:root {
  --bg: #faf6ee; --panel: #f3ede0; --text: #24211c; --muted: #6b645a;
  --line: #ddd4c2; --bad: #a33b2a; --bad-soft: #f6e4df; --accent: #8250df; --accent-soft: #efe7fb; --code-bg: #f1ebdd;
  --serif: Georgia, "Iowan Old Style", "Palatino Linotype", "Times New Roman", serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, "DejaVu Sans Mono", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #1b1a17; --panel: #24221e; --text: #e8e2d4; --muted: #a39b8b;
    --line: #3a372f; --bad: #e69683; --bad-soft: #3a2723; --accent: #a371f7; --accent-soft: #2d2250; --code-bg: #25231f; }
}
* { box-sizing: border-box; }
html { touch-action: manipulation; scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 17px/1.65 var(--sans); overflow-wrap: anywhere; }
h1, h2, h3 { font-family: var(--serif); font-weight: 600; line-height: 1.25; }
h1 { font-size: 2rem; margin: 0 0 .5rem; }
h2 { font-size: 1.3rem; margin: 2.2rem 0 .6rem; }
h3 { font-size: 1.05rem; margin: 0 0 .4rem; }
a { color: var(--accent); }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; border-radius: 3px; }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 8px; top: 8px; background: var(--bg); padding: .4rem .7rem; z-index: 10; }

.top { border-bottom: 1px solid var(--line); background: var(--bg); position: sticky; top: 0; z-index: 5; }
.top-inner { max-width: 86rem; margin: 0 auto; padding: .7rem 16px; display: flex; align-items: center; gap: 1rem; }
.brand { font-family: var(--serif); font-size: 1.2rem; color: var(--text); text-decoration: none; font-weight: 600; }
.progress { margin-left: auto; color: var(--muted); font-size: .9rem; }
.menu-btn { display: none; }
button, .btn { font: inherit; font-size: .9rem; background: transparent; color: var(--text); border: 1px solid var(--line);
  padding: .35rem .8rem; border-radius: 4px; cursor: pointer; transition: background .15s, border-color .15s; }
button:hover, .btn:hover { background: var(--panel); border-color: var(--muted); }

.layout { max-width: 86rem; margin: 0 auto; padding: 0 16px; display: grid; grid-template-columns: 15rem minmax(0, 1fr); gap: 2.5rem; }
.nav { padding: 1.5rem 0; font-size: .95rem; position: sticky; top: 3.4rem; align-self: start; max-height: calc(100vh - 4rem); overflow: auto; }
.nav h2 { font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); font-family: var(--sans); margin: 1.4rem 0 .4rem; }
.nav h2:first-child { margin-top: 0; }
.nav ul { list-style: none; margin: 0; padding: 0; }
.nav a { display: flex; gap: .5rem; padding: .25rem .5rem; text-decoration: none; color: var(--text); border-left: 2px solid transparent; }
.nav a:hover { background: var(--panel); }
.nav a[aria-current="page"] { border-left-color: var(--accent); color: var(--accent); font-weight: 600; }
.nav .num { color: var(--muted); font-family: var(--mono); min-width: 1.6rem; }
.nav .tick { margin-left: auto; color: var(--accent); white-space: nowrap; flex-shrink: 0; font-size: .75rem; padding-left: .4rem; }

main { padding: 2rem 0 3rem; max-width: 42rem; min-width: 0; outline: none; }
.kicker { color: var(--muted); font-size: .85rem; text-transform: uppercase; letter-spacing: .06em; margin: 0; }
.lede { color: var(--muted); font-size: 1.05rem; }
section { margin: 0 0 1.6rem; }
p { margin: .5rem 0; }
pre, code { font-family: var(--mono); font-size: .9rem; }
code { background: var(--code-bg); padding: .08rem .3rem; border-radius: 3px; }
pre { background: var(--code-bg); border: 1px solid var(--line); border-radius: 4px; padding: 1rem; overflow-x: auto; line-height: 1.5; margin: .6rem 0; max-width: 100%; }
pre code { background: none; padding: 0; }
.example { display: grid; gap: .3rem; border-left: 3px solid var(--accent); padding: .3rem 0 .3rem 1rem; margin: .8rem 0; }
.example div { font-family: var(--mono); font-size: .9rem; }
.example span { color: var(--muted); font-family: var(--sans); font-size: .8rem; display: block; }
.predict { background: var(--accent-soft); padding: .9rem 1.1rem; border-radius: 4px; }
.predict p { margin: .2rem 0; }
.row { display: flex; flex-wrap: wrap; gap: .6rem; align-items: center; }
details { border-top: 1px solid var(--line); padding: .5rem 0; }
details:last-of-type { border-bottom: 1px solid var(--line); }
summary { cursor: pointer; padding: .2rem 0; }
.locked { color: var(--muted); font-style: italic; }
.done { display: flex; align-items: center; gap: .6rem; padding: .8rem 0; border-top: 1px solid var(--line); margin-top: 2rem; }
.done input { width: 1.2rem; height: 1.2rem; accent-color: var(--accent); }
dl.words { display: grid; grid-template-columns: max-content 1fr; gap: .2rem 1.2rem; margin: .4rem 0; }
dl.words dt { font-weight: 600; } dl.words dd { margin: 0; }
.pager { display: flex; justify-content: space-between; gap: 1rem; margin-top: 2rem; }
.foot { max-width: 86rem; margin: 0 auto; padding: 1.5rem 16px 3rem; border-top: 1px solid var(--line); color: var(--muted); font-size: .9rem; display: flex; gap: .6rem; flex-wrap: wrap; }
.note { color: var(--muted); font-size: .9rem; }


