/* Frontend & backend course: request map, stack tables, glossary and quiz. */
.ws-stack-map { display: flex; flex-wrap: wrap; gap: 6px; }
.ws-stack-map span { padding: 4px 8px; border-radius: var(--r-xs); background: var(--surface-3); color: var(--ink-2); font-size: var(--type-meta-size); font-family: var(--font-mono); }

.sb-page { padding-top: 30px; padding-bottom: 72px; }

.sb-intro { display: grid; gap: 10px; padding-bottom: 8px; }
.sb-intro .ws-back { font-size: 11px; }
.sb-intro > .eyebrow { margin: 14px 0 0; font-size: 10px; }
.sb-intro h1 { font-size: var(--type-page-size); line-height: var(--type-page-leading); letter-spacing: var(--type-page-tracking); }
.sb-intro-copy { max-width: 82ch; margin-top: 12px; color: var(--ink-2); font-size: 15px; line-height: 1.9; }
.sb-intro-stats { display: flex; flex-wrap: wrap; gap: 10px 22px; margin-top: 18px; }
.sb-intro-stats span { display: inline-flex; align-items: baseline; gap: 7px; padding-left: 10px; border-left: 2px solid var(--accent); color: var(--ink-2); font-size: 12px; }
.sb-intro-stats b { color: var(--ink); font-size: 20px; font-variant-numeric: tabular-nums; }

.sb-toc {
  position: sticky;
  top: var(--header-h);
  z-index: 9;
  display: flex;
  gap: 4px;
  overflow-x: auto;
  margin-top: 26px;
  padding: 10px 0;
  background: var(--bg);
  border-bottom: 1px solid var(--line);
  scrollbar-width: thin;
}
.sb-toc :is(button, a) {
  flex: none;
  padding: 7px 11px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: transparent;
  color: var(--ink-3);
  font-size: 11px;
  text-decoration: none;
  white-space: nowrap;
}
.sb-toc :is(button, a):hover { border-color: var(--line); color: var(--ink); text-decoration: none; }
.sb-toc a[aria-current="page"] { background: var(--ink); border-color: var(--ink); color: #fff; }

.sb-section { scroll-margin-top: calc(var(--header-h) + 24px); margin-top: 72px; min-width: 0; }
.sb-section:focus { outline: none; }
.sb-section-heading { margin-bottom: 26px; }
.sb-section-heading h2 { margin: 12px 0 16px; font-size: var(--type-section-size); line-height: var(--type-section-leading); letter-spacing: var(--type-section-tracking); }
.sb-section-heading > p:last-child { max-width: 88ch; color: var(--ink-2); font-size: 14px; line-height: 1.9; }
.sb-subheading { margin: 34px 0 14px; font-size: 19px; }
.sb-topic-grid > *,
.sb-mode-grid > *,
.sb-connect-grid > *,
.sb-picker-primary > *,
.sb-picker-columns > * { min-width: 0; }

.sb-callout {
  display: grid;
  gap: 6px;
  margin: 26px 0;
}
.sb-callout strong { font-size: var(--type-small-size); }
.sb-callout p { color: var(--ink-2); font-size: var(--type-small-size); line-height: 1.8; }
.sb-note { margin-top: 18px; color: var(--ink-2); font-size: 12px; line-height: 1.8; }

/* Request journey: a vertical route with a live explanation panel */
.sb-flow { display: grid; gap: 14px; min-width: 0; }

.sb-flow [data-lane="浏览器"] { --lane: #0071e3; --lane-soft: #e7f1fc; --lane-line: #b9d6f2; --lane-ink: #0a5bb5; }
.sb-flow [data-lane="网络"] { --lane: #0d8a8a; --lane-soft: #e4f5f3; --lane-line: #b3e0dc; --lane-ink: #0a6666; }
.sb-flow [data-lane="服务器"] { --lane: #7257c8; --lane-soft: #efebfb; --lane-line: #d3c9f2; --lane-ink: #5a43a8; }
.sb-flow [data-lane="数据"] { --lane: #b97818; --lane-soft: #fbf1e2; --lane-line: #ecd3ae; --lane-ink: #8f5c0e; }

