/* ── learn ──
 * /learn's graph: the canvas and composer a lone graph fills the note with, its card
 * among other blocks, the reading view and the "ask about this" tooltip. Theme tokens
 * only, so it follows all 13 themes. Linked from index.html in cascade order. */

:root {
  --sb-cgraph: #94e2d5;
  /* One colour per branch (learnBranchSlot). The first is the theme's accent; the rest are
     fixed hues pulled toward --fg, which lightens them on dark themes and darkens them on
     light ones, so all six stay readable on all 13 themes. */
  --lrn-b1: var(--accent);
  --lrn-b2: color-mix(in oklab, #3fb6d6 72%, var(--fg));
  --lrn-b3: color-mix(in oklab, #e5953d 72%, var(--fg));
  --lrn-b4: color-mix(in oklab, #e0609e 72%, var(--fg));
  --lrn-b5: color-mix(in oklab, #6b8cf5 72%, var(--fg));
  --lrn-b6: color-mix(in oklab, #c9b23c 72%, var(--fg));
}

/* These set their own display, which beats the `hidden` attribute's; say it again. */
.lrn-read[hidden], .lrn-empty[hidden], .lrn-tip[hidden] { display: none; }

/* A lone graph IS the document (the .pdf-only arrangement). */
#document-container.cgraph-only { padding: 0; overflow: hidden; display: flex; flex-direction: column; }
#document-container.cgraph-only > .cgraph-block { flex: 1; min-height: 0; display: flex; flex-direction: column; max-width: none; margin: 0; padding: 0; }
#document-container.cgraph-only .lrn-card,
#document-container.cgraph-only .gutter,
#document-container.cgraph-only .touch-tools { display: none; }
.lrn-host { display: none; }
#document-container.cgraph-only .lrn-host { display: grid; grid-template-rows: minmax(0, 1fr) auto; flex: 1; min-height: 0; }
.lrn-note { margin: auto; padding: 24px; color: var(--fg-dim); font-size: 12.5px; text-align: center; }
.lrn-note button { background: none; border: 1px solid var(--border); color: var(--fg); border-radius: 5px; padding: 2px 10px; cursor: pointer; font: inherit; }

/* The card a graph is among other blocks. */
.lrn-card { display: flex; align-items: center; gap: 14px; max-width: 560px; padding: 10px 14px; margin: 4px 0;
  border: 1px solid var(--border); border-radius: 6px; background: var(--bg-raised); cursor: pointer; }
.lrn-card:hover, .lrn-card:focus-visible { border-color: var(--accent-line); }
.lrn-card-ico { color: var(--sb-cgraph); font-size: 1.4em; line-height: 1; }
.lrn-card-meta { display: flex; flex-direction: column; min-width: 0; gap: 2px; }
.lrn-card-name { color: var(--fg); font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.lrn-card-sub { color: var(--fg-dim); font-size: 0.88em; }
.lrn-card-open { margin-left: auto; color: var(--accent); font-size: 0.88em; flex: none; }

/* Canvas */
.lrn-mid { position: relative; min-height: 0; }
.lrn-canvas { position: absolute; inset: 0; overflow: auto;
  background-image: radial-gradient(color-mix(in srgb, var(--fg-faint) 55%, transparent) 1px, transparent 1.2px);
  background-size: 22px 22px; }
.lrn-sizer { position: relative; }
.lrn-world { position: absolute; left: 0; top: 0; transform-origin: 0 0; }
.lrn-empty { position: absolute; inset: 0; display: grid; place-items: center; text-align: center; color: var(--fg-dim); pointer-events: none; padding: 24px; }
.lrn-empty-ico { font-size: 34px; color: var(--accent); opacity: .55; line-height: 1; margin-bottom: 14px; }
.lrn-empty-h { color: var(--fg); font-weight: 600; margin-bottom: 6px; }
.lrn-empty p { font-size: 12.5px; line-height: 1.7; }
svg.lrn-edges { position: absolute; left: 0; top: 0; overflow: visible; pointer-events: none; }
.lrn-edge { fill: none; stroke: var(--accent-line); stroke-width: 1.5; }
.lrn-edge.plain { stroke: var(--fg-faint); stroke-dasharray: 3 4; }
.lrn-dot { fill: var(--accent); }
.lrn-dot.plain { fill: var(--fg-faint); }

