/* Mathe-Abi — Design-System (DLG-2026-06-18-Z01)
   "modernes Schulbuch": warmes Papier, Indigo, Amber-Akzent. Responsiv ohne UA-Sniffing. */

:root {
  --paper:      #fbfaf5;
  --paper-2:    #f4f1e8;
  --ink:        #1f2330;
  --ink-soft:   #4b5169;
  --indigo:     #29335c;
  --indigo-2:   #3a5a9c;
  --accent:     #d98324;   /* Amber — interaktive Elemente */
  --accent-soft:#f6e7cf;
  --line:       #e3ddcd;
  --good:       #2f7d4f;
  --warn:       #b06a00;
  --gap:        #c98a3a;
  --maxw:       46rem;
  --sidebar:    18rem;
  --radius:     12px;
  --shadow:     0 1px 2px rgba(31,35,48,.06), 0 8px 24px rgba(31,35,48,.06);
  --serif:      "Iowan Old Style", "Palatino Linotype", "Charter", Georgia, "Times New Roman", serif;
  --sans:       -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 1.0625rem/1.7 var(--serif);
  -webkit-text-size-adjust: 100%; text-rendering: optimizeLegibility;
}

/* ---------- Topbar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; flex-wrap: wrap; gap: .5rem .6rem;
  padding: .6rem 1rem; background: rgba(251,250,245,.9); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line); font-family: var(--sans);
}
.topbar .brand { font-weight: 700; color: var(--indigo); letter-spacing: -.01em; }
.topbar .brand b { color: var(--accent); }
.topbar .spacer { flex: 1; }
.topbar a.navlink, .topbar button {
  font: 600 .85rem/1 var(--sans); color: var(--indigo); background: transparent;
  border: 1px solid var(--line); border-radius: 999px; padding: .45rem .8rem; cursor: pointer;
  text-decoration: none; white-space: nowrap;
}
.topbar a.navlink.active { background: var(--indigo); color: #fff; border-color: var(--indigo); }
.topbar button:hover, .topbar a.navlink:hover { border-color: var(--accent); color: var(--accent); }
.menu-toggle { display: none; }

/* ---------- Layout ---------- */
.shell { display: grid; grid-template-columns: var(--sidebar) 1fr; gap: 0; max-width: 78rem; margin: 0 auto; }
.sidebar {
  position: sticky; top: 3.2rem; align-self: start; height: calc(100vh - 3.2rem);
  overflow-y: auto; padding: 1.4rem 1rem 3rem; border-right: 1px solid var(--line);
  font-family: var(--sans);
}
.sidebar h3 { font-size: .72rem; text-transform: uppercase; letter-spacing: .08em; color: var(--ink-soft); margin: 1.2rem 0 .4rem; }
.toc { list-style: none; margin: 0; padding: 0; }
.toc li { margin: .1rem 0; }
.toc a { display: block; padding: .32rem .6rem; border-radius: 8px; color: var(--ink-soft);
  text-decoration: none; font-size: .9rem; line-height: 1.35; border-left: 2px solid transparent; }
.toc a:hover { background: var(--paper-2); color: var(--indigo); }
.toc a.active { background: var(--accent-soft); color: var(--indigo); border-left-color: var(--accent); font-weight: 600; }

main { padding: 2rem clamp(1rem, 4vw, 3rem) 6rem; min-width: 0; }
.content { max-width: var(--maxw); }

/* ---------- Typo ---------- */
h1 { font: 700 clamp(1.8rem, 1.2rem + 2vw, 2.5rem)/1.15 var(--sans); color: var(--indigo); letter-spacing: -.02em; margin: .2rem 0 .4rem; }
.lede { color: var(--ink-soft); font-size: 1.1rem; }
.content h2 { font: 700 1.4rem/1.25 var(--sans); color: var(--indigo); letter-spacing: -.01em; }
.content h3 { font: 700 1.12rem/1.3 var(--sans); color: var(--indigo-2); margin-top: 1.6rem; }
p, li { overflow-wrap: break-word; }
a { color: var(--indigo-2); text-decoration-color: var(--accent); text-underline-offset: 2px; }
strong { color: var(--ink); }
hr { border: none; border-top: 1px solid var(--line); margin: 2rem 0; }