.sb-flow-toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 12px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); }
.sb-flow-toolbar .ui-button-primary { min-height: 38px; padding-inline: 16px; }
.sb-flow-meter { display: grid; gap: 6px; flex: 1 1 220px; min-width: 0; margin-left: auto; }
.sb-flow-status { color: var(--ink-2); font: 10px var(--font-mono); }
.sb-flow-progress { height: 5px; overflow: hidden; border-radius: 99px; background: var(--surface-3); }
.sb-flow-progress i { display: block; width: 0; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--accent), #54b7ff); transition: width 280ms var(--ease-out); }

.sb-flow-board { display: grid; grid-template-columns: minmax(0, 1.02fr) minmax(0, .98fr); gap: 18px; align-items: start; min-width: 0; }
.sb-flow-main { min-width: 0; padding: 16px 18px 18px; border: 1px solid var(--line); border-radius: 20px; background: linear-gradient(180deg, var(--surface), #f7f8fa); }
.sb-flow-caption { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 4px 12px; margin-bottom: 12px; color: var(--ink-3); font-size: 10px; }
.sb-flow-caption strong { color: var(--ink-2); font-size: 11px; font-weight: 600; }

.sb-flow-route { display: grid; margin: 0; padding: 0; list-style: none; }
.sb-flow-phase-row { position: relative; display: grid; grid-template-columns: 38px minmax(0, 1fr); align-items: start; column-gap: 12px; padding: 4px 0; }
.sb-flow-phase-row::before { content: ""; position: absolute; left: 18px; top: 0; bottom: 0; width: 2px; background: var(--lane); opacity: .22; transition: opacity var(--dur-2); }
.sb-flow-phase-row:first-child::before { top: 20px; }
.sb-flow-phase-row.is-return::before { background: repeating-linear-gradient(to bottom, var(--lane) 0 4px, transparent 4px 8px); opacity: .5; }
.sb-flow-phase-row[data-state="done"]::before,
.sb-flow-phase-row[data-state="active"]::before { opacity: .6; }
.sb-flow-phase-row.is-return[data-state="done"]::before,
.sb-flow-phase-row.is-return[data-state="active"]::before { opacity: .85; }

.sb-flow-marker { position: relative; z-index: 1; grid-column: 1; grid-row: 1 / span 2; display: grid; place-items: center; width: 38px; height: 38px; margin-top: 4px; border: 1.5px solid var(--line-strong); border-radius: 50%; background: var(--surface); color: var(--ink-3); font: 10px var(--font-mono); letter-spacing: .04em; transition: background-color var(--dur-2), border-color var(--dur-2), color var(--dur-2), box-shadow var(--dur-2); }
.sb-flow-phase-row[data-state="done"] .sb-flow-marker { border-color: var(--lane); background: var(--lane-soft); color: var(--lane-ink); }
.sb-flow-phase-row[data-state="active"] .sb-flow-marker { border-color: var(--lane); background: var(--lane); color: #fff; box-shadow: 0 0 0 5px var(--lane-soft); }

