter-reset: c; }
.clauses li { position: relative; padding-left: 2em; counter-increment: c; }
.clauses li + li { margin-top: 10px; }
.clauses li::before { content: counter(c); position: absolute; left: 0; top: 0;
  color: var(--red); font-weight: 600; font-variant-numeric: tabular-nums; }

/* The summary plate: same grey plate + red numerals as the app's 课程导读 */
.summary { background: var(--plate); border-radius: 16px; padding: 24px 28px; }
.summary h2.bar { margin-bottom: 12px; }
.summary .clauses li::before { font-size: 18px; line-height: 1.6; }

.contact { list-style: none; background: var(--plate); border-radius: 16px; padding: 8px 24px; }
.contact + p { margin-top: 12px; }
.contact li { display: flex; gap: 24px; padding: 12px 0; }
.contact li + li { border-top: 1px solid rgba(0,0,0,.06); }
.contact span:first-child { flex: 0 0 8em; color: var(--gray); }

/* Blanks the owner still has to fill in */
.todo { display: inline-block; padding: 0 8px; border: 1px dashed #bdbdbd; border-radius: 6px;
  color: var(--gray); font-size: 0.94em; line-height: 1.6; background: #fff; }

/* Support page */
.help { display: flex; align-items: center; justify-content: space-between; gap: 32px;
  background: var(--plate); border-radius: 26px; padding: 36px 40px; margin-top: 40px; }
.help h2 { font-size: 24px; font-weight: 600; }
.help p { margin-top: 8px; font-size: 16px; color: #444; max-width: 34em; }
.help .cta { flex-shrink: 0; font-size: 18px; height: 48px; padding: 0 28px; }
.faq { margin-top: 56px; }
.faq dl { margin-top: 8px; }
.faq .qa { padding: 22px 0; border-bottom: 1px solid var(--rule); max-width: 44em; }
.faq .qa:last-child { border-bottom: 0; }
.faq dt { font-size: 17px; font-weight: 600; color: var(--ink); }
.faq dd { margin-top: 6px; font-size: 16px; line-height: 1.8; color: #444; }

@media (max-width: 760px) {
  .doc-head { padding: 24px 0 24px; }
  .doc-head h1 { font-size: 30px; }
  .doc { grid-template-columns: 1fr; gap: 0; padding-top: 28px; }
  .toc { display: none; }
  .summary { padding: 20px 20px; }
  .contact { padding: 4px 18px; }
  .contact li { flex-direction: column; gap: 2px; }
  .contact span:first-child { flex: none; font-size: 14px; }
  .help { flex-direction: column; align-items: stretch; padding: 28px 22px; border-radius: 22px; }
  .help .cta { justify-content: center; }
  .faq { margin-top: 40px; }
}