/* DOMVYBE — courses, lessons and practice labs.
   Built on the dark-glass tokens in studio.css. The page stays monochrome; the only colour on
   the site lives inside code, where it does a job: telling a string from a keyword at a glance. */

:root{
  --t-com:#8a9099; --t-str:#9fc08a; --t-num:#d7ba7d; --t-key:#a7a2e6; --t-tag:#8fb8d8;
  --t-att:#c9b98e; --t-prop:#8fb8d8; --t-at:#a7a2e6; --t-fn:#8fd4d0;
  --ok:#7fc79a; --no:#e0806f;
  --code-bg:#0c0d10;
}

/* ---------------------------------------------------------------- course index */
.courses{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.course{position:relative;display:flex;flex-direction:column;gap:14px;padding:30px 28px 26px;border-radius:26px;
  border:1px solid var(--line);background:rgba(255,255,255,.035);box-shadow:inset 0 1px 0 rgba(255,255,255,.07);
  overflow:hidden;isolation:isolate;transition:transform .5s var(--ease),border-color .4s,background .4s}
.course::after{content:"";position:absolute;inset:auto -30% -70% -30%;height:110%;z-index:-1;pointer-events:none;
  background:radial-gradient(closest-side,rgba(255,255,255,.09),transparent);opacity:0;transform:translateY(24%);
  transition:opacity .6s,transform .8s var(--ease)}
.course:hover{transform:translateY(-4px);border-color:var(--line-2);background:rgba(255,255,255,.055)}
.course:hover::after{opacity:1;transform:none}
.course .no{font:500 12px/1 var(--mono);letter-spacing:.18em;color:var(--soft)}
.course h3{font-size:clamp(28px,2.6vw,38px);line-height:1;color:var(--hi)}
.course .sub{font-size:14.5px;color:var(--muted);text-wrap:pretty;flex:1}
/* not `.meta`: pages.css claims that name for the glass panels, and the learn card only
   wants a label row under a rule. */
.course .course-foot{display:flex;justify-content:space-between;align-items:center;gap:12px;padding-top:16px;border-top:1px solid var(--line)}
.course .course-foot .mono{color:var(--soft)}
.course .go{width:38px;height:38px;border-radius:12px;display:grid;place-items:center;font-size:16px;color:var(--muted);
  border:1px solid var(--line);background:rgba(255,255,255,.04);transition:transform .5s var(--ease),color .3s,background .3s}
.course:hover .go{color:var(--accent-ink);background:var(--accent);border-color:transparent;transform:translate(3px,-3px)}
.course .langs{display:flex;gap:6px;flex-wrap:wrap}
.tagx{font:500 10.5px/1 var(--mono);letter-spacing:.14em;text-transform:uppercase;color:var(--label);
  padding:6px 9px;border-radius:8px;border:1px solid var(--line);background:rgba(255,255,255,.03)}

/* a thin ring showing how much of a course is finished */
.ring{--p:0;width:34px;height:34px;flex:none;border-radius:50%;display:grid;place-items:center;
  background:conic-gradient(var(--accent) calc(var(--p)*1%),rgba(255,255,255,.1) 0)}
.ring i{width:26px;height:26px;border-radius:50%;background:var(--bg-2);display:grid;place-items:center;
  font:500 9.5px/1 var(--mono);color:var(--muted);font-style:normal}

/* ---------------------------------------------------------------- lesson list */
.lessons{display:grid;gap:0;margin-top:8px}
.lesson-row{display:grid;grid-template-columns:54px minmax(0,1fr) auto 44px;gap:26px;align-items:center;
  padding:26px 16px;margin:0 -16px;border-bottom:1px solid var(--line);
  transition:padding .5s var(--ease),background .4s,border-radius .4s}
.lesson-row:hover{padding-left:28px;background:rgba(255,255,255,.04);border-radius:20px}
.lesson-row .n{font:500 12px/1 var(--mono);letter-spacing:.14em;color:var(--soft)}
.lesson-row h3{font-size:clamp(19px,1.8vw,25px);line-height:1.15;transition:color .3s}
.lesson-row:hover h3{color:var(--hi)}
.lesson-row p{margin-top:6px;font-size:14.5px;max-width:52em}
.lesson-row .tail{display:flex;align-items:center;gap:12px}
.lesson-row .round{transition:all .5s var(--ease)}
.lesson-row:hover .round{background:var(--accent);color:var(--accent-ink);border-color:transparent;transform:rotate(45deg)}
.lesson-row[data-done="1"] .n::after{content:" ✓";color:var(--ok)}

/* ---------------------------------------------------------------- lesson page */
.lesson-wrap{display:grid;grid-template-columns:240px minmax(0,1fr);gap:64px;padding:52px 0 120px;align-items:start}
.lesson-main{min-width:0}
.lesson-main>.prose{max-width:var(--measure)}
/* --measure / --measure-sm are in studio.css, because the reading blocks are not only here.
   The old 74ch put 88 characters on a line, well past where a line stops being comfortable.
   Code, tables and notes keep their full-width boxes; only their text is capped. */
.prose .code,.prose .note,.prose .tablewrap{max-width:none}