/* ---------- Collapsible level-2 sections ---------- */
section.level2 { border-top: 1px solid var(--line); margin-top: 1.2rem; }
section.level2 > h2 {
  cursor: pointer; user-select: none; display: flex; align-items: center; gap: .6rem;
  margin: 0; padding: 1rem 0 .8rem;
}
section.level2 > h2::before {
  content: ""; flex: none; width: .62rem; height: .62rem; border-right: 2.5px solid var(--accent);
  border-bottom: 2.5px solid var(--accent); transform: rotate(45deg); transition: transform .18s ease; margin-top: -.2rem;
}
section.level2.collapsed > h2::before { transform: rotate(-45deg); }
section.level2.collapsed > :not(h2) { display: none; }
section.level2 > h2:hover { color: var(--accent); }

/* ---------- Detail-Kaskade (<details>) — Tiefe sichtbar ---------- */
details { margin: .8rem 0; border-left: 3px solid var(--accent); background: var(--paper-2);
  border-radius: 0 var(--radius) var(--radius) 0; padding: 0 1rem; }
details > summary { cursor: pointer; font-family: var(--sans); font-weight: 600; color: var(--indigo);
  padding: .7rem 0; list-style: none; }
details > summary::-webkit-details-marker { display: none; }
details > summary::before { content: "▸ "; color: var(--accent); }
details[open] > summary::before { content: "▾ "; }
details[open] { padding-bottom: .8rem; }
details details { border-left-color: var(--indigo-2); background: #fff; }
details details details { border-left-color: var(--gap); }

/* ---------- Blockquote / callout ---------- */
blockquote { margin: 1.2rem 0; padding: .8rem 1.1rem; background: #fff; border: 1px solid var(--line);
  border-left: 4px solid var(--indigo-2); border-radius: 0 var(--radius) var(--radius) 0; color: var(--ink-soft); }
blockquote p { margin: .3rem 0; }

/* ---------- Tables ---------- */
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; margin: 1.2rem 0; }
table { border-collapse: collapse; width: 100%; font-size: .95rem; font-family: var(--sans); }
th, td { border: 1px solid var(--line); padding: .5rem .7rem; text-align: left; vertical-align: top; }
th { background: var(--paper-2); color: var(--indigo); font-weight: 700; }
tr:nth-child(even) td { background: #fdfcf8; }

/* ---------- Code ---------- */
code { font: .9em/1.5 ui-monospace, "SF Mono", Menlo, Consolas, monospace; background: var(--paper-2);
  padding: .1rem .35rem; border-radius: 6px; }
pre { background: #1f2330; color: #f4f1e8; padding: 1rem 1.1rem; border-radius: var(--radius); overflow-x: auto; }
pre code { background: transparent; color: inherit; padding: 0; }

/* ---------- Konfidenz-/Relevanz-Tags ---------- */
.tag { display: inline-block; font: 600 .72rem/1 var(--sans); padding: .25rem .5rem; border-radius: 999px; }
.tag-ok { background: #e4f2ea; color: var(--good); }
.tag-warn { background: #f7ecd6; color: var(--warn); }

/* ---------- Cards (Landing) ---------- */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); gap: 1rem; margin: 1.6rem 0; }
.card { display: block; padding: 1.2rem 1.3rem; background: #fff; border: 1px solid var(--line);
  border-radius: var(--radius); box-shadow: var(--shadow); text-decoration: none; color: inherit; transition: transform .15s, border-color .15s; }
.card:hover { transform: translateY(-2px); border-color: var(--accent); }
.card h3 { margin: 0 0 .3rem; color: var(--indigo); font-family: var(--sans); }
.card p { margin: 0; color: var(--ink-soft); font-size: .95rem; }
.card .arrow { color: var(--accent); font-weight: 700; }

.meta-row { display: flex; flex-wrap: wrap; gap: .5rem; margin: 1rem 0; font-family: var(--sans); font-size: .82rem; color: var(--ink-soft); }
.meta-row span { background: var(--paper-2); border: 1px solid var(--line); border-radius: 999px; padding: .3rem .7rem; }

footer.site { font-family: var(--sans); font-size: .82rem; color: var(--ink-soft); border-top: 1px solid var(--line);
  margin-top: 3rem; padding-top: 1rem; }

/* ---------- KaTeX-Skalierung (kein Overflow / keine Verzerrung) ---------- */
.katex { font-size: 1.05em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: .3rem 0; }
.katex-display > .katex { white-space: nowrap; }

/* ---------- JSXGraph-Diagramme ---------- */
.jxgbox { margin: 1.4rem 0; border: 1px solid var(--line); border-radius: var(--radius);
  background: #fff; box-shadow: var(--shadow); touch-action: pan-y; }