.sb-flow-phase { grid-column: 2; grid-row: 1; display: grid; gap: 3px; min-width: 0; padding: 8px 11px; border: 1px solid transparent; border-radius: 11px; background: transparent; color: var(--ink); text-align: left; transition: background-color var(--dur-2), box-shadow var(--dur-2); }
.sb-flow-phase:hover { background: var(--surface); box-shadow: inset 0 0 0 1px var(--line); }
.sb-flow-phase-row[data-state="active"] .sb-flow-phase { background: var(--lane-soft); box-shadow: inset 0 0 0 1px var(--lane-line); }
.sb-flow-phase-head { display: flex; flex-wrap: wrap; align-items: center; gap: 5px 8px; }
.sb-flow-phase-head strong { font-size: 15px; line-height: 1.35; letter-spacing: -.01em; }
.sb-flow-phase-row[data-state="pending"] .sb-flow-phase-head strong { color: var(--ink-2); }
.sb-flow-env { display: inline-flex; align-items: center; gap: 4px; padding: 2px 7px; border-radius: 999px; background: var(--lane-soft); color: var(--lane-ink); font-size: 9px; font-weight: 600; white-space: nowrap; }
.sb-flow-env::before { content: ""; width: 5px; height: 5px; border-radius: 50%; background: var(--lane); }
.sb-flow-phase-row[data-state="active"] .sb-flow-env { background: #fff; }
.sb-flow-return { color: var(--lane-ink); font: 9px var(--font-mono); letter-spacing: .04em; }
.sb-flow-phase-summary { color: var(--ink-2); font-size: 12px; line-height: 1.6; }

.sb-flow-subs { grid-column: 2; grid-row: 2; display: flex; flex-wrap: wrap; gap: 5px; padding: 4px 11px 2px; }
.sb-flow-sub { display: inline-flex; align-items: center; gap: 5px; min-height: 26px; padding: 3px 8px; border: 1px solid var(--line); border-radius: 999px; background: var(--surface); color: var(--ink-2); font-size: 11px; line-height: 1.3; transition: border-color var(--dur-2), background-color var(--dur-2), color var(--dur-2); }
.sb-flow-sub:hover { border-color: var(--lane-line); color: var(--ink); }
.sb-flow-sub-code { color: var(--ink-3); font: 8.5px var(--font-mono); letter-spacing: .04em; }
.sb-flow-sub[data-state="done"] { background: var(--lane-soft); border-color: var(--lane-line); color: var(--lane-ink); }
.sb-flow-sub[data-state="done"] .sb-flow-sub-code { color: var(--lane-ink); opacity: .6; }
.sb-flow-sub[data-state="active"] { background: var(--lane); border-color: var(--lane); color: #fff; }
.sb-flow-sub[data-state="active"] .sb-flow-sub-code { color: rgba(255, 255, 255, .72); }

.sb-flow-outcome { position: relative; display: grid; grid-template-columns: 38px minmax(0, 1fr); align-items: center; column-gap: 12px; padding-top: 4px; }
.sb-flow-outcome::before { content: ""; position: absolute; left: 18px; top: 0; width: 2px; height: 50%; background: var(--line-strong); opacity: .5; }
.sb-flow-outcome-mark { position: relative; z-index: 1; display: grid; place-items: center; width: 38px; height: 38px; border: 1.5px dashed var(--line-strong); border-radius: 50%; background: var(--surface); color: var(--ink-3); font-size: 14px; transition: background-color var(--dur-2), border-color var(--dur-2), color var(--dur-2); }
.sb-flow-outcome-text { display: grid; gap: 2px; padding: 7px 11px; border-radius: 11px; transition: background-color var(--dur-2); }
.sb-flow-outcome-text strong { color: var(--ink-2); font-size: 14px; }
.sb-flow-outcome-text span { color: var(--ink-3); font-size: 11px; }
.sb-flow-outcome[data-state="active"] .sb-flow-outcome-mark { border-style: solid; border-color: var(--line-strong); color: var(--ink-2); }
.sb-flow-outcome[data-state="done"] .sb-flow-outcome-mark { border-style: solid; border-color: #2f7d4f; background: #2f7d4f; color: #fff; }
.sb-flow-outcome[data-state="done"] .sb-flow-outcome-text { background: #eef7f0; }
.sb-flow-outcome[data-state="done"] .sb-flow-outcome-text strong { color: var(--ink); }