.note{margin:0 0 26px;padding:18px 20px;border-radius:16px;border:1px solid var(--line);
  background:rgba(255,255,255,.035);box-shadow:inset 0 1px 0 rgba(255,255,255,.06);display:grid;gap:6px}
.note b{font:500 11px/1.4 var(--mono);letter-spacing:.16em;text-transform:uppercase;color:var(--label)}
.note p{font-size:15px;margin:0;max-width:var(--measure-sm)}  /* the box is full width, the line is not */
.note[data-kind="warn"]{border-color:color-mix(in srgb,var(--no) 40%,transparent)}
.note[data-kind="warn"] b{color:var(--no)}

.tablewrap{overflow-x:auto;margin:0 0 28px;border:1px solid var(--line);border-radius:16px;background:rgba(255,255,255,.025)}
.prose table{border-collapse:collapse;width:100%;font-size:14.5px}
.prose th,.prose td{text-align:left;padding:12px 16px;border-bottom:1px solid var(--line);vertical-align:top}
.prose th{font:500 11px/1.4 var(--mono);letter-spacing:.14em;text-transform:uppercase;color:var(--label);white-space:nowrap}
.prose tr:last-child td{border-bottom:0}
.prose td code{white-space:nowrap}

/* ---------------------------------------------------------------- code blocks */
.code{margin:0 0 28px;border-radius:16px;border:1px solid var(--line);background:var(--code-bg);overflow:hidden}
.code figcaption{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:10px 14px;
  border-bottom:1px solid var(--line);background:rgba(255,255,255,.025)}
.code figcaption .mono{color:var(--dim)}
.code .copy{min-height:26px;padding:5px 10px;border-radius:8px;border:1px solid var(--line);background:rgba(255,255,255,.04);
  color:var(--muted);font:500 10.5px/1 var(--mono);letter-spacing:.14em;text-transform:uppercase;transition:color .3s,background .3s}
.code .copy:hover{color:var(--hi);background:rgba(255,255,255,.09)}
.code pre{margin:0;padding:18px 18px 20px;overflow-x:auto}
.code code,.ed-hl,.ed-ta{font:400 13.5px/1.7 var(--mono);tab-size:2}
.prose p code,.prose li code,.prose td code{font:400 .89em/1.4 var(--mono);padding:2px 6px;border-radius:6px;
  background:rgba(255,255,255,.07);color:var(--ink)}

.t-com{color:var(--t-com);font-style:italic}.t-str{color:var(--t-str)}.t-num{color:var(--t-num)}
.t-key{color:var(--t-key)}.t-tag{color:var(--t-tag)}.t-att{color:var(--t-att)}.t-prop{color:var(--t-prop)}
.t-at{color:var(--t-at)}.t-fn{color:var(--t-fn)}
.code code i,.ed-hl i{font-style:normal}
.t-com{font-style:normal}

/* ---------------------------------------------------------------- the lab */
.lab{margin:34px 0 8px;border-radius:24px;border:1px solid var(--line-2);background:rgba(255,255,255,.03);
  box-shadow:inset 0 1px 0 rgba(255,255,255,.08),0 30px 60px -40px rgba(0,0,0,.9);overflow:hidden}
.lab.solved{border-color:color-mix(in srgb,var(--ok) 50%,transparent)}
.lab-head{display:flex;justify-content:space-between;gap:24px;align-items:flex-start;padding:24px 26px 18px}
.lab-head .mono{display:flex;align-items:center;gap:10px;margin-bottom:10px}
.lab-head .mono i{width:20px;height:1px;background:var(--accent)}
.lab-brief{font-size:16px;color:var(--ink);max-width:64ch;text-wrap:pretty}
.lab-kind{color:var(--soft);text-align:right;white-space:nowrap}
.lab-tasks{margin:0;padding:0 26px 20px 46px;display:grid;gap:7px;font-size:14.5px;color:var(--muted)}
.lab-tasks li{max-width:var(--measure-sm)}
.lab-tasks li::marker{color:var(--soft);font:500 11px var(--mono)}

.lab-body{display:grid;grid-template-columns:1fr 1fr;border-top:1px solid var(--line);min-height:380px}
.lab-edit{display:flex;flex-direction:column;border-right:1px solid var(--line);background:var(--code-bg);min-width:0}
.lab-tabs{display:flex;align-items:center;gap:2px;padding:8px 10px;border-bottom:1px solid var(--line);background:rgba(255,255,255,.02)}
.lab-tabs button{padding:7px 12px;border-radius:9px;font:500 11px/1 var(--mono);letter-spacing:.1em;color:var(--dim);
  border:1px solid transparent;transition:color .3s,background .3s,border-color .3s}
.lab-tabs button:hover{color:var(--muted)}
.lab-tabs button[aria-selected="true"]{color:var(--hi);background:rgba(255,255,255,.07);border-color:var(--line)}
.lab-hint{margin-left:auto;color:var(--soft);opacity:.7}
.ed{position:relative;flex:1;min-height:320px;overflow:hidden}
.ed-hl,.ed-ta{position:absolute;inset:0;margin:0;padding:16px 18px;border:0;white-space:pre;overflow:auto;
  word-break:normal;overflow-wrap:normal}
.ed-hl{color:var(--ink);pointer-events:none;z-index:0}
.ed-ta{z-index:1;resize:none;background:transparent;color:transparent;caret-color:var(--hi);outline:0;display:block}
.ed-ta::selection{background:rgba(255,255,255,.28);color:transparent;-webkit-text-fill-color:transparent}
.ed-ta:focus-visible{outline:0}
.ed:focus-within{box-shadow:inset 0 0 0 1px var(--line-2)}

