/* =========================================================================
   BPhO (British Physics Olympiad) sub-site — page-local additions on top of tian2.css + site.css
   Flat fills and rules only: no shadows, no gradients.
   ========================================================================= */

/* Masthead: brand + language toggle on the first row, the nine-item nav on its own row. */
.masthead .masthead-inner { align-items: center; gap: 12px 24px; padding-bottom: 0; }
.masthead .lang-toggle { order: 2; }
.masthead .nav {
  order: 3;
  flex: 1 0 100%;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 26px;
  border-top: 1px solid var(--ink);
  padding: 10px 0 12px;
}
.masthead .nav a { white-space: nowrap; }
@media (max-width: 560px) { .masthead .nav { gap: 6px 16px; } }

.headline--page { font-size: 56px; }
@media (max-width: 720px) { .headline--page { font-size: 38px; } }

html[lang="zh"] .headline,
html[lang="zh"] .section-title,
html[lang="zh"] .shelf-card .title { font-family: var(--font-display-zh); }
html[lang="zh"] .deck { font-family: var(--font-serif-zh); font-style: normal; }

.section-intro, .lede { overflow-wrap: anywhere; }

/* ---------- Tables ---------- */
.table-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; margin: 20px 0 8px; }
.data-table { width: 100%; border-collapse: collapse; font-size: 15px; line-height: 1.5; }
.data-table th {
  font-family: var(--font-label);
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-3);
  text-align: left;
  font-weight: 400;
  padding: 10px 14px 10px 0;
  border-bottom: var(--stroke) solid var(--ink);
  vertical-align: bottom;
}
.data-table td {
  padding: 11px 14px 11px 0;
  border-bottom: 1px solid var(--ink);
  vertical-align: top;
}
.data-table td.num { font-family: var(--font-display-en); font-weight: 700; white-space: nowrap; }
.data-table .muted { color: var(--ink-2); }

/* ---------- Tier blocks (strategy) ---------- */
.tier { border-top: var(--stroke) solid var(--ink); padding: 26px 0 8px; margin: 40px 0 0; }
.tier-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 8px 24px; }
.tier-head .section-title { margin: 0; }
.tier-est {
  font-family: var(--font-label);
  font-size: 14px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--coral);
}
.topic { padding: 22px 0 6px; border-bottom: 1px solid var(--ink); }
.topic:last-child { border-bottom: 0; }
.topic h3 { font-size: 24px; margin: 0 0 8px; }
html[lang="zh"] .topic h3 { font-family: var(--font-display-zh); }
.topic .est { font-family: var(--font-label); letter-spacing: 0.14em; font-size: 13px; color: var(--ink-3); margin: 0 0 8px; }
.topic p { font-size: 17px; max-width: 44em; }
.topic .go { font-family: var(--font-label); letter-spacing: 0.16em; font-size: 13px; text-transform: uppercase; }

.note {
  border: var(--stroke) solid var(--ink);
  background: var(--cream-2);
  padding: 18px 22px;
  margin: 28px 0;
  max-width: 48em;
}
.note p { font-size: 16px; margin: 0 0 8px; }
.note p:last-child { margin: 0; }
.note .label { display: block; font-family: var(--font-label); font-size: 12px; letter-spacing: 0.2em; color: var(--coral); margin: 0 0 8px; }

/* ---------- Lab hub ---------- */
.steps-row { list-style: none; margin: 24px 0 0; padding: 0; display: flex; flex-wrap: wrap; gap: 10px; }
.steps-row li {
  border: 1.5px solid var(--ink);
  padding: 8px 14px;
  font-size: 15px;
  background: var(--cream);
}
.steps-row li b { font-family: var(--font-label); font-weight: 400; letter-spacing: 0.1em; color: var(--coral); margin-right: 6px; }

.meter { height: 10px; border: 1.5px solid var(--ink); background: var(--cream); margin: 14px 0 6px; }
.meter i { display: block; height: 100%; width: 0; background: var(--coral); }
.meter-text { font-family: var(--font-label); font-size: 13px; letter-spacing: 0.14em; color: var(--ink-2); margin: 0; }

.mod-card .qlist { list-style: none; margin: 10px 0 0; padding: 0; font-size: 14px; color: var(--ink-2); line-height: 1.55; }
.mod-card .qlist li { padding: 3px 0; border-top: 1px dotted var(--ink-3); }
.mod-card .qlist .qid { font-family: var(--font-label); letter-spacing: 0.08em; color: var(--ink); margin-right: 6px; }

.progress-panel { border: var(--stroke) solid var(--ink); padding: 22px 26px; margin: 32px 0 0; }
.progress-panel .figure { font-family: var(--font-display-en); font-weight: 800; font-size: 40px; line-height: 1; margin: 0 0 4px; }