.sb-flow-detail { position: sticky; top: calc(var(--header-h) + 18px); min-width: 0; padding: 24px 24px 22px; border: 1px solid var(--line); border-radius: 20px; background: var(--surface); box-shadow: 0 24px 50px -40px rgba(0, 0, 0, .45); overflow: hidden; }
.sb-flow-detail::before { content: ""; position: absolute; inset: 0 0 auto; height: 4px; background: var(--lane); }
.sb-flow-detail::after { content: attr(data-step); position: absolute; top: 6px; right: 12px; color: var(--ink); font: 700 76px/1 var(--font-mono); opacity: .045; pointer-events: none; }
.sb-flow-detail-head { position: relative; z-index: 1; display: flex; flex-wrap: wrap; align-items: center; gap: 6px 8px; }
.sb-flow-step { color: var(--lane-ink); font: 10px var(--font-mono); letter-spacing: .08em; }
.sb-flow-detail h3 { position: relative; z-index: 1; margin: 12px 0 10px; font-size: clamp(21px, 2.1vw, 27px); line-height: 1.4; letter-spacing: -.02em; }
.sb-flow-detail-copy { position: relative; z-index: 1; color: var(--ink-2); font-size: 13.5px; line-height: 1.95; }
.sb-flow-detail .sb-tech-chips { position: relative; z-index: 1; margin-top: 15px; }
.sb-flow-detail .sb-tech-chips span { background: var(--lane-soft); color: var(--lane-ink); }
.sb-flow-note { position: relative; z-index: 1; display: grid; gap: 3px; margin-top: 16px; padding: 12px 14px; border: 1px solid #f0ded9; border-radius: 11px; background: #fbf3f1; color: #7a3b30; font-size: 11.5px; line-height: 1.75; }
.sb-flow-note strong { color: #8a3b2e; font-size: 10px; letter-spacing: .08em; }
.sb-flow-note-text { display: block; }
.sb-flow-detail-controls { position: relative; z-index: 1; display: flex; justify-content: space-between; gap: 8px; margin-top: 18px; padding-top: 16px; border-top: 1px solid var(--line); }
.sb-tech-chips { display: flex; flex-wrap: wrap; gap: 6px; margin: 14px 0 0; }
.sb-tech-chips span { padding: 4px 8px; border-radius: 6px; background: var(--surface-3); color: var(--ink-2); font: 10px var(--font-mono); }

/* Concept cards */
.sb-topic-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.sb-topic { display: flex; flex-direction: column; gap: 12px; padding: 22px; min-width: 0; }
.sb-topic-head { display: grid; grid-template-columns: auto 1fr; gap: 2px 8px; align-items: baseline; }
.sb-layer { grid-row: 1 / 3; align-self: start; padding: 3px 7px; border-radius: 5px; background: var(--accent-soft); color: var(--accent-ink); font-size: 10px; }
.sb-topic-head h3 { font-size: var(--type-card-size); line-height: var(--type-card-leading); letter-spacing: var(--type-card-tracking); }
.sb-english { color: var(--ink-3); font: 10px var(--font-mono); letter-spacing: .04em; }
.sb-topic-definition { color: var(--ink-2); font-size: var(--type-small-size); line-height: 1.85; }
.sb-topic-list { display: grid; gap: 9px; padding-top: 12px; border-top: 1px solid var(--line); }
.sb-topic-list div { display: grid; grid-template-columns: 68px 1fr; gap: 8px; }
.sb-topic-list dt { color: var(--ink-3); font-size: 11px; }
.sb-topic-list dd { color: var(--ink-2); font-size: 12px; line-height: 1.75; }

.sb-code {
  min-width: 0;
  max-width: 100%;
  margin: 0;
  padding: 12px 14px;
  overflow-x: auto;
  border-radius: 10px;
  background: var(--stage);
  color: var(--stage-ink);
  font: 11px/1.7 var(--font-mono);
  tab-size: 2;
}
.sb-code-wide { margin-top: 14px; }