.lab-view{display:flex;flex-direction:column;min-width:0;background:rgba(0,0,0,.25)}
.lab-bar{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:8px 10px 8px 16px;
  border-bottom:1px solid var(--line);background:rgba(255,255,255,.02)}
.lab-bar .mono{color:var(--soft)}
.lab-frame{flex:1;width:100%;min-height:240px;border:0;background:#fff}
/* A `web` or `page` lab IS a white page — that is what the learner is building. A js, ts,
   node or py lab is a console, so its frame takes the studio surface instead of flashing
   a white sheet into the middle of a dark lesson. */
.lab[data-kind="js"] .lab-frame,.lab[data-kind="ts"] .lab-frame,
.lab[data-kind="node"] .lab-frame,.lab[data-kind="py"] .lab-frame{background:#0f1113}
.lab[data-kind="js"] .lab-frame,.lab[data-kind="node"] .lab-frame{min-height:52px;flex:none;height:52px}
.lab-console{height:150px;overflow:auto;padding:12px 16px;border-top:1px solid var(--line);
  font:400 12.5px/1.65 var(--mono);color:var(--muted);background:rgba(0,0,0,.35)}
.lab[data-kind="js"] .lab-console,.lab[data-kind="node"] .lab-console{height:auto;flex:1;min-height:240px}
.lab-console .ln{margin:0;white-space:pre-wrap;word-break:break-word;color:var(--ink);padding:1px 0}
.lab-console .ln.error{color:var(--no)}
.lab-console .ln.warn{color:var(--t-num)}
.lab-empty{color:var(--soft);margin:0}

.lab-foot{display:flex;justify-content:space-between;gap:28px;align-items:flex-start;padding:18px 26px 22px;
  border-top:1px solid var(--line);flex-wrap:wrap}
.lab-acts{display:flex;gap:8px;flex-wrap:wrap}
.lab-btn{padding:10px 16px;border-radius:11px;border:1px solid var(--line-2);background:rgba(255,255,255,.05);
  color:var(--ink);font:500 12.5px/1 var(--body);letter-spacing:.01em;transition:background .3s,color .3s,border-color .3s}
.lab-btn:hover{background:rgba(255,255,255,.11);color:var(--hi)}
.lab-btn.primary{background:var(--accent);color:var(--accent-ink);border-color:transparent;font-weight:600}
.lab-btn.primary:hover{filter:brightness(1.06);background:var(--accent);color:var(--accent-ink)}
/* min() rather than a flat 260px: the floor keeps the list readable beside the editor on a
   wide screen, and on a 320px phone it stops the list running 25px past the card, where
   the card's own overflow was cutting the end off every check. */
.lab-checks{list-style:none;margin:0;padding:0;display:grid;gap:7px;font-size:14px;color:var(--muted);flex:1;min-width:min(260px,100%)}
.lab-checks li{display:flex;gap:10px;align-items:flex-start}
.lab-checks .mark{width:17px;height:17px;flex:none;margin-top:2px;border-radius:6px;border:1px solid var(--line-2);
  background:rgba(255,255,255,.04);position:relative;transition:background .3s,border-color .3s}
.lab-checks li[data-state="ok"] .mark{background:var(--ok);border-color:transparent}
.lab-checks li[data-state="ok"] .mark::after{content:"✓";position:absolute;inset:0;display:grid;place-items:center;
  font:700 11px/1 var(--body);color:#0a0b0d}
.lab-checks li[data-state="no"] .mark{border-color:var(--no)}
.lab-checks li[data-state="no"] .mark::after{content:"×";position:absolute;inset:0;display:grid;place-items:center;
  font:700 13px/1 var(--body);color:var(--no)}
.lab-checks li[data-state="ok"]{color:var(--ink)}