/* ---------- Past-paper matrix ---------- */
.matrix { border-collapse: collapse; font-size: 13px; min-width: 860px; width: 100%; }
.matrix th, .matrix td { border: 1px solid var(--ink); padding: 5px 6px; text-align: center; }
.matrix thead th {
  font-family: var(--font-label);
  font-weight: 400;
  font-size: 13px;
  letter-spacing: 0.06em;
  background: var(--cream-2);
}
.matrix th.topic-name { text-align: left; font-family: var(--font-body-en); font-weight: 500; font-size: 13px; white-space: nowrap; background: var(--cream); }
.matrix th.topic-name a { text-decoration: none; }
.matrix td.c0 { color: var(--ink-3); }
.matrix td.c1 { background: #F3DDD2; }
.matrix td.c2 { background: #EDB9A7; }
.matrix td.c3 { background: #E8614C; color: var(--cream); font-weight: 700; }
.matrix td.tot, .matrix th.tot { font-weight: 700; background: var(--cream-2); }
.matrix tr.part-row th {
  text-align: left;
  font-family: var(--font-label);
  font-weight: 400;
  letter-spacing: 0.18em;
  font-size: 12px;
  color: var(--coral);
  background: var(--cream);
}
.legend-row { display: flex; flex-wrap: wrap; gap: 8px 18px; font-size: 14px; color: var(--ink-2); margin: 10px 0 0; }
.legend-row .sw { display: inline-block; width: 14px; height: 14px; border: 1px solid var(--ink); vertical-align: -2px; margin-right: 6px; }

.topic-list { list-style: none; margin: 18px 0 0; padding: 0; }
.topic-list > li { padding: 18px 0; border-bottom: 1px solid var(--ink); }
.topic-list > li:first-child { border-top: var(--stroke) solid var(--ink); }
.topic-list h3 { font-size: 22px; margin: 0 0 4px; }
html[lang="zh"] .topic-list h3 { font-family: var(--font-display-zh); }
.topic-list .count { font-family: var(--font-label); font-size: 13px; letter-spacing: 0.16em; color: var(--ink-3); margin: 0 0 10px; }
.qids { display: flex; flex-wrap: wrap; gap: 6px; margin: 0; padding: 0; list-style: none; }
.qids li { font-size: 13px; line-height: 1; padding: 6px 8px; border: 1px solid var(--ink-3); white-space: nowrap; }
.qids li.lab { border: 1.5px solid var(--coral); padding: 0; }
.qids li.lab a { display: block; padding: 5px 7px; text-decoration: none; color: var(--ink); }
.qids li.lab a:hover { background: var(--coral); color: var(--cream); }
.qids li.lab .sw-mark { font-family: var(--font-label); letter-spacing: 0.08em; color: var(--coral); margin-left: 5px; }
.qids li.lab a:hover .sw-mark { color: var(--cream); }

/* ---------- Reading list ---------- */
.shelf--two { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 880px) { .shelf--two { grid-template-columns: 1fr; } }
.shelf-card .title { overflow-wrap: anywhere; }

/* ---------- Layout fixes on top of the shared sheet ---------- */
/* site.css resets .masthead-inner padding to 0 on the sides, which overrides .shell;
   restore the gutter so the masthead lines up with the page content. */
.masthead .shell.masthead-inner { padding-left: 48px; padding-right: 48px; }
@media (max-width: 720px) { .masthead .shell.masthead-inner { padding-left: 24px; padding-right: 24px; } }

.shell > .section-title { margin-top: 48px; }
.shell > .rule-thick + .section-title,
.shell > .eyebrow + .section-title { margin-top: 0; }
.tier-head { margin-bottom: 14px; }

.topic .table-scroll { max-width: 760px; }
.topic .data-table { table-layout: fixed; }
.topic .data-table th:nth-child(1) { width: 18%; }
.topic .data-table th:nth-child(2) { width: 52%; }
.topic .data-table th:nth-child(3) { width: 30%; }

.mod-card .qlist .qid { font-family: var(--font-body-en); font-weight: 600; font-size: 13px; letter-spacing: 0; font-variant-numeric: tabular-nums; }
.steps-row li.lead { border: 0; padding-left: 0; padding-right: 0; background: transparent; color: var(--ink-2); }
.topic .go { display: inline-block; margin: 0 18px 8px 0; line-height: 1.5; }
@media (max-width: 560px) { .brand { flex-wrap: wrap; row-gap: 6px; } }
.data-table.cmp td:first-child { white-space: nowrap; font-weight: 600; }

