:root {
  --ink: #1d1d1f;
  --muted: #6e6e73;
  --line: rgba(0, 0, 0, 0.12);
  --soft: #f5f5f7;
  --blue: #0071e3;
  --red: #c9342f;
  --max: 1240px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--soft); color: var(--ink); font-family: Inter, "PingFang SC", "Microsoft YaHei", Arial, sans-serif; line-height: 1.65; }
a { color: inherit; text-decoration: none; }
button, input { font: inherit; }

.help-header {
  position: sticky;
  z-index: 20;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  padding: 0 max(24px, calc((100% - var(--max)) / 2));
  border-bottom: 1px solid var(--line);
  background: rgba(245, 245, 247, 0.9);
  backdrop-filter: blur(18px);
}

.brand { display: inline-flex; align-items: center; gap: 9px; font-size: 15px; font-weight: 700; }
.brand img { width: 27px; height: 27px; object-fit: contain; }
.help-header nav { display: flex; align-items: center; gap: 24px; font-size: 13px; color: var(--muted); }
.help-header nav a:hover, .help-header nav .is-active { color: var(--ink); }

.help-hero { padding: 94px 24px 82px; text-align: center; background: #fff; border-bottom: 1px solid var(--line); }
.eyebrow, .section-label { margin: 0 0 12px; color: var(--blue); font-size: 11px; font-weight: 700; letter-spacing: 0; }
.help-hero h1 { margin: 0; font-size: 64px; line-height: 1; letter-spacing: 0; }
.help-hero > p:not(.eyebrow):not(.search-status) { max-width: 650px; margin: 24px auto 0; color: var(--muted); font-size: 19px; }
.help-search { display: flex; align-items: center; width: min(680px, 100%); min-height: 54px; margin: 38px auto 0; padding: 0 16px; border: 1px solid var(--line); border-radius: 8px; background: var(--soft); }
.help-search > span { color: var(--muted); font-size: 24px; }
.help-search input { flex: 1; min-width: 0; padding: 0 12px; border: 0; outline: 0; background: transparent; color: var(--ink); }
.help-search kbd { padding: 2px 7px; border: 1px solid var(--line); border-radius: 4px; color: var(--muted); background: #fff; }
.search-status { min-height: 20px; margin: 10px 0 0; color: var(--muted); font-size: 12px; }

.help-layout { display: grid; grid-template-columns: 230px minmax(0, 1fr); gap: 70px; width: min(var(--max), calc(100% - 48px)); margin: 0 auto; padding: 72px 0 110px; }
.help-sidebar { position: sticky; top: 96px; align-self: start; }
.help-sidebar > strong { display: block; margin-bottom: 18px; font-size: 13px; }
.help-sidebar nav { display: grid; border-left: 1px solid var(--line); }
.help-sidebar a { padding: 7px 0 7px 17px; color: var(--muted); font-size: 13px; }
.help-sidebar a:hover, .help-sidebar a.is-active { color: var(--blue); border-left: 2px solid var(--blue); margin-left: -1px; }

.help-content { min-width: 0; }
.help-section { padding: 0 0 82px; margin: 0 0 82px; border-bottom: 1px solid var(--line); scroll-margin-top: 94px; }
.help-section[hidden] { display: none; }
.help-section h2, .help-footer-cta h2 { max-width: 860px; margin: 0 0 28px; font-size: 42px; line-height: 1.12; letter-spacing: 0; }
.help-section h3 { margin: 34px 0 10px; font-size: 20px; line-height: 1.3; letter-spacing: 0; }
.help-section p { max-width: 860px; margin: 0 0 18px; color: var(--muted); }
.help-section p strong, .help-section li strong { color: var(--ink); }
.help-section .lead { font-size: 18px; }
.help-section a { color: var(--blue); }
code { padding: 2px 6px; border: 1px solid var(--line); border-radius: 4px; background: #fff; color: var(--ink); font-family: "Cascadia Code", Consolas, monospace; font-size: 0.9em; }

.step-list { margin-top: 38px; border-top: 1px solid var(--line); }
.step-list > div { display: grid; grid-template-columns: 44px 1fr; gap: 20px; padding: 24px 0; border-bottom: 1px solid var(--line); }
.step-list > div > span { color: var(--blue); font-family: Consolas, monospace; font-size: 12px; }
.step-list h3 { margin: 0 0 5px; }
.step-list p { margin: 0; }
.action-row { display: flex; align-items: center; gap: 20px; margin-top: 30px; }
.action-row a { color: var(--blue); font-size: 14px; font-weight: 600; }
.action-row .primary-action { padding: 10px 18px; border-radius: 8px; background: var(--blue); color: #fff; }

.prompt-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 34px; margin-top: 34px; border-top: 1px solid var(--line); }
.prompt-grid > div { padding: 26px 0; border-bottom: 1px solid var(--line); }
.prompt-grid h3 { margin: 0 0 8px; font-size: 17px; }
.prompt-grid p { margin: 0; font-size: 14px; }
.callout, .boundary-box, .security-strip { margin: 32px 0; padding: 24px; border-left: 3px solid var(--blue); background: #fff; }
.callout p, .boundary-box p, .security-strip p { margin: 6px 0 0; }
.boundary-box h3 { margin: 0 0 12px; }
.boundary-box ul { margin: 0; padding-left: 22px; color: var(--muted); }
.boundary-box li + li { margin-top: 8px; }
.boundary-box.danger { border-left-color: var(--red); }

