/* Elite PM shared chrome: tokens, top bar, rail items and "On this page". Dark by default. */
:root {
  --hx-bg: #1c1c1c;
  --hx-surface: #222221;
  --hx-raised: #2b2a29;
  --hx-line: #343331;
  --hx-line-strong: #4a4845;
  --hx-text: #ecebe8;
  --hx-title: #ffffff;
  --hx-soft: #cfccc6;
  --hx-muted: #a29e97;
  --hx-accent: #e27d60;
  --hx-accent-soft: #33241f;
  --hx-top: 64px;
  --hx-rail: 300px;
  --hx-serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --hx-sans: "Inter", "Avenir Next", "Segoe UI", system-ui, -apple-system, sans-serif;
  color-scheme: dark;
}

:root[data-theme="light"] {
  --hx-bg: #fafaf9;
  --hx-surface: #ffffff;
  --hx-raised: #f0efec;
  --hx-line: #e4e2dd;
  --hx-line-strong: #cfccc6;
  --hx-text: #1c1b19;
  --hx-title: #111110;
  --hx-soft: #44423e;
  --hx-muted: #6f6c66;
  --hx-accent: #c2553b;
  --hx-accent-soft: #f8ebe6;
  color-scheme: light;
}

html { background: var(--hx-bg); }

/* ---------- Top bar ---------- */
.hx-top {
  position: sticky;
  top: 0;
  z-index: 130;
  display: flex;
  align-items: center;
  gap: 20px;
  height: var(--hx-top);
  padding: 0 24px;
  color: var(--hx-text);
  background: var(--hx-bg);
  border-bottom: 1px solid var(--hx-line);
  font-family: var(--hx-sans);
}
.hx-slot-start:empty { display: none; }
.hx-brand {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 12px;
  width: calc(var(--hx-rail) - 32px);
  color: var(--hx-text);
  font: 600 1.15rem/1 var(--hx-serif);
  text-decoration: none;
  white-space: nowrap;
}
.hx-mark { color: var(--hx-accent); font: 400 1.6rem/1 var(--hx-sans); }

.hx-search {
  display: flex;
  flex: 0 1 220px;
  align-items: center;
  gap: 8px;
  min-width: 0;
  height: 40px;
  padding: 0 8px 0 12px;
  color: var(--hx-muted);
  background: var(--hx-surface);
  border: 1px solid var(--hx-line);
  border-radius: 10px;
  cursor: text;
}
.hx-search:focus-within { border-color: var(--hx-muted); }
.hx-search svg { flex: 0 0 16px; width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; }
.hx-search input {
  flex: 1;
  min-width: 0;
  padding: 0;
  color: var(--hx-text);
  background: transparent;
  border: 0;
  outline: 0;
  font: 500 .9rem/1 var(--hx-sans);
}
.hx-search input::placeholder { color: var(--hx-muted); }
.hx-search input::-webkit-search-cancel-button { display: none; }
.hx-search kbd { padding: 3px 6px; color: var(--hx-muted); border: 1px solid var(--hx-line); border-radius: 6px; font: 600 .7rem/1 var(--hx-sans); }

.hx-tabs { display: flex; flex: 1; align-self: stretch; gap: 4px; min-width: 0; }
.hx-tabs a {
  display: flex;
  align-items: center;
  padding: 0 12px;
  color: var(--hx-muted);
  border-bottom: 2px solid transparent;
  font: 500 .95rem/1 var(--hx-sans);
  text-decoration: none;
  white-space: nowrap;
}
.hx-tabs a:hover { color: var(--hx-text); }
.hx-tabs a[aria-current="page"] { color: var(--hx-text); border-bottom-color: var(--hx-text); }

.hx-slot-end { display: flex; flex: 0 0 auto; gap: 14px; align-items: center; margin-left: auto; }
.hx-top .hx-slot-end > a,
.hx-top .hx-slot-end > button:not(.hx-theme) {
  display: inline-flex;
  align-items: center;
  min-height: 38px;
  padding: 0 18px;
  color: var(--hx-bg);
  background: var(--hx-text);
  border: 1px solid var(--hx-text);
  border-radius: 999px;
  box-shadow: none;
  font: 600 .88rem/1 var(--hx-sans);
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
}
.hx-top .hx-slot-end > [hidden] { display: none !important; }
.hx-top .hx-slot-end > .is-complete,
.hx-top .hx-slot-end > [aria-pressed="true"] { color: var(--hx-text); background: transparent; border-color: var(--hx-line); }

.hx-top .hx-theme {
  position: relative;
  flex: 0 0 auto;
  width: 52px;
  height: 28px;
  padding: 0;
  background: var(--hx-raised);
  border: 1px solid var(--hx-line);
  border-radius: 999px;
  cursor: pointer;
}
.hx-theme span {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  background: var(--hx-text);
  border-radius: 50%;
  transform: translateX(24px);
  box-shadow: inset -6px -3px 0 0 var(--hx-raised);
  transition: transform .2s ease;
}
:root[data-theme="light"] .hx-theme span { transform: none; box-shadow: none; }