/* ---------------------------------------------------------------- quiz */
.quiz{margin:44px 0 0;padding:26px;border-radius:22px;border:1px solid var(--line);background:rgba(255,255,255,.03)}
.quiz>.mono{display:flex;align-items:center;gap:10px;margin-bottom:18px}
.quiz>.mono i{width:20px;height:1px;background:var(--accent)}
.q{border:0;margin:0 0 22px;padding:0}
.q legend{font:500 17px/1.4 var(--display);letter-spacing:-.02em;color:var(--hi);margin-bottom:10px;padding:0}
.q label{display:flex;gap:11px;align-items:flex-start;padding:10px 13px;border-radius:12px;border:1px solid var(--line);
  margin-bottom:6px;cursor:pointer;font-size:14.5px;color:var(--muted);transition:background .3s,border-color .3s,color .3s}
.q label:hover{background:rgba(255,255,255,.05);color:var(--ink)}
.q input{margin:3px 0 0;accent-color:var(--accent)}
.q label.right{border-color:color-mix(in srgb,var(--ok) 55%,transparent);color:var(--ink)}
.q .why{margin-top:8px;font-size:14px;padding:11px 14px;border-radius:12px;background:rgba(255,255,255,.04);color:var(--muted)}
.q[data-state="ok"] legend::after{content:" ✓";color:var(--ok)}
.q[data-state="no"] legend::after{content:" ×";color:var(--no)}
.quiz-foot{display:flex;align-items:center;gap:14px}
.quiz-foot .mono{color:var(--muted)}

/* ---------------------------------------------------------------- lesson nav */
.lesson-nav{position:sticky;top:calc(var(--learn-bar-top,88px) + 100px);align-self:start;display:grid;gap:18px}
.lesson-nav .back{font:500 11px/1.4 var(--mono);letter-spacing:.16em;text-transform:uppercase;color:var(--soft);
  display:flex;align-items:center;gap:8px;transition:color .3s}
.lesson-nav .back:hover{color:var(--hi)}
.lesson-steps{display:grid;gap:1px;padding:8px;border-radius:18px;border:1px solid var(--line);background:rgba(255,255,255,.03)}
.lesson-steps a{display:flex;gap:10px;padding:9px 11px;border-radius:11px;font-size:13.5px;color:var(--soft);
  transition:color .3s,background .3s}
.lesson-steps a:hover{color:var(--ink);background:rgba(255,255,255,.05)}
.lesson-steps a[aria-current="true"]{color:var(--hi);background:rgba(255,255,255,.08)}
.lesson-steps a .mono{color:inherit;opacity:.65;flex:none}
.lesson-steps a[data-done="1"] .mono::after{content:"✓";margin-left:4px;color:var(--ok);opacity:1}

.pager{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-top:64px}
.pager a{padding:24px 26px;border-radius:20px;border:1px solid var(--line);background:rgba(255,255,255,.03);
  transition:background .4s,border-color .4s,transform .5s var(--ease)}
.pager a:hover{background:rgba(255,255,255,.06);border-color:var(--line-2);transform:translateY(-3px)}
.pager .mono{color:var(--soft);margin-bottom:8px;display:block}
.pager b{font:500 19px/1.25 var(--display);letter-spacing:-.03em;color:var(--hi);display:block}
.pager .prev{text-align:left}.pager .next-l{text-align:right}
.pager a.ghost{opacity:.4;pointer-events:none}

/* ---------------------------------------------------------------- playground */
.pg{margin:0 0 90px}
.pg .lab{margin-top:0}
.pg .lab-body{min-height:620px}
.pg .ed{min-height:560px}
.pg .lab-frame{min-height:420px}

@media (max-width:1100px){
  .courses{grid-template-columns:repeat(2,1fr)}
  .lesson-wrap{grid-template-columns:1fr;gap:34px}
  .lesson-nav{position:static}
  .lesson-steps{grid-template-columns:repeat(2,1fr);display:grid}
}
@media (max-width:820px){
  .courses{grid-template-columns:1fr}
  .lab-body{grid-template-columns:1fr}
  .lab-edit{border-right:0;border-bottom:1px solid var(--line)}
  .ed{min-height:260px}
  .lesson-row{grid-template-columns:44px minmax(0,1fr) 40px;gap:14px}
  .lesson-row .tail{display:none}
  .lesson-steps{grid-template-columns:1fr}
  .pager{grid-template-columns:1fr}
  .lab-head{flex-direction:column;gap:10px}
  /* `nowrap` was right beside a right-aligned column and wrong once it stacked: on a phone
     "CPython 3.14, compiled to WebAssembly" ran 182px past the card and was cut off. */
  .lab-kind{text-align:left;white-space:normal}
  .lab-tabs{flex-wrap:wrap;row-gap:6px}
  .lab-hint{margin-left:0}
}

/* the shortcut names two keys the device does not have */
@media (pointer:coarse){
  .lab-hint{display:none}
}