.lrn-node { position: absolute; display: flex; flex-direction: column; background: var(--bg-raised); border: 1px solid var(--border);
  border-radius: 6px; overflow: hidden; transition: border-color .15s, box-shadow .15s; font-size: 12px; }
.lrn-node:hover { border-color: color-mix(in srgb, var(--accent) 22%, var(--border)); }
.lrn-node.cur { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.lrn-node.born { animation: lrnIn .26s ease-out; }
.lrn-node.hit { animation: lrnHit 1.8s ease-out 2; }
@keyframes lrnIn { from { opacity: 0; transform: scale(.95); } to { opacity: 1; transform: none; } }
@keyframes lrnHit { 0%, 100% { box-shadow: 0 0 0 0 var(--accent-soft); } 30% { box-shadow: 0 0 0 7px var(--accent-line); } }
.lrn-q { padding: 7px 10px; border-bottom: 1px solid var(--border-soft); font-weight: 600; display: flex; gap: 8px; cursor: pointer; color: var(--fg); }
.lrn-q:hover .lrn-qt { color: var(--accent); }
.lrn-n { color: var(--fg-faint); font-weight: 400; flex: none; }
.lrn-from { padding: 5px 10px 0; font-size: 11px; color: var(--fg-dim); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.lrn-from b { color: var(--accent); font-weight: 400; font-style: italic; }
.lrn-a { flex: 1; overflow: auto; padding: 6px 10px 8px; white-space: pre-wrap; line-height: 1.55; color: var(--fg); overscroll-behavior: contain; cursor: text; }
.lrn-a::selection, .lrn-a *::selection, .lrn-read-a::selection, .lrn-read-a *::selection { background: var(--accent-line); color: var(--fg); }
/* A branch's phrase: an underline in its own colour (--bc, set per mark), never a link —
   the line stays selectable, so other words on it can be asked about too. */
mark.lrn-mark { --bc: var(--accent); background: color-mix(in srgb, var(--bc) 9%, transparent); color: var(--fg);
  border-bottom: 2px solid var(--bc); border-radius: 2px 2px 0 0; transition: background .18s ease; }
mark.lrn-mark.lit { background: color-mix(in srgb, var(--bc) 24%, transparent); }
mark.lrn-mark.pend { background: transparent; border: 1px dashed var(--accent); }
.lrn-err { color: var(--danger, #e06c75); }
.lrn-f { display: flex; justify-content: space-between; align-items: center; padding: 3px 4px 3px 10px; border-top: 1px solid var(--border-soft); font-size: 11px; color: var(--fg-dim); }
.lrn-btn { background: none; border: 0; color: var(--fg-dim); cursor: pointer; padding: 1px 6px; border-radius: 4px; font: inherit; font-size: 11.5px; }
.lrn-btn:hover { color: var(--fg); background: var(--accent-soft); }
.lrn-btn.x { opacity: 0; }
.lrn-node:hover .lrn-btn.x, .lrn-node:focus-within .lrn-btn.x { opacity: 1; }
.lrn-btn.x:hover { color: var(--danger, #e06c75); background: color-mix(in srgb, var(--danger, #e06c75) 15%, transparent); }
.lrn-caret { display: inline-block; width: 7px; height: 1.05em; background: var(--accent); vertical-align: text-bottom; margin-left: 1px; animation: lrnBlink 1s steps(1) infinite; }
@keyframes lrnBlink { 50% { opacity: 0; } }
.lrn-zoom { position: absolute; right: 14px; bottom: 12px; display: flex; align-items: center; background: var(--bg-raised); border: 1px solid var(--border); border-radius: 6px; font-size: 11.5px; }
.lrn-zoom button { background: none; border: 0; padding: 3px 9px; cursor: pointer; color: var(--fg-dim); font: inherit; }
.lrn-zoom button:hover { color: var(--fg); }
.lrn-zoom-pct { color: var(--fg-faint); min-width: 4.5ch; text-align: center; font-variant-numeric: tabular-nums; }