.sb-table-stack { display: grid; gap: 22px; min-width: 0; }
.sb-table-wrap { max-width: 100%; min-width: 0; overflow-x: auto; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); }
.sb-table { width: 100%; min-width: 760px; border-collapse: collapse; font-size: 12px; }
.sb-table caption { padding: 16px 18px; color: var(--ink); font-size: 16px; font-weight: 600; text-align: left; }
.sb-table th, .sb-table td { padding: 11px 14px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; line-height: 1.7; }
.sb-table thead th { background: var(--surface-3); color: var(--ink-2); font-size: 11px; font-weight: 600; white-space: nowrap; }
.sb-table tbody th { color: var(--ink); font-weight: 600; white-space: nowrap; }
.sb-table tbody tr:last-child th, .sb-table tbody tr:last-child td { border-bottom: 0; }
.sb-table td { color: var(--ink-2); }
.sb-table em { color: var(--ink-3); font: 10px var(--font-mono); font-style: normal; }

.sb-mode-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.sb-mode { padding: 18px; border: 1px solid var(--line); border-radius: 14px; background: var(--surface); }
.sb-mode small { color: var(--ink-3); font: 9px var(--font-mono); letter-spacing: .08em; }
.sb-mode h4 { margin: 8px 0 8px; font-size: 18px; }
.sb-mode > p { color: var(--ink-2); font-size: 12px; line-height: 1.8; }
.sb-mode dl { display: grid; gap: 8px; margin-top: 12px; padding-top: 10px; border-top: 1px solid var(--line); }
.sb-mode dl div { display: grid; grid-template-columns: 42px 1fr; gap: 7px; }
.sb-mode dt { color: var(--ink-3); font-size: 10px; }
.sb-mode dd { color: var(--ink-2); font-size: 11px; line-height: 1.7; }

.sb-connect-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.sb-connect-card { padding: 20px; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); }
.sb-connect-card small { color: var(--ink-3); font: 9px var(--font-mono); letter-spacing: .08em; }
.sb-connect-card h3 { margin: 8px 0 10px; font-size: 20px; }
.sb-connect-card p { color: var(--ink-2); font-size: 12px; line-height: 1.85; }
.sb-example-line { display: grid; gap: 5px; margin: 13px 0; }
.sb-example-line span { color: var(--ink-3); font-size: 10px; }
.sb-example-line code { display: block; padding: 7px 9px; overflow-x: auto; border-radius: 6px; background: var(--surface-3); color: var(--ink-2); font: 10px var(--font-mono); white-space: pre-wrap; overflow-wrap: anywhere; }
.sb-mistake { padding-top: 10px; border-top: 1px solid var(--line); }
.sb-mistake strong { color: var(--ink); }

.sb-topology, .sb-pipeline { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-top: 18px; padding: 16px; border: 1px dashed var(--line-strong); border-radius: 12px; }
.sb-topology span, .sb-pipeline span { padding: 6px 10px; border-radius: 7px; background: var(--surface); font: 10px var(--font-mono); color: var(--ink-2); }
.sb-topology i, .sb-pipeline i { color: var(--ink-3); font-style: normal; font-size: 12px; }