/* ---------------------------------------------------------------- reference */
.ref-bar{position:sticky;top:calc(var(--learn-bar-top,88px) + 84px);z-index:6;padding:14px 0 12px;
  background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(18px);
  border-bottom:1px solid var(--line)}
.ref-bar-in{display:flex;align-items:center;gap:18px;flex-wrap:wrap}
.ref-sets{display:flex;gap:2px;max-width:100%;padding:4px;border-radius:14px;border:1px solid var(--line);
  background:rgba(255,255,255,.035);overflow-x:auto;scrollbar-width:none}
.ref-sets::-webkit-scrollbar{display:none}
.ref-sets button{flex:none}
.ref-sets button{display:flex;align-items:center;gap:8px;padding:8px 14px;border-radius:10px;
  font:500 13px/1 var(--body);color:var(--soft);transition:color .3s,background .3s}
.ref-sets button .mono{font-size:10px;color:inherit;opacity:.6}
.ref-sets button:hover{color:var(--ink)}
.ref-sets button[aria-selected="true"]{color:var(--accent-ink);background:var(--accent)}
.ref-sets button[aria-selected="true"] .mono{opacity:.7}
.ref-search{display:flex;align-items:center;gap:9px;flex:1;min-width:200px;padding:9px 14px;border-radius:12px;
  border:1px solid var(--line);background:rgba(255,255,255,.035);color:var(--soft)}
.ref-search:focus-within{border-color:var(--line-2);color:var(--ink)}
.ref-search input{flex:1;min-width:0;background:none;border:0;outline:0;color:var(--ink);font:400 14px var(--body)}
.ref-search input::placeholder{color:var(--soft)}
.ref-cats{display:flex;gap:6px;flex-wrap:wrap;margin-top:12px}
.ref-cats .tagx{cursor:pointer;transition:color .3s,background .3s,border-color .3s}
.ref-cats .tagx:hover{color:var(--hi);border-color:var(--line-2)}
.ref-cats .tagx.on{color:var(--accent-ink);background:var(--accent);border-color:transparent}

/* minmax(0,1fr): a grid item defaults to min-width:auto, so one long unwrapped line
   inside a <pre> used to stretch the whole track and scroll the page sideways. */
.ref-list{display:grid;grid-template-columns:minmax(0,1fr);gap:14px;padding:32px 0 20px}
/* 415 entries in one column is a 39,000px page and half a desktop screen of nothing. Two
   columns from 1180px; `minmax(0,1fr)` is what stops a long line inside a <pre> from
   stretching a track, not the single column, so the phone fix holds. */
@media (min-width:1180px){.ref-list{grid-template-columns:repeat(2,minmax(0,1fr));align-items:start}}
.ref-item>p{max-width:var(--measure-sm)}
.ref-item{min-width:0;padding:22px 24px 18px;border-radius:18px;border:1px solid var(--line);background:rgba(255,255,255,.028);
  scroll-margin-top:264px}
.ref-item:target{border-color:var(--line-2);background:rgba(255,255,255,.06)}
.ref-head{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-bottom:10px;flex-wrap:wrap}
.ref-head h2{margin:0;font-size:17px}
.ref-head h2 code{font:500 16px/1.4 var(--mono);color:var(--hi);background:rgba(255,255,255,.07);padding:4px 9px;border-radius:7px}
.ref-desc{margin:0 0 14px;font-size:15px;color:var(--muted);max-width:76ch;text-wrap:pretty}
.ref-item .code{margin-bottom:14px}
.ref-item .note{margin-bottom:0}
.ref-foot{display:flex;gap:16px;flex-wrap:wrap;margin-top:12px}
.ref-foot a{font:500 10.5px/1 var(--mono);letter-spacing:.14em;text-transform:uppercase;color:var(--soft);transition:color .3s}
.ref-foot a:hover{color:var(--hi)}
.ref-empty{padding:40px 0 80px;color:var(--soft)}

/* ---------------------------------------------------------------- continue panel */
.continue{display:grid;grid-template-columns:1fr auto;gap:24px;align-items:center;
  padding:24px 26px;border-radius:22px;border:1px solid var(--line-2);background:rgba(255,255,255,.05);
  box-shadow:inset 0 1px 0 rgba(255,255,255,.08);margin-bottom:28px}
.continue .mono{color:var(--label);margin-bottom:8px;display:flex;align-items:center;gap:10px}
.continue .mono i{width:20px;height:1px;background:var(--accent)}
.continue b{display:block;font:500 clamp(20px,2.2vw,28px)/1.1 var(--display);letter-spacing:-.03em;color:var(--hi)}
.continue p{margin:6px 0 0;font-size:14px}
@media (max-width:700px){.continue{grid-template-columns:1fr}}

/* ------------------------------------------------------------------ builds
   A build is a lesson's opposite number: one project, several steps, each an ordinary lab.
   Only the open step mounts its editor, so five iframes never exist at once. */
.build-course{margin-top:18px;font-size:12px;color:var(--muted)}
.build-course a{color:var(--cyan)}
.build-outcome{padding:56px 0 8px}
.build-outcome>.mono{font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);margin:0 0 14px}
.build-outcome ul{list-style:none;margin:0;padding:0;display:grid;gap:10px;max-width:56rem}
.build-outcome li{position:relative;padding-left:26px;color:var(--fg-2)}
.build-outcome li::before{content:"";position:absolute;left:4px;top:.62em;width:8px;height:8px;border-radius:50%;background:var(--cyan);opacity:.55}