main.ex { max-width: none; display: grid; gap: 0 2.5rem; grid-template-columns: minmax(0, 1fr);
  grid-template-areas: "top" "bench" "bottom"; }
.a-top { grid-area: top; max-width: 40rem; } .a-bottom { grid-area: bottom; max-width: 40rem; } .a-bench { grid-area: bench; min-width: 0; }
@media (min-width: 1180px) {
  main.ex { grid-template-columns: minmax(0, 34rem) minmax(0, 1fr); grid-template-areas: "top bench" "bottom bench"; align-items: start; }
  .a-bench { position: sticky; top: 4rem; max-height: calc(100vh - 5rem); overflow: auto; padding-right: .4rem; align-self: start; grid-row: 1 / span 2; }
}
.a-bench h2 { margin-top: .2rem; } .a-bench h3 { margin-top: 1.4rem; }
.bar { height: .6rem; background: var(--panel); border: 1px solid var(--line); border-radius: 4px; overflow: hidden; margin: 1rem 0 .4rem; }
.bar div { height: 100%; background: var(--accent); transition: width .3s; }
.btn.primary, button.primary { background: var(--accent); color: var(--bg); border-color: var(--accent); text-decoration: none; }
.btn.primary:hover, button.primary:hover { background: var(--accent); filter: brightness(1.1); }
button:disabled { opacity: .6; cursor: progress; }
.btn { display: inline-block; text-decoration: none; color: var(--text); }
.row.spaced { margin-top: 2rem; } .tools { margin-bottom: .6rem; }
.py-status { margin: 0 0 .6rem; } .py-status[data-state="failed"] { color: var(--bad); }

.editor { display: flex; border: 1px solid var(--line); border-radius: 4px; background: var(--code-bg); height: 21rem; overflow: hidden; margin: .4rem 0; }
.editor:focus-within { outline: 3px solid var(--accent); outline-offset: 1px; }
.gutter, .hl, .ta, .snip { font-family: var(--mono); font-size: 14px; line-height: 21px; tab-size: 4; }
.gutter { padding: 10px 8px; text-align: right; color: var(--muted); overflow: hidden; user-select: none; min-width: 2.6rem; border-right: 1px solid var(--line); }
.gutter .err { background: var(--bad); color: var(--bg); border-radius: 2px; }
.ed-body { position: relative; flex: 1; min-width: 0; }
.hl, .ta { position: absolute; inset: 0; margin: 0; padding: 10px 12px; border: 0; white-space: pre; overflow: auto; background: transparent; }
.hl { pointer-events: none; overflow: hidden; color: var(--text); border-radius: 0; }
.hl code { font: inherit; background: none; padding: 0; }
.ta { color: transparent; caret-color: var(--text); resize: none; outline: none; }
.ta::selection { background: var(--accent-soft); color: transparent; }
.t-c { color: var(--muted); font-style: italic; } .t-s { color: #3b7a57; } .t-k { color: var(--accent); font-weight: 600; } .t-n { color: #9a5b13; }
@media (prefers-color-scheme: dark) { .t-s { color: #8fcfa6; } .t-n { color: #e0b070; } }
.snip { width: 100%; background: var(--code-bg); color: var(--text); border: 1px solid var(--line); border-radius: 4px; padding: 8px 10px; resize: vertical; }
.out { margin: .6rem 0; }
.result { padding: .7rem 1rem; border-radius: 4px; border: 1px solid var(--line); margin: .5rem 0; }
.result.good { background: var(--accent-soft); border-color: var(--accent); }
.result.bad { background: var(--bad-soft); border-color: var(--bad); }
.result pre { margin: .4rem 0 0; background: transparent; border: 0; padding: 0; white-space: pre-wrap; }
.passnote { border-left: 3px solid var(--accent); padding-left: 1rem; margin: .8rem 0; }
.checks { list-style: none; padding: 0; margin: .6rem 0; }
.checks li { padding: .3rem 0; border-bottom: 1px solid var(--line); }
.checks code { background: none; padding: 0; font-size: .82rem; }
.checks summary { cursor: pointer; display: flex; gap: .6rem; align-items: baseline; flex-wrap: wrap; }
.checks details { border: 0; padding: 0; }
.tag { font-size: .7rem; text-transform: uppercase; letter-spacing: .06em; padding: .05rem .4rem; border-radius: 3px; margin-right: .6rem; border: 1px solid var(--accent); color: var(--accent); }
.fail .tag { border-color: var(--bad); color: var(--bad); }
.gx { display: grid; gap: .2rem; padding: .6rem 0 .2rem 1rem; }
.gx span { color: var(--muted); font-size: .8rem; } .gx code { white-space: pre-wrap; word-break: break-all; }