/* Stack picker */
.sb-picker { display: grid; gap: 18px; }
.sb-picker-chips { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 8px; }
.sb-picker-chip { display: grid; gap: 4px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface); text-align: left; }
.sb-picker-chip strong { font-size: 13px; }
.sb-picker-chip span { color: var(--ink-2); font-size: 11px; line-height: 1.6; }
.sb-picker-chip[aria-pressed="true"] { border-color: var(--accent); background: var(--accent-soft); }
.sb-picker-result { padding: 24px; }
.sb-picker-result h3 { margin: 10px 0 8px; font-size: var(--type-card-size); line-height: var(--type-card-leading); }
.sb-picker-question { color: var(--ink-2); font-size: 13px; line-height: 1.8; }
.sb-picker-primary { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; margin-top: 18px; }
.sb-picker-primary-card { padding: 14px; border: 1px solid var(--line); border-radius: 12px; background: var(--bg); }
.sb-picker-primary-card small { color: var(--accent-ink); font: 9px var(--font-mono); letter-spacing: .08em; }
.sb-picker-primary-card h4 { margin: 6px 0; font-size: 16px; }
.sb-picker-primary-card p { color: var(--ink-2); font-size: 11px; line-height: 1.7; }
.sb-picker-columns { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--line); }
.sb-picker-columns h4 { margin-bottom: 8px; font-size: 13px; }
.sb-picker-columns ul { display: grid; gap: 8px; }
.sb-picker-columns li { color: var(--ink-2); font-size: 11px; line-height: 1.7; }
.sb-picker-columns li strong { display: block; color: var(--ink); }
.sb-picker-columns li span { display: block; }
.sb-picker-avoid li { color: #8a3b2e; }

/* Glossary */
.sb-glossary-tools { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 12px; }
.sb-glossary-tools input { width: min(360px, 100%); padding: 10px 14px; border: 1px solid var(--line); border-radius: 999px; background: var(--surface); font-size: 13px; outline: none; }
.sb-glossary-tools input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.sb-results-count { color: var(--ink-3); font: 11px var(--font-mono); }
.sb-filter-row { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 18px; }
.sb-filter-row .sb-button { min-height: 30px; padding: 5px 10px; border-radius: 999px; font-size: 11px; }
.sb-filter-row .sb-button[aria-pressed="true"] { background: var(--ink); border-color: var(--ink); color: #fff; }
.sb-glossary-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 9px; }
.sb-term { border: 1px solid var(--line); border-radius: 12px; background: var(--surface); }
.sb-term summary { display: grid; grid-template-columns: 1fr auto; gap: 2px 10px; padding: 13px 15px; cursor: pointer; list-style: none; }
.sb-term summary::-webkit-details-marker { display: none; }
.sb-term-top { display: flex; justify-content: space-between; grid-column: 1 / -1; color: var(--ink-3); font-size: 9px; }
.sb-term-plus { transition: transform 180ms var(--ease-out); }
.sb-term[open] .sb-term-plus { transform: rotate(45deg); }
.sb-term summary strong { font-size: 15px; }
.sb-term-english { align-self: end; color: var(--ink-3); font: 9px var(--font-mono); }
.sb-term > p { padding: 0 15px 10px; color: var(--ink-2); font-size: 12px; line-height: 1.8; }
.sb-term-example { margin: 0 15px 12px; padding: 10px 12px; border-radius: 8px; background: var(--surface-3); }
.sb-term-example small { color: var(--ink-3); font-size: 9px; }
.sb-term-example p { margin-top: 4px; color: var(--ink-2); font: 10px var(--font-mono); line-height: 1.6; overflow-wrap: anywhere; }
.sb-term-expanded { padding: 0 15px 14px; border-top: 1px solid var(--line); }
.sb-term-expanded p { padding-top: 10px; color: var(--ink-2); font-size: 11px; line-height: 1.8; }
.sb-empty { grid-column: 1 / -1; padding: 28px; border: 1px dashed var(--line-strong); border-radius: 14px; text-align: center; }
.sb-empty p { margin: 8px 0 14px; color: var(--ink-2); font-size: 12px; }