/* Composer — byebyechat's input dock */
.lrn-dock { border-top: 1px solid var(--border); background: var(--bg-page); }
.lrn-ctx { display: flex; align-items: center; gap: 8px; padding: 6px 24px; background: var(--accent-soft); border-bottom: 1px solid var(--border-soft); font-size: 11.5px; min-width: 0; }
.lrn-ctx .lbl { color: var(--fg-dim); flex: none; }
.lrn-ctx .txt { color: var(--accent); font-style: italic; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: 1; min-width: 0; }
.lrn-ctx button { background: none; border: 0; color: var(--fg-dim); cursor: pointer; font: inherit; padding: 0 4px; }
.lrn-ctx button:hover { color: var(--fg); }
.lrn-row { display: flex; gap: 10px; align-items: flex-end; padding: 12px 24px; max-width: 880px; margin: 0 auto; width: 100%; }
.lrn-slash { color: var(--accent); align-self: center; }
.lrn-input { flex: 1; min-width: 0; resize: none; min-height: 38px; max-height: 120px; padding: 8px 12px; background: var(--bg-raised);
  border: 1px solid var(--border); border-radius: 6px; color: var(--fg); font: inherit; line-height: 1.5; }
.lrn-input:focus { outline: none; border-color: var(--accent-line); box-shadow: 0 0 0 1px var(--accent-soft); }
.lrn-input::placeholder { color: var(--fg-faint); }
.lrn-send { padding: 8px 16px; border: 0; border-radius: 6px; background: var(--accent); color: var(--bg-page); font: inherit; font-weight: 600; cursor: pointer; white-space: nowrap; }
.lrn-send:disabled { opacity: .35; cursor: default; }
.lrn-done { padding: 12px 24px; text-align: center; font-size: 12px; color: var(--fg-dim); }
.lrn-done b { color: var(--accent); font-weight: 500; }
/* Which model answers (or "add key"), between the box and send — the canvas's small text button. */
.lrn-modelbtn { align-self: center; max-width: 220px; overflow: hidden; text-overflow: ellipsis; }

/* "✦ ask about this" — byebyechat's pill */
.lrn-tip { position: fixed; z-index: 130; background: var(--accent); color: var(--bg-page); font: inherit; font-size: 12px; font-weight: 600;
  padding: 7px 12px; border-radius: 6px; cursor: pointer; border: 0; box-shadow: 0 10px 30px rgba(0,0,0,.35); animation: lrnTip .14s ease-out; }
.lrn-tip::after { content: ''; position: absolute; left: 50%; bottom: -5px; transform: translateX(-50%); border: 5px solid transparent; border-bottom-width: 0; border-top-color: var(--accent); }
.lrn-tip.ro { background: var(--bg-raised); color: var(--fg-dim); border: 1px solid var(--border); cursor: default; }
.lrn-tip.ro::after { border-top-color: var(--border); }
@keyframes lrnTip { from { opacity: 0; transform: translateY(3px) scale(.94); } to { opacity: 1; transform: none; } }

/* The reading view: grows out of its card */
.lrn-read { position: fixed; inset: 0; z-index: 95; overflow: auto; display: flex; justify-content: center; align-items: flex-start; padding: 64px 24px 48px; }
.lrn-read-back { position: fixed; inset: 0; background: color-mix(in srgb, var(--bg-page) 64%, transparent); backdrop-filter: blur(3px); opacity: 0; transition: opacity .26s ease; }
.lrn-read.open .lrn-read-back { opacity: 1; }
.lrn-read-pane { position: relative; background: var(--bg-raised); border: 1px solid var(--border); border-radius: 10px;
  box-shadow: 0 24px 60px rgba(0,0,0,.4), 0 0 0 1px var(--accent-soft); transform-origin: 0 0; }
.lrn-read-pane::before { content: attr(data-title); position: absolute; top: -9px; left: 22px; padding: 0 9px; background: var(--bg-raised);
  color: var(--accent); font-size: 12px; font-weight: 600; letter-spacing: .5px; opacity: 0; transition: opacity .18s ease .14s; }
.lrn-read.open .lrn-read-pane::before { opacity: 1; }
.lrn-read-inner { padding: 26px 36px 32px; opacity: 0; transform: translateY(4px); transition: opacity .2s ease .13s, transform .26s ease .13s; }
.lrn-read.open .lrn-read-inner { opacity: 1; transform: none; }
.lrn-read-x { position: absolute; top: 10px; right: 10px; background: none; border: 0; color: var(--fg-faint); cursor: pointer; font: inherit; font-size: 11.5px; padding: 3px 8px; border-radius: 4px; }
.lrn-read-x:hover { color: var(--fg); background: var(--accent-soft); }
.lrn-read-crumbs { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; font-size: 11px; color: var(--fg-faint); margin-bottom: 18px; padding-right: 60px; }
.lrn-read-crumbs button { background: none; border: 0; color: var(--fg-dim); cursor: pointer; font: inherit; padding: 0; }
.lrn-read-crumbs button:hover { color: var(--fg); }
.lrn-read-crumbs .cur { color: var(--accent); }
.lrn-read-from { font-size: 11.5px; color: var(--fg-dim); margin-bottom: 6px; }
.lrn-read-from b { color: var(--accent); font-weight: 400; font-style: italic; }
.lrn-read-q { font-size: 18px; font-weight: 700; line-height: 1.35; margin-bottom: 16px; text-wrap: balance; color: var(--fg); }
.lrn-read-a { font-size: 14px; line-height: 1.8; color: var(--fg); white-space: pre-wrap; cursor: text; }
.lrn-read-br { margin-top: 26px; padding-top: 14px; border-top: 1px solid var(--border-soft); display: flex; flex-direction: column; align-items: flex-start; gap: 6px; }
.lrn-read-br .lbl { font-size: 10.5px; letter-spacing: .14em; text-transform: uppercase; color: var(--fg-faint); }
.lrn-chip { background: var(--bg-code); border: 1px solid var(--border); border-radius: 6px; padding: 6px 10px; cursor: pointer; color: var(--fg-dim); font: inherit; font-size: 12px; text-align: left; max-width: 100%; }
.lrn-chip:hover { border-color: var(--accent-line); color: var(--fg); }
.lrn-hint { font-size: 11px; color: var(--fg-faint); }