.viz { margin: .8rem 0; padding: 0; } .viz figcaption { color: var(--muted); font-size: .85rem; margin-bottom: .4rem; }
.big { font: 600 1.6rem var(--mono); padding: .4rem 0; }
.arrow { color: var(--muted); margin: .2rem 0; }
.vrow { display: grid; grid-template-columns: 6rem minmax(0, 1fr) 3.4rem; gap: .6rem; align-items: center; font-family: var(--mono); font-size: .82rem; padding: 2px 0; }
.vlab { color: var(--muted); text-align: right; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.vtrack { background: var(--panel); height: .9rem; border-radius: 2px; }
.vbar { height: 100%; background: var(--accent); border-radius: 2px; transition: width .25s; } .vbar.neg { background: var(--bad); }
.vnum { text-align: right; }
.scroll { overflow-x: auto; max-width: 100%; }
.vgrid { border-collapse: collapse; font-family: var(--mono); font-size: .82rem; }
.vgrid th, .vgrid td { border: 1px solid var(--line); padding: .25rem .55rem; text-align: center; min-width: 2.4rem; }
.vgrid th { color: var(--muted); font-weight: 400; background: var(--panel); }
.chips { display: flex; flex-wrap: wrap; gap: .4rem; }
.chip { font-family: var(--mono); font-size: .85rem; border: 1px solid var(--line); border-radius: 4px; padding: .15rem .5rem; background: var(--panel); }
.chip i { color: var(--muted); font-size: .7rem; margin-right: .4rem; font-style: normal; }

@media (max-width: 800px) {
  body { font-size: 16px; }
  h1 { font-size: 1.6rem; }
  .menu-btn { display: inline-block; }
  .layout { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .nav { display: none; position: static; max-height: none; border-bottom: 1px solid var(--line); }
  .nav.open { display: block; }
  .progress { margin-left: auto; }
  .top-inner { gap: .6rem; }
  .brand { font-size: 1.05rem; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } * { transition: none !important; } }
main:focus-visible { outline: none; }
.lang { font: inherit; font-size: .85rem; background: var(--bg); color: var(--text); border: 1px solid var(--line); border-radius: 4px; padding: .3rem .4rem; max-width: 9rem; }
.brand { display: inline-flex; align-items: center; gap: .6rem; }
.brand img { display: block; border-radius: 5px; }
.langs { display: flex; gap: .25rem; margin-left: auto; }
.langbtn { padding: .25rem .5rem; font-size: .8rem; min-width: 2.2rem; }
.langbtn[aria-pressed="true"] { background: var(--accent); color: var(--bg); border-color: var(--accent); }
.progress { margin-left: .5rem; white-space: nowrap; }
@media (max-width: 800px) { .top-inner { flex-wrap: wrap; } .langs { order: 3; width: 100%; margin-left: 0; } .progress { margin-left: auto; } }
.top { transition: transform .2s; }
body.hdr-off .top { transform: translateY(-100%); }
.top:focus-within { transform: none; }
body.hdr-off .nav { top: 1rem; max-height: calc(100vh - 2rem); }
@media (min-width: 1180px) { body.hdr-off .a-bench { top: 1rem; max-height: calc(100vh - 2rem); } }

/* compact header */
.top-inner { padding: .3rem 16px; gap: .6rem; }
.brand img { width: 32px; height: 32px; }
.langbtn { padding: .15rem .4rem; font-size: .75rem; min-width: 1.9rem; }
.menu-btn { padding: .2rem .55rem; font-size: .8rem; }
.progress { font-size: .8rem; margin-left: .3rem; }
.nav { top: 3rem; }
@media (max-width: 800px) {
  .top-inner { flex-wrap: nowrap; gap: .4rem; }
  .langs { order: 0; width: auto; margin-left: auto; gap: .15rem; }
  .progress { margin-left: 0; }
  .langbtn { min-width: 1.7rem; padding: .15rem .3rem; }
}
/* illustration above the footer */
.foot-art { margin-top: 2.5rem; padding: 0 16px; }
.foot-art img { display: block; margin: 0 auto; width: 100%; max-width: 34rem; height: auto; }