.build-steps{list-style:none;margin:40px 0 0;padding:0;display:grid;gap:12px;counter-reset:step}
.build-step{border:1px solid var(--line);border-radius:18px;background:rgba(255,255,255,.015);overflow:hidden;transition:border-color .25s ease,background .25s ease}
.build-step.open{border-color:var(--line-2);background:rgba(255,255,255,.03)}
.build-step[data-state=done]{border-color:rgba(0,234,220,.28)}
.step-head{display:flex;align-items:center;gap:18px;width:100%;padding:18px 20px;background:none;border:0;text-align:left;color:inherit;cursor:pointer}
.step-head:hover{background:rgba(255,255,255,.03)}
.step-no{font-size:12px;color:var(--muted);min-width:2ch}
.build-step[data-state=done] .step-no{color:var(--cyan)}
.step-title{display:grid;gap:3px;flex:1}
.step-title b{font-weight:500;font-size:17px}
.step-sum{font-size:13px;color:var(--muted)}
.step-mark{width:22px;height:22px;border-radius:50%;border:1px solid var(--line-2);position:relative;flex:none}
.step-mark::after{content:"";position:absolute;inset:5px;border-radius:50%;background:var(--cyan);opacity:0;transition:opacity .25s ease}
.build-step[data-state=done] .step-mark{border-color:rgba(0,234,220,.5)}
.build-step[data-state=done] .step-mark::after{opacity:1}
.step-panel{padding:0 20px 20px;border-top:1px solid var(--line)}
.step-brief{max-width:var(--measure);margin:18px 0 20px;color:var(--fg-2)}  /* 52rem was 104 characters a line */
.step-foot{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-top:16px;flex-wrap:wrap}
.step-state{font-size:12px;color:var(--muted)}
.build-step[data-state=done] .step-state{color:var(--cyan)}
.build-after{padding:64px 0 24px}
.build-after>.mono{font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);margin:0 0 14px}
.course.is-soon{opacity:.45;cursor:default}
/* At 320px the three set buttons were 10px wider than the screen and scrolled the page
   sideways. Tighter padding fits them; the group also scrolls, so nothing is ever cut off. */
@media (max-width:420px){
  .ref-sets button{padding:8px 9px;gap:5px}
  .ref-bar-in{gap:12px}
}

@media (max-width:640px){
  .step-head{padding:15px 14px;gap:12px}
  .step-panel{padding:0 12px 16px}
}

/* ------------------------------------------------------------------ Night shift
   The game: twenty levels in five worlds. The map screen lists them; the play screen is a
   canvas the replay is drawn on, an editor, and the level list beside it. The player's code
   runs in a sandboxed frame — nothing here is trusted with the page. */
.game{display:grid;grid-template-columns:270px 1fr;gap:24px;align-items:start;padding:24px 0 80px}
.game-list{display:grid;gap:6px;position:sticky;top:96px;max-height:calc(100vh - 130px);overflow:auto;padding-right:6px;align-content:start}
.game-back{display:flex;align-items:center;gap:8px;padding:8px 2px;font-size:12px;color:var(--muted);text-decoration:none}
.game-back:hover{color:var(--fg)}
.game-back i{width:14px;height:1px;background:currentColor;position:relative}
.game-back i::before{content:"";position:absolute;left:0;top:-3px;width:7px;height:7px;border-left:1px solid currentColor;border-bottom:1px solid currentColor;transform:rotate(45deg)}
.game-world{margin:14px 0 2px;font-size:10px;letter-spacing:.16em;text-transform:uppercase;color:var(--muted);opacity:.7}
.game-world:first-of-type{margin-top:4px}
.game-item{display:flex;align-items:center;gap:12px;width:100%;padding:11px 13px;border:1px solid var(--line);border-radius:12px;background:none;color:inherit;text-align:left;cursor:pointer;transition:border-color .2s ease,background .2s ease}
.game-item:hover{background:rgba(255,255,255,.03)}
.game-item[aria-current=true]{border-color:var(--line-2);background:rgba(255,255,255,.05)}
.game-item .mono{font-size:11px;color:var(--muted)}
.game-item b{display:block;font-weight:500;font-size:14px}
.game-item small{display:block;font-size:11px;color:var(--muted);margin-top:2px}
.game-item i{flex:none;font-style:normal}
.game-item[data-state=done] .mono{color:var(--cyan)}
.game-item[data-state=shut]{opacity:.4;cursor:default}
.game-item[data-state=shut]:hover{background:none}
.stars{font-size:11px;letter-spacing:1px;color:var(--cyan);white-space:nowrap}

.game-main{display:grid;gap:18px;min-width:0}
.game-head .mono{font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted);margin:0 0 6px}
.game-head h2{font-size:clamp(24px,3vw,34px);margin:0 0 10px;letter-spacing:-.02em}
.game-brief{max-width:60ch;color:var(--fg-2);margin:0 0 14px}
.game-goals{list-style:none;margin:0;padding:0;display:grid;gap:6px}
.game-goals li{display:flex;align-items:flex-start;gap:10px;font-size:14px;color:var(--muted)}
.game-goals .mark{width:14px;height:14px;border-radius:50%;border:1px solid var(--line-2);flex:none;margin-top:4px;position:relative}
.game-goals li[data-state=ok]{color:var(--fg-2)}
.game-goals li[data-state=ok] .mark{border-color:var(--cyan);background:var(--cyan)}
.game-goals li[data-state=no] .mark{border-color:#c2452d}