.definition-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 34px; border-top: 1px solid var(--line); }
.definition-list > div { padding: 24px 0; border-bottom: 1px solid var(--line); }
.definition-list h3 { margin: 0 0 7px; font-size: 17px; }
.definition-list p { margin: 0; font-size: 14px; }

.mode-table { margin: 34px 0; border-top: 1px solid var(--line); }
.mode-table > div { display: grid; grid-template-columns: 1fr 1.2fr 1.7fr 1.2fr; gap: 20px; padding: 18px 0; border-bottom: 1px solid var(--line); color: var(--muted); font-size: 13px; }
.mode-table .mode-head { color: var(--ink); font-size: 11px; font-weight: 700; }
.mode-table strong { color: var(--ink); }
.security-strip { display: grid; grid-template-columns: auto auto 1fr; gap: 16px; align-items: center; }
.security-strip p { margin: 0; font-size: 13px; }
.official-links { display: flex; flex-wrap: wrap; gap: 18px; margin-top: 20px !important; }
.numbered-steps { max-width: 900px; margin: 20px 0 36px; padding-left: 24px; }
.numbered-steps li { padding: 6px 0 6px 8px; color: var(--muted); }
.example-flow { margin: 24px 0; padding: 8px 24px; border-left: 1px solid var(--line); }
.example-flow p { margin: 14px 0; }

.risk-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); margin: 32px 0; border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.risk-grid > div { min-width: 0; padding: 18px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); background: #fff; }
.risk-grid span { display: block; margin-bottom: 8px; color: var(--muted); font-size: 11px; }
.risk-grid strong { font-size: 14px; overflow-wrap: anywhere; }
.check-list { max-width: 900px; padding: 0; list-style: none; }
.check-list li { position: relative; padding: 15px 0 15px 26px; border-bottom: 1px solid var(--line); color: var(--muted); }
.check-list li::before { position: absolute; left: 0; color: var(--blue); content: "✓"; }

.faq-group { margin-top: 44px; }
.faq-group > h3 { padding-bottom: 12px; border-bottom: 1px solid var(--line); }
details { border-bottom: 1px solid var(--line); }
summary { padding: 18px 34px 18px 0; cursor: pointer; font-weight: 600; list-style: none; }
summary::-webkit-details-marker { display: none; }
summary::after { float: right; color: var(--blue); content: "+"; }
details[open] summary::after { content: "−"; }
details p { padding: 0 0 18px; margin: 0 !important; }

.help-footer-cta { display: flex; justify-content: space-between; gap: 40px; align-items: end; padding: 10px 0 20px; }
.help-footer-cta h2 { margin-bottom: 12px; font-size: 34px; }
.help-footer-cta p { max-width: 650px; margin: 0; color: var(--muted); }
.help-footer-cta .action-row { flex-shrink: 0; }
footer { display: flex; justify-content: space-between; padding: 28px max(24px, calc((100% - var(--max)) / 2)); border-top: 1px solid var(--line); background: #fff; color: var(--muted); font-size: 12px; }

mark { padding: 0 2px; background: #fff0a8; color: inherit; }

@media (max-width: 960px) {
  .help-layout { grid-template-columns: 1fr; gap: 42px; }
  .help-sidebar { position: static; overflow-x: auto; }
  .help-sidebar > strong { display: none; }
  .help-sidebar nav { display: flex; width: max-content; border-left: 0; border-bottom: 1px solid var(--line); }
  .help-sidebar a { padding: 10px 14px; white-space: nowrap; }
  .help-sidebar a:hover, .help-sidebar a.is-active { margin-left: 0; border-left: 0; border-bottom: 2px solid var(--blue); }
  .risk-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .help-footer-cta { align-items: flex-start; flex-direction: column; }
}

@media (max-width: 720px) {
  .help-header { min-height: 58px; padding: 0 14px; }
  .brand span { display: none; }
  .help-header nav { gap: 14px; font-size: 11px; }
  .help-header nav a:nth-child(2) { display: none; }
  .help-hero { padding: 72px 16px 56px; }
  .help-hero h1 { font-size: 46px; }
  .help-hero > p:not(.eyebrow):not(.search-status) { font-size: 16px; }
  .help-search kbd { display: none; }
  .help-layout { width: calc(100% - 32px); padding: 38px 0 76px; }
  .help-section { padding-bottom: 58px; margin-bottom: 58px; }
  .help-section h2 { font-size: 34px; }
  .prompt-grid, .definition-list { grid-template-columns: 1fr; }
  .mode-table > div { grid-template-columns: 1fr; gap: 5px; padding: 20px 0; }
  .mode-table .mode-head { display: none; }
  .security-strip { grid-template-columns: 1fr; }
  .risk-grid { grid-template-columns: 1fr; }
  .action-row { align-items: flex-start; flex-direction: column; }
  footer { padding: 24px 16px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}