/* =========================================================================
   Competition ladder (hub + overview)
   ========================================================================= */
.ladder { display: grid; grid-template-columns: 3fr 2fr; gap: 0 48px; margin: 28px 0 0; }
@media (max-width: 880px) { .ladder { grid-template-columns: 1fr; gap: 36px; } }
.strand-title { font-family: var(--font-label); font-size: 13px; letter-spacing: 0.2em; text-transform: uppercase; color: var(--coral); margin: 0 0 12px; }
.rungs { list-style: none; margin: 0; padding: 0; }
.rung + .rung::before {
  content: ""; display: block; width: 0; height: 22px;
  border-left: var(--stroke) solid var(--ink); margin-left: 28px;
}
.rung.rung--gap::before { border-left-style: dashed; border-left-width: 1.5px; }
.node {
  display: block; border: var(--stroke) solid var(--ink); background: var(--cream);
  padding: 12px 16px; text-decoration: none; color: var(--ink);
}
a.node:hover, .node a.node-title:hover { background: var(--cream-2); }
.node .yr { display: block; font-family: var(--font-label); font-size: 12px; letter-spacing: 0.16em; text-transform: uppercase; color: var(--ink-3); margin: 0 0 4px; }
.node .nm { display: block; font-family: var(--font-display-en); font-weight: 700; font-size: 19px; line-height: 1.25; }
html[lang="zh"] .node .nm { font-family: var(--font-display-zh); }
.node .ds { display: block; font-size: 14px; line-height: 1.45; color: var(--ink-2); margin-top: 4px; }
.node .go { display: block; font-family: var(--font-label); font-size: 12px; letter-spacing: 0.16em; text-transform: uppercase; color: var(--coral); margin-top: 6px; }
.node--plain { border-width: 1.5px; border-color: var(--ink-3); color: var(--ink-2); }
.node--goal { background: var(--ink); color: var(--cream); border-color: var(--ink); }
.node--goal .yr, .node--goal .ds { color: var(--cream-2); }
.node--split { padding: 0; }
.node--split .node-title { display: block; padding: 12px 16px 10px; text-decoration: none; color: var(--ink); }
.node .subs { display: grid; grid-template-columns: 1fr 1fr; border-top: 1.5px solid var(--ink); }
.node .subs a { display: block; padding: 10px 16px 12px; text-decoration: none; color: var(--ink); font-size: 15px; line-height: 1.4; }
.node .subs a + a { border-left: 1.5px solid var(--ink); }
.node .subs a:hover { background: var(--coral); color: var(--cream); }
.node .subs b { display: block; font-family: var(--font-display-en); font-size: 16px; }
.ladder-key { display: flex; flex-wrap: wrap; gap: 8px 24px; font-size: 14px; color: var(--ink-2); margin: 20px 0 0; }
.ladder-key .k { display: inline-block; width: 0; height: 18px; border-left: var(--stroke) solid var(--ink); vertical-align: -4px; margin-right: 8px; }
.ladder-key .k--gap { border-left: 1.5px dashed var(--ink); }

/* Bank / tool cards */
.bank-meta { font-family: var(--font-label); font-size: 13px; letter-spacing: 0.12em; color: var(--ink-2); margin: 10px 0 0; }
.bank-meta b { font-family: var(--font-display-en); font-weight: 700; letter-spacing: 0; color: var(--ink); }
.shelf-card.is-primary { border-color: var(--coral); }
.shelf-card .tag { display: inline-block; font-family: var(--font-label); font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase; border: 1.5px solid var(--coral); color: var(--coral); padding: 3px 7px 2px; margin: 0 0 10px; }
.shelf--four { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 880px) { .shelf--four { grid-template-columns: 1fr; } }
.facts { display: grid; grid-template-columns: max-content 1fr; gap: 0; margin: 20px 0 8px; max-width: 48em; border-top: var(--stroke) solid var(--ink); }
.facts dt, .facts dd { margin: 0; padding: 10px 16px 10px 0; border-bottom: 1px solid var(--ink); font-size: 16px; line-height: 1.5; }
.facts dt { font-family: var(--font-label); font-size: 12px; letter-spacing: 0.16em; text-transform: uppercase; color: var(--ink-3); padding-top: 13px; }
@media (max-width: 560px) {
  .facts { grid-template-columns: 1fr; }
  .facts dt { border-bottom: 0; padding-bottom: 0; }
}
.plain-list { font-size: 17px; line-height: 1.6; max-width: 44em; padding-left: 1.2em; }
.plain-list li { margin: 0 0 8px; }

/* Lab hubs: a module still in preparation (no link), and the "BPhO family" link in the IPC / SPC / BAAO mastheads */
.mod-card.is-soon { border-style: dashed; border-color: var(--ink-3); color: var(--ink-2); }
.mod-card.is-soon:hover { background: transparent; }
.mod-card.is-soon .label { color: var(--ink-3); }
.masthead .nav a.nav-family { color: var(--coral); }