/* Frontier Prep — study site styles */
:root {
  --bg: #0f1216;
  --bg-elev: #171b21;
  --bg-elev2: #1e242c;
  --border: #2a313b;
  --text: #d7dee7;
  --text-dim: #97a2b0;
  --text-mute: #6b7683;
  --accent: #e8853b;      /* warm anthropic-ish orange */
  --accent-2: #5aa7ff;
  --green: #3fb950;
  --code-bg: #11151a;
  --radius: 8px;
  --sidebar-w: 320px;
  --content-max: 860px;
  --mono: ui-monospace, "Cascadia Code", "JetBrains Mono", Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.6;
}
#app { display: flex; min-height: 100vh; }

/* ---------- Sidebar ---------- */
#sidebar {
  width: var(--sidebar-w);
  flex: 0 0 var(--sidebar-w);
  background: var(--bg-elev);
  border-right: 1px solid var(--border);
  height: 100vh;
  position: sticky;
  top: 0;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}
.brand { padding: 18px 18px 12px; border-bottom: 1px solid var(--border); }
.brand-title { font-size: 18px; font-weight: 700; letter-spacing: .2px; }
.brand-sub { font-size: 12px; color: var(--text-dim); margin-top: 3px; }

#nav { padding: 8px 0 8px; flex: 1; }
.nav-section { margin: 2px 0 6px; }
.nav-section-head {
  display: flex; align-items: center; gap: 7px;
  padding: 9px 14px 4px; cursor: pointer; user-select: none;
}
.nav-section-head:hover { background: var(--bg-elev2); }
.nav-section-head .chev { flex: 0 0 auto; width: 10px; font-size: 10px; color: var(--text-mute); }
.nav-section.collapsed .nav-items,
.nav-section.collapsed .nav-blurb { display: none; }
.nav-section.collapsed .nav-section-head { padding-bottom: 9px; }
.nav-section-title {
  font-size: 12px; font-weight: 700; text-transform: uppercase;
  letter-spacing: .6px; color: var(--text-dim); flex: 1;
}
.ring { flex: 0 0 auto; font-size: 11px; color: var(--text-mute); font-variant-numeric: tabular-nums; }
.lab-badge {
  font-size: 9.5px; font-weight: 700; letter-spacing: .4px;
  padding: 1px 6px; border-radius: 999px; text-transform: uppercase;
  border: 1px solid transparent; white-space: nowrap;
}
.lab-anthropic { color: #f0a868; border-color: #6a4a2a; background: #2a1e12; }
.lab-openai { color: #7fd0c0; border-color: #2c5049; background: #10201d; }
.lab-both { color: var(--text-mute); border-color: var(--border); background: transparent; }

.nav-blurb { font-size: 11.5px; color: var(--text-mute); padding: 0 16px 4px; line-height: 1.4; }
.nav-items { list-style: none; margin: 2px 0 4px; padding: 0; }
.nav-item {
  display: flex; align-items: center; gap: 9px;
  padding: 6px 16px 6px 18px; font-size: 13.5px; color: var(--text-dim);
  cursor: pointer; border-left: 2px solid transparent; text-decoration: none;
}
.nav-item:hover { background: var(--bg-elev2); color: var(--text); }
.nav-item.active { background: var(--bg-elev2); color: var(--text); border-left-color: var(--accent); }
.nav-item .tick {
  flex: 0 0 16px; width: 16px; height: 16px; border-radius: 50%;
  border: 1.5px solid var(--text-mute); display: inline-flex;
  align-items: center; justify-content: center; font-size: 10px; color: transparent;
}
.nav-item.done .tick { background: var(--green); border-color: var(--green); color: #0b1f12; }
.nav-item .item-title { flex: 1; }
.nav-item .type-chip {
  font-size: 9px; text-transform: uppercase; letter-spacing: .4px;
  color: var(--text-mute); border: 1px solid var(--border); border-radius: 4px; padding: 0 4px;
}
.sidebar-foot { padding: 12px 16px; font-size: 11px; color: var(--text-mute); border-top: 1px solid var(--border); }

/* ---------- Content ---------- */
#content { flex: 1; min-width: 0; height: 100vh; overflow-y: auto; }
#content-inner { max-width: var(--content-max); margin: 0 auto; padding: 40px 48px 120px; }
.muted { color: var(--text-mute); }

.crumb { font-size: 12px; color: var(--text-mute); margin-bottom: 8px; }
.crumb .lab-badge { margin-left: 6px; }