.game-stage{display:grid;grid-template-columns:auto 1fr;gap:18px;align-items:start;padding:18px;border:1px solid var(--line);border-radius:18px;background:rgba(255,255,255,.015);overflow:auto}
.game-stage canvas{display:block;border-radius:10px;background:rgba(0,0,0,.25)}
.game-stage-side{display:grid;gap:10px;min-width:0}
.game-stage-side .mono{font-size:12px;color:var(--muted);margin:0}
.game-stage-side .mono[data-kind=ok]{color:var(--cyan)}
.game-stage-side .mono[data-kind=error],.game-stage-side .mono[data-kind=no]{color:#c2452d}
.game-key{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:7px 14px;font-size:11px;color:var(--muted)}
.game-key li{display:flex;align-items:center;gap:6px}
.game-key i{width:12px;height:12px;border-radius:3px;flex:none;font-style:normal;font-size:11px;line-height:12px;text-align:center}
.game-key i[data-k=door]{background:rgba(233,196,106,.85)}
.game-key i[data-k=red]{background:#ff7a7a}
.game-key i[data-k=blue]{background:#79aaff}
.game-key i[data-k=green]{background:#5fd18c}
.game-key i[data-k^=bin]{border:1px dashed var(--cyan);border-radius:2px}
.game-key i[data-k=bin-red]{border-color:#ff7a7a}
.game-key i[data-k=bin-blue]{border-color:#79aaff}
.game-key i[data-k=bin-green]{border-color:#5fd18c}
.game-key i[data-k=crate]{background:rgba(255,255,255,.18);border:1px solid rgba(255,255,255,.4)}
.game-key i[data-k=plate]{background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.35);border-radius:50%}
.game-key i[data-k=gate]{height:5px;background:rgba(233,196,106,.75)}
.game-key i[data-k=charge]{color:var(--cyan)}
.game-log{font:12px/1.6 var(--mono,ui-monospace,monospace);color:var(--muted);max-height:220px;overflow:auto;display:grid;gap:2px;align-content:start}
.game-log p{margin:0}

.game-code{border:1px solid var(--line);border-radius:18px;overflow:hidden}
.game-code .ed{min-height:320px}
.game-acts{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.game-par{margin-left:auto;font-size:12px;color:var(--muted)}
.game-head .game-teach{font-size:11px;color:var(--muted);margin:0 0 14px}
.game-api{border:1px solid var(--line);border-radius:14px;padding:0 16px}
.game-api summary{padding:12px 0;font-size:13px;color:var(--fg-2);cursor:pointer;list-style:none}
.game-api summary::-webkit-details-marker{display:none}
.game-api summary::before{content:"+";display:inline-block;width:16px;color:var(--muted)}
.game-api[open] summary::before{content:"–"}
.game-api dl{margin:0 0 14px;display:grid;gap:6px}
.game-api dl div{display:grid;grid-template-columns:230px minmax(0,1fr);gap:14px;align-items:baseline}
.game-api dt{margin:0}
.game-api dt code{font-size:12px;color:var(--cyan);background:none;padding:0}
.game-api dd{margin:0;font-size:12px;color:var(--muted)}
@media (max-width:700px){ .game-api dl div{grid-template-columns:1fr;gap:2px} }

.game-score{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;
  border-top:1px solid var(--line);padding-top:14px}
.game-score p{display:flex;align-items:center;gap:10px;margin:0;font-size:12px;color:var(--muted)}
.game-score .stars{font-size:14px}
.game-move{display:flex;gap:8px}
.game-move [data-state=shut]{opacity:.35;pointer-events:none}

/* the map: five worlds, four levels each, and what you have taken out of them */
.game-map{display:grid;gap:8px;padding:8px 0 90px}
.world{display:grid;grid-template-columns:250px minmax(0,1fr);gap:28px;padding:30px 0;border-top:1px solid var(--line)}
.world header{position:sticky;top:150px;align-self:start}
.world header .mono{font-size:11px;letter-spacing:.16em;text-transform:uppercase;color:var(--muted);margin:0 0 8px}
.world header h2{font-size:clamp(22px,2.4vw,30px);margin:0 0 8px;letter-spacing:-.02em}
.world header p{font-size:14px;color:var(--muted);margin:0;max-width:34ch}
.world-stars{margin-top:12px!important;color:var(--cyan)!important;letter-spacing:.08em!important;text-transform:none!important}
.world[data-state=shut]{opacity:.55}
/* Four levels to a world. `auto-fill` puts three on a line between 640px and 1024px and leaves
   the fourth alone underneath, so below the width where four fit they go two by two instead. */
.world-levels{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px}
@media (max-width:1100px){.world-levels{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:460px){.world-levels{grid-template-columns:minmax(0,1fr)}}
.lvl{display:grid;gap:3px;align-content:start;padding:16px;border:1px solid var(--line);border-radius:16px;
  color:inherit;text-decoration:none;background:rgba(255,255,255,.012);
  transition:border-color .2s ease,background .2s ease,transform .2s ease}
.lvl:hover{border-color:var(--line-2);background:rgba(255,255,255,.04);transform:translateY(-2px)}
.lvl .mono{font-size:11px;color:var(--muted)}
.lvl b{font-weight:500;font-size:15px;letter-spacing:-.01em}
.lvl small{font-size:11px;color:var(--muted)}
.lvl .stars{margin-top:8px}
.lvl[data-state=done]{border-color:color-mix(in srgb,var(--cyan) 35%,var(--line))}
.lvl[data-state=done] .mono{color:var(--cyan)}
.lvl[data-state=shut]{opacity:.4;background:none}
.lvl[data-state=shut]:hover{transform:none;border-color:var(--line);background:none}