/* Quiz */
.sb-quiz-card { padding: 24px; border: 1px solid var(--line); border-radius: 18px; background: var(--surface); }
.sb-quiz-progress { color: var(--ink-3); font: 10px var(--font-mono); }
.sb-quiz-card h3 { margin: 14px 0 18px; font-size: 23px; line-height: 1.45; }
.sb-quiz-card h3:focus { outline: none; }
.sb-quiz-choices { display: grid; gap: 8px; }
.sb-quiz-choices .sb-button { justify-content: flex-start; min-height: 44px; text-align: left; }
.sb-quiz-choices .sb-button[aria-pressed="true"] { border-color: var(--accent); }
.sb-quiz-choices .sb-button[data-result="correct"] { border-color: #2f7d4f; background: #eef7f0; }
.sb-quiz-choices .sb-button[data-result="incorrect"] { border-color: #a4493b; background: #fbf0ee; }
.sb-quiz-feedback { min-height: 56px; margin-top: 16px; padding-top: 14px; border-top: 1px solid var(--line); color: var(--ink-2); font-size: 12px; line-height: 1.8; }
.sb-quiz-feedback strong { display: block; margin-bottom: 4px; color: var(--ink); }
.sb-quiz-score { margin-top: 8px; color: var(--accent-ink); }
.sb-quiz-controls { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 18px; }

.sb-sources { margin-top: 72px; padding-top: 24px; border-top: 1px solid var(--line-strong); }
.sb-sources h2 { font-size: 24px; }
.sb-sources > p { max-width: 78ch; margin: 12px 0 16px; color: var(--ink-2); font-size: 12px; line-height: 1.8; }
.sb-sources div { display: flex; flex-wrap: wrap; gap: 8px 18px; }
.sb-sources a { font-size: 12px; }

/* Course hub */
.sb-course-map { display: grid; gap: 8px; }
.sb-part { display: grid; grid-template-columns: 190px minmax(0, 1fr); gap: 14px 28px; min-width: 0; padding-top: 24px; border-top: 1px solid var(--line); }
.sb-part-head { display: grid; align-content: start; gap: 5px; }
.sb-part-label { color: var(--ink-3); font: 9px var(--font-mono); letter-spacing: .12em; }
.sb-part-head h3 { font-size: 21px; line-height: 1.3; }
.sb-part-head p { color: var(--ink-2); font-size: 12px; line-height: 1.7; }
.sb-chapter-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; min-width: 0; }
.sb-chapter-card { display: grid; align-content: start; gap: 8px; min-width: 0; padding: 18px; color: var(--ink); text-decoration: none; }
.sb-chapter-card:hover { text-decoration: none; }
.sb-chapter-top { display: flex; justify-content: space-between; gap: 8px; color: var(--ink-3); font: 9px var(--font-mono); }
.sb-chapter-top b { color: var(--accent-ink); font-weight: 600; }
.sb-chapter-card h4 { line-height: var(--type-card-leading); }
.sb-chapter-card p { color: var(--ink-2); font-size: var(--type-small-size); line-height: 1.75; }
.sb-chapter-blocks { display: flex; flex-wrap: wrap; gap: 5px; }
.sb-chapter-cta { margin-top: 2px; color: var(--accent-ink); font-size: var(--type-meta-size); font-weight: 600; }

/* Chapter pages */
.sb-chapter-page > .ws-back { display: inline-flex; margin-bottom: 14px; }
.sb-chapter-head { padding-bottom: 0; }
.sb-chapter-nav { margin-top: 18px; }
.sb-jump-nav { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin-top: 18px; }
.sb-jump-label { margin-right: 4px; color: var(--ink-3); font: 9px var(--font-mono); letter-spacing: .08em; }
.sb-jump-nav .sb-button { min-height: 30px; padding: 5px 10px; border-radius: 999px; font-size: 11px; }
.sb-block { margin-top: 40px; }
.sb-chapter-page .sb-block { scroll-margin-top: calc(var(--header-h) + 76px); }
.sb-chapter-next { display: flex; justify-content: space-between; gap: 10px; margin-top: 56px; padding-top: 20px; border-top: 1px solid var(--line-strong); }
.sb-chapter-next a { display: grid; gap: 3px; min-width: 0; padding: 13px 15px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface); color: var(--ink); }
.sb-chapter-next a:hover { border-color: var(--line-strong); text-decoration: none; }
.sb-chapter-next small { color: var(--ink-3); font-size: 10px; }
.sb-chapter-next strong { font-size: 13px; }
.sb-chapter-next a.is-next { margin-left: auto; text-align: right; }