.item-actions {
  display: flex; flex-wrap: wrap; gap: 10px; align-items: center;
  margin: 18px 0 26px; padding-bottom: 18px; border-bottom: 1px solid var(--border);
}
.btn {
  font-family: var(--sans); font-size: 13px; font-weight: 600;
  padding: 7px 13px; border-radius: var(--radius); border: 1px solid var(--border);
  background: var(--bg-elev2); color: var(--text); cursor: pointer; text-decoration: none;
  display: inline-flex; align-items: center; gap: 7px;
}
.btn:hover { border-color: var(--text-mute); }
.btn-primary { background: var(--accent); border-color: var(--accent); color: #1a1206; }
.btn-primary:hover { filter: brightness(1.05); }
.btn.done-toggle.is-done { background: #14311d; border-color: var(--green); color: var(--green); }

.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 48px; padding-top: 20px; border-top: 1px solid var(--border); }
.pager a { color: var(--text-dim); text-decoration: none; font-size: 13px; max-width: 46%; }
.pager a:hover { color: var(--text); }
.pager .next { text-align: right; margin-left: auto; }

/* ---------- Markdown ---------- */
.md h1, .md h2, .md h3, .md h4 { line-height: 1.25; font-weight: 700; }
.md h1 { font-size: 28px; margin: 0 0 16px; }
.md h2 { font-size: 21px; margin: 34px 0 12px; padding-bottom: 6px; border-bottom: 1px solid var(--border); }
.md h3 { font-size: 17px; margin: 24px 0 8px; }
.md h4 { font-size: 15px; margin: 18px 0 6px; color: var(--text-dim); }
.md p { margin: 10px 0; }
.md a { color: var(--accent-2); text-decoration: none; }
.md a:hover { text-decoration: underline; }
.md strong { color: #fff; font-weight: 700; }
.md em { font-style: italic; }
.md ul, .md ol { margin: 10px 0; padding-left: 24px; }
.md li { margin: 4px 0; }
.md li.task { list-style: none; margin-left: -22px; }
.md li.task .box { display: inline-block; width: 15px; }
.md blockquote {
  margin: 12px 0; padding: 6px 16px; border-left: 3px solid var(--accent);
  background: var(--bg-elev); color: var(--text-dim); border-radius: 0 var(--radius) var(--radius) 0;
}
.md blockquote p { margin: 4px 0; }
.md hr { border: none; border-top: 1px solid var(--border); margin: 26px 0; }
.md code {
  font-family: var(--mono); font-size: 12.5px;
  background: var(--code-bg); border: 1px solid var(--border);
  padding: 1px 5px; border-radius: 5px; color: #e6c07b;
}
.md pre {
  background: var(--code-bg); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 14px 16px; overflow-x: auto; margin: 14px 0;
}
.md pre code { background: none; border: none; padding: 0; color: var(--text); font-size: 12.5px; line-height: 1.5; }

/* tables scroll inside their own container */
.table-wrap { overflow-x: auto; margin: 14px 0; }
.md table { border-collapse: collapse; width: 100%; font-size: 13.5px; }
.md th, .md td { border: 1px solid var(--border); padding: 7px 11px; text-align: left; vertical-align: top; }
.md th { background: var(--bg-elev2); font-weight: 700; }
.md tbody tr:nth-child(even), .md tr:nth-child(even) td { background: rgba(255,255,255,0.015); }

/* reveal widgets on problem pages */
details.reveal { margin: 14px 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg-elev); }
details.reveal > summary {
  cursor: pointer; padding: 10px 14px; font-weight: 600; font-size: 13.5px;
  list-style: none; user-select: none; display: flex; align-items: center; gap: 8px;
}
details.reveal > summary::-webkit-details-marker { display: none; }
details.reveal > summary::before { content: "▸"; color: var(--text-mute); }
details.reveal[open] > summary::before { content: "▾"; }
details.reveal[open] > summary { border-bottom: 1px solid var(--border); }
details.reveal .reveal-body { padding: 4px 14px 12px; }
details.reveal pre { margin: 10px 0 4px; }

/* ---------- responsive ---------- */
#menu-toggle {
  display: none; position: fixed; top: 12px; left: 12px; z-index: 20;
  background: var(--bg-elev2); color: var(--text); border: 1px solid var(--border);
  border-radius: 6px; font-size: 18px; width: 38px; height: 38px; cursor: pointer;
}
@media (max-width: 820px) {
  #menu-toggle { display: block; }
  #sidebar {
    position: fixed; z-index: 15; left: 0; top: 0; transform: translateX(-100%);
    transition: transform .2s ease; box-shadow: 2px 0 18px rgba(0,0,0,.5);
  }
  #sidebar.open { transform: translateX(0); }
  #content-inner { padding: 64px 20px 100px; }
}