/* ---------- Topbar: Vorlesen-Stub ---------- */
.topbar .readaloud { color: var(--accent); border-color: var(--accent); }
.topbar .readaloud:hover { background: var(--accent); color: #fff; }
.toast { position: fixed; left: 50%; bottom: 1.6rem; transform: translate(-50%, 1rem);
  z-index: 80; background: var(--indigo); color: #fff; font-family: var(--sans); font-size: .9rem;
  padding: .7rem 1.1rem; border-radius: 999px; box-shadow: var(--shadow);
  opacity: 0; transition: opacity .25s ease, transform .25s ease; pointer-events: none; }
.toast.show { opacity: 1; transform: translate(-50%, 0); }

/* ---------- Sidebar: Kapitelbaum (Inhaltsseiten) ---------- */
.tree-home { display: block; font-family: var(--sans); font-weight: 600; font-size: .92rem;
  color: var(--indigo); text-decoration: none; padding: .35rem .6rem; border-radius: 8px; margin-bottom: .4rem; }
.tree-home:hover { background: var(--paper-2); }
ul.tree { list-style: none; margin: 0 0 .6rem; padding: 0; }
ul.tree li { margin: .1rem 0; }
ul.tree a.tree-link { display: block; padding: .32rem .6rem; border-radius: 8px; color: var(--ink-soft);
  text-decoration: none; font-size: .9rem; line-height: 1.35; border-left: 2px solid transparent; }
ul.tree a.tree-link:hover { background: var(--paper-2); color: var(--indigo); }
ul.tree a.tree-link.active { background: var(--accent-soft); color: var(--indigo);
  border-left-color: var(--accent); font-weight: 600; }
.tree-test { font-family: var(--sans); font-size: .62rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .05em; color: var(--warn); background: #f7ecd6; border-radius: 999px; padding: .1rem .35rem; }

/* ---------- Startseite: Feedback-Loop, Lernpfade, Kapitel-Übersicht ---------- */
ol.loop { padding-left: 1.2rem; }
ol.loop > li { margin: .5rem 0; }
.btn-primary { display: inline-block; font-family: var(--sans); font-weight: 700; font-size: .95rem;
  background: var(--accent); color: #fff; text-decoration: none; padding: .6rem 1.1rem; border-radius: 999px;
  box-shadow: var(--shadow); transition: transform .15s, background .15s; }
.btn-primary:hover { transform: translateY(-1px); background: #c2740f; }
.card.path-pruefung { border-top: 3px solid var(--accent); }
.card.path-verstehen { border-top: 3px solid var(--indigo-2); }
.muted { color: var(--ink-soft); font-size: .95rem; }
.tree-overview { display: grid; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); gap: 1rem; margin: 1.2rem 0; }
.tree-group { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 1rem 1.2rem; box-shadow: var(--shadow); }
.tree-group h3 { margin: 0 0 .5rem; font-family: var(--sans); color: var(--indigo); font-size: 1rem; }
.tree-group ul { list-style: none; margin: 0; padding: 0; font-family: var(--sans); font-size: .92rem; }
.tree-group li { margin: .25rem 0; }
.tree-group a { color: var(--indigo-2); text-decoration: none; }
.tree-group a:hover { text-decoration: underline; text-decoration-color: var(--accent); }

/* ---------- Mobile ---------- */
.backdrop { display: none; }
@media (max-width: 56rem) {
  .shell { grid-template-columns: 1fr; }
  .menu-toggle { display: inline-flex; align-items: center; }
  .sidebar {
    position: fixed; top: 0; left: 0; z-index: 60; height: 100vh; width: min(82vw, 20rem);
    background: var(--paper); transform: translateX(-100%); transition: transform .22s ease;
    box-shadow: var(--shadow); padding-top: 1rem;
  }
  body.nav-open .sidebar { transform: translateX(0); }
  body.nav-open .backdrop { display: block; position: fixed; inset: 0; z-index: 50; background: rgba(31,35,48,.4); }
  main { padding: 1.2rem 1.1rem 5rem; }
  .content { max-width: 100%; }
  section.level2 > h2 { padding: .9rem 0 .7rem; }
  /* Topbar einzeilig halten: Spec-Navlinks auf dem Handy ausblenden (Start = Marke,
     Bau-Charter/Design-Spec über die Karten der Startseite erreichbar). */
  .topbar a.navlink { display: none; }
  .topbar { gap: .45rem; padding: .5rem .8rem; }
  .topbar .readaloud, .topbar #collapse-all, .topbar #expand-all { padding: .4rem .6rem; font-size: .8rem; }
}
@media (min-width: 56.01rem) { .menu-toggle, .backdrop { display: none; } }