@media (max-width: 900px) {
  .sb-part { grid-template-columns: 1fr; gap: 12px; }
  .sb-chapter-grid { grid-template-columns: 1fr; }
}


@media (max-width: 960px) {
  .sb-flow-board { grid-template-columns: 1fr; }
  .sb-flow-detail { position: static; }
  .sb-flow-meter { flex: 1 1 100%; margin-left: 0; }
  .sb-topic-grid, .sb-mode-grid, .sb-connect-grid, .sb-glossary-grid { grid-template-columns: 1fr; }
  .sb-picker-chips { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sb-picker-columns { grid-template-columns: 1fr; }
}

@media (max-width: 680px) {
  .sb-page { padding-top: 18px; }
  .sb-section { margin-top: 52px; }
  .sb-chapter-page .sb-block { margin-top: 36px; scroll-margin-top: calc(var(--header-h) + 70px); }
  .sb-toc { margin-inline: calc(var(--page-gutter) * -1); padding-inline: var(--page-gutter); }
  .sb-chapter-card { padding: 16px; }
  .sb-chapter-next { flex-direction: column; }
  .sb-chapter-next a.is-next { margin-left: 0; text-align: left; }
  .sb-picker-chips, .sb-picker-primary { grid-template-columns: 1fr; }
  .sb-topic { padding: 18px; }
  .sb-flow-main { padding: 14px 12px 16px; }
  .sb-flow-toolbar { padding: 10px 12px; }
  .sb-flow-status { white-space: normal; }
  .sb-flow-phase-row { grid-template-columns: 32px minmax(0, 1fr); column-gap: 9px; }
  .sb-flow-phase-row::before { left: 15px; }
  .sb-flow-marker { width: 32px; height: 32px; font-size: 9px; }
  .sb-flow-phase { padding: 7px 9px; }
  .sb-flow-phase-head strong { font-size: 14px; }
  .sb-flow-subs { padding: 4px 9px 2px; }
  .sb-flow-outcome { grid-template-columns: 32px minmax(0, 1fr); column-gap: 9px; }
  .sb-flow-outcome::before { left: 15px; }
  .sb-flow-outcome-mark { width: 32px; height: 32px; }
  .sb-flow-detail, .sb-picker-result, .sb-quiz-card { padding: 20px 18px; }
  .sb-table { min-width: 680px; }
}

@media (prefers-reduced-motion: reduce) {
  .sb-term-plus, .sb-button, .sb-toc :is(button, a), .sb-chapter-card, .sb-flow-phase, .sb-flow-marker, .sb-flow-sub, .sb-flow-outcome-mark, .sb-flow-outcome-text, .sb-flow-progress i { transition: none; }
  .sb-chapter-card:hover { transform: none; }
}

:root[data-motion="reduced"] .sb-chapter-card,
:root[data-motion="none"] .sb-chapter-card { transition: none; }
:root[data-motion="reduced"] .sb-chapter-card:hover,
:root[data-motion="none"] .sb-chapter-card:hover { transform: none; }

:root[data-motion="reduced"] .sb-flow-phase,
:root[data-motion="reduced"] .sb-flow-marker,
:root[data-motion="reduced"] .sb-flow-sub,
:root[data-motion="reduced"] .sb-flow-outcome-mark,
:root[data-motion="reduced"] .sb-flow-outcome-text,
:root[data-motion="reduced"] .sb-flow-progress i { transition: none; }
:root[data-motion="none"] .sb-flow-phase,
:root[data-motion="none"] .sb-flow-marker,
:root[data-motion="none"] .sb-flow-sub,
:root[data-motion="none"] .sb-flow-outcome-mark,
:root[data-motion="none"] .sb-flow-outcome-text,
:root[data-motion="none"] .sb-flow-progress i { transition: none; }