/* Reading width: wide by default, ⇔ cycles it. The text reflows to the measure as the pane eases. */
.lrn-read-pane { width: min(1100px, 100%); }   /* the width change is eased in script (cycleLearnReadWidth) */
.lrn-read-pane[data-width="comfortable"] { width: min(860px, 100%); }
.lrn-read-pane[data-width="full"] { width: min(1400px, 100%); }
.lrn-read-a { max-width: 100ch; }
.lrn-read-pane[data-width="comfortable"] .lrn-read-a { max-width: 72ch; }
.lrn-read-pane[data-width="full"] .lrn-read-a { max-width: none; }
.lrn-read-tools { position: absolute; top: 10px; right: 10px; display: flex; gap: 2px; z-index: 1; }
.lrn-read-tools .lrn-read-x { position: static; }
.lrn-read-w b { color: var(--accent); font-weight: 500; }
.lrn-read-crumbs { padding-right: 170px; }
.lrn-read-up { background: none; border: 0; color: var(--fg-faint); cursor: pointer; font: inherit; font-size: 11px; padding: 0 0 0 8px; }
.lrn-read-up:hover { color: var(--accent); }

/* The way into a branch: a small graph icon after its phrase, in the branch's colour. */
.lrn-bicon { --bc: var(--accent); display: inline-grid; place-items: center; width: 22px; height: 18px; margin: 0 2px 0 5px; padding: 0;
  vertical-align: -3px; border: 1px solid color-mix(in srgb, var(--bc) 45%, transparent); border-radius: 5px; background: var(--bg-code);
  color: var(--bc); cursor: pointer; transition: background .18s ease, color .18s ease, border-color .18s ease, transform .2s cubic-bezier(.2,.85,.25,1); }
.lrn-bicon svg { width: 13px; height: 13px; display: block; }
.lrn-bicon:hover, .lrn-bicon:focus-visible { background: var(--bc); color: var(--bg-raised); border-color: var(--bc); transform: translateY(-1px); }
.lrn-bicon:focus-visible { outline: 2px solid var(--bc); outline-offset: 2px; }

/* Hovering an icon previews the branch before you go. */
.lrn-peek { --bc: var(--accent); position: fixed; z-index: 120; width: 340px; max-width: calc(100vw - 24px); background: var(--bg-code);
  border: 1px solid color-mix(in srgb, var(--bc) 50%, transparent); border-radius: 8px; padding: 10px 12px; font-size: 12px; color: var(--fg);
  box-shadow: 0 16px 40px -16px rgba(0,0,0,.5); pointer-events: none; opacity: 0; transform: translateY(4px) scale(.98);
  transition: opacity .16s ease, transform .2s cubic-bezier(.2,.85,.25,1); }
.lrn-peek.on { opacity: 1; transform: none; }
.lrn-peek .k { color: var(--bc); font-size: 10.5px; letter-spacing: .1em; text-transform: uppercase; margin-bottom: 4px; }
.lrn-peek .t { font-weight: 600; margin-bottom: 4px; }
.lrn-peek .x { color: var(--fg-dim); display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.lrn-peek .h { margin-top: 6px; color: var(--fg-faint); font-size: 11px; }

@media (max-width: 700px) {
  .lrn-row { padding: 10px 76px 10px 14px; }
  .lrn-ctx, .lrn-done { padding-left: 14px; padding-right: 14px; }
  .lrn-read { padding: 40px 10px 24px; }
  .lrn-read-inner { padding: 22px 18px 24px; }
  .lrn-read-crumbs { padding-right: 0; margin-top: 18px; }
}
@media (prefers-reduced-motion: reduce) {
  .lrn-node.born, .lrn-node.hit, .lrn-tip, .lrn-caret { animation: none; }
  .lrn-read-back, .lrn-read-inner, .lrn-read-pane::before, .lrn-read-pane, .lrn-bicon, .lrn-peek, mark.lrn-mark { transition: none; }
}