.hx-top .hx-menu {
  display: none;
  place-items: center;
  width: 40px;
  height: 40px;
  padding: 0;
  color: var(--hx-text);
  background: var(--hx-surface);
  border: 1px solid var(--hx-line);
  border-radius: 8px;
  cursor: pointer;
}

/* ---------- Shared rail + "On this page" look ---------- */
/* Every track's left rail: scrolls on its own, shows a thin scrollbar, never drags the page. */
#researchRail,
#courseRail,
#masteryRail {
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  scrollbar-color: var(--hx-line-strong) transparent;
}
.hx-page {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 230px;
  gap: 56px;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 48px;
}
.hx-page:has(> .hx-toc[hidden]) { grid-template-columns: minmax(0, 1fr); }
.hx-article { min-width: 0; }
.hx-rail-title { margin: 0 0 10px; padding: 0 2px; color: var(--hx-text); font: 650 1.05rem/1.3 var(--hx-sans); }
.hx-rail-item {
  display: block;
  padding: 11px 16px;
  color: var(--hx-soft);
  border-radius: 10px;
  font: 500 .95rem/1.45 var(--hx-sans);
  text-decoration: none;
}
.hx-rail-item:hover { background: var(--hx-raised); }
.hx-rail-item[aria-current="page"] { color: var(--hx-accent); background: var(--hx-raised); }
/* Rail items set their own display, which would override the [hidden] used by search filtering. */
a[hidden],
button[hidden] { display: none !important; }
.hx-no-match::before { content: "No matches"; display: block; padding: 12px 16px; color: var(--hx-muted); font: 500 .9rem/1.4 var(--hx-sans); }

.hx-toc {
  position: sticky;
  top: calc(var(--hx-top) + 24px);
  align-self: start;
  max-height: calc(100vh - var(--hx-top) - 48px);
  padding: 40px 0 24px 20px;
  overflow-y: auto;
  border-left: 1px solid var(--hx-line);
  font-family: var(--hx-sans);
}
.hx-toc[hidden] { display: none !important; }
.hx-toc-title { margin: 0 0 12px; color: var(--hx-text); font: 650 1rem/1.3 var(--hx-sans); letter-spacing: 0; text-transform: none; }
.hx-toc nav { display: grid; gap: 2px; }
.hx-toc nav a { padding: 7px 0; color: var(--hx-muted); font: 500 .92rem/1.4 var(--hx-sans); text-decoration: none; }
.hx-toc nav a:hover,
.hx-toc nav a.active { color: var(--hx-accent); }

/* Tablet landscape: the brand stops reserving rail width so tabs and actions fit on one row. */
@media (max-width: 1240px) {
  .hx-brand { width: auto; }
}

@media (max-width: 1180px) {
  .hx-tabs a { padding: 0 8px; }
  .hx-page { grid-template-columns: minmax(0, 1fr); gap: 0; padding: 0 36px; }
  .hx-toc { order: -1; }
  .hx-toc {
    position: static;
    max-height: none;
    padding: 20px 0 0;
    border-left: 0;
  }
  .hx-toc-title { display: none; }
  .hx-toc nav { display: flex; gap: 6px; overflow-x: auto; scrollbar-width: none; }
  .hx-toc nav a { flex: 0 0 auto; padding: 6px 12px; border: 1px solid var(--hx-line); border-radius: 999px; font-size: .82rem; }
}

/* Narrow screens: the track tabs drop to a scrollable second row so every page can switch tracks. */
@media (max-width: 1060px) {
  :root { --hx-top: 108px; }
  .hx-top { flex-wrap: wrap; align-content: flex-start; row-gap: 0; padding-top: 12px; }
  .hx-tabs {
    order: 5;
    flex: 0 0 calc(100% + 48px);
    height: 44px;
    margin: 12px -24px 0;
    padding: 0 16px;
    overflow-x: auto;
    border-top: 1px solid var(--hx-line);
    scrollbar-width: none;
  }
  .hx-tabs::-webkit-scrollbar { display: none; }
  .hx-search { flex: 1 1 auto; max-width: 320px; }
  .hx-brand { width: auto; }
}

@media (max-width: 900px) {
  :root { --hx-top: 102px; }
  .hx-top { gap: 10px; padding: 9px 14px 0; }
  .hx-tabs { flex-basis: calc(100% + 28px); margin: 9px -14px 0; padding: 0 6px; }
  .hx-top .hx-menu { display: grid; }
  .hx-search { display: none; }
  .hx-page { padding: 0 18px; }
}

@media (max-width: 560px) {
  .hx-brand { font-size: 0; gap: 0; }
  .hx-tabs { padding: 0 2px; }
  .hx-tabs a { padding: 0 7px; font-size: .84rem; }
  .hx-slot-end { gap: 8px; }
  .hx-top .hx-slot-end > a,
  .hx-top .hx-slot-end > button:not(.hx-theme) { min-height: 36px; padding: 0 12px; font-size: .78rem; }
  .hx-top .hx-theme { width: 44px; }
  .hx-theme span { transform: translateX(16px); }
}

@media (prefers-reduced-motion: reduce) {
  .hx-theme span { transition: none; }
}