@media (max-width:900px){
  .game{grid-template-columns:1fr}
  .game-list{position:static;max-height:none;overflow:visible}
  .game-stage{grid-template-columns:1fr}
  .world{grid-template-columns:1fr;gap:16px}
  .world header{position:static}
}

/* ------------------------------------------------------------------ the learn bar
   One row, on every page under /learn: where you are, and the other four places you
   can go. It sticks under the floating header so it is reachable from anywhere. */
/* it rests just under the floating header and sticks there, so it is never hidden by it */
/* The same floating glass panel the filters bar on /templates/ and /work/ is — a rail under the
   header rather than a band across the page. The panel itself is drawn by the shared recipe in
   pages.css; what is here is its geometry. */
.learn-bar{position:sticky;top:var(--learn-bar-top,88px);z-index:7;
  margin-top:calc(var(--learn-bar-top,88px) + 8px);padding:12px 0;pointer-events:none}
.learn-bar + .intro{padding-top:36px}
.learn-bar-in{pointer-events:auto;display:flex;align-items:center;gap:20px;height:60px;padding:0 10px;
  border-radius:20px;border:1px solid var(--line-2);overflow-x:auto;scrollbar-width:none}
.learn-bar-in::-webkit-scrollbar{display:none}
.learn-home{display:inline-flex;align-items:center;gap:8px;font:500 12px/1 var(--mono);letter-spacing:.16em;text-transform:uppercase;color:var(--hi);white-space:nowrap}
.learn-home i{width:7px;height:7px;border-radius:50%;background:var(--accent)}
/* No box inside the box: the panel is the container, so the places sit straight on it the way
   the filter buttons do on /templates/. Only the current one is drawn. */
.learn-places{display:flex;gap:2px;flex:none}
.learn-places a{padding:6px 12px;border-radius:9px;font-size:13px;color:var(--soft);white-space:nowrap;transition:color .25s ease,background .25s ease}
.learn-places a:hover{color:var(--ink)}
.learn-places a[aria-current=page]{color:var(--accent-ink);background:var(--accent)}
.learn-trail{display:flex;align-items:center;gap:8px;font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--soft);white-space:nowrap}
.learn-trail a{color:var(--soft)}
.learn-trail a:hover{color:var(--hi)}
.learn-trail i{opacity:.4;font-style:normal}
.learn-bar-end{margin-left:auto;display:flex;align-items:center;gap:10px;flex:none}
.learn-next{display:inline-flex;align-items:center;gap:8px;padding:7px 14px;border-radius:999px;border:1px solid var(--line-2);
  font-size:13px;color:var(--ink);white-space:nowrap;transition:background .25s ease,border-color .25s ease}
.learn-next:hover{background:rgba(255,255,255,.06)}
.learn-next kbd{font:500 10px/1 var(--mono);padding:3px 5px;border-radius:5px;border:1px solid var(--line-2);color:var(--soft)}

/* ------------------------------------------------------------------ the page map */
.lesson-main{display:grid;grid-template-columns:minmax(0,74ch) 1fr;gap:56px;align-items:start}
.lesson-main>.prose{grid-column:1}
.lesson-main>[data-lab],.lesson-main>#practice,.lesson-main>[data-quiz],.lesson-main>.pager{grid-column:1/-1}
.lesson-map{grid-column:2;position:sticky;top:76px;align-self:start;display:grid;gap:10px;padding-top:6px;max-height:calc(100vh - 120px);overflow:auto;scrollbar-width:none}
.lesson-map::-webkit-scrollbar{display:none}
.map-head{font-size:10px;letter-spacing:.16em;text-transform:uppercase;color:var(--soft);margin:0}
.map-list{list-style:none;margin:0;padding:0;display:grid;gap:1px;border-left:1px solid var(--line)}
.map-list a{display:flex;gap:9px;padding:6px 12px;font-size:13px;line-height:1.35;color:var(--soft);border-left:2px solid transparent;margin-left:-1px;transition:color .25s ease,border-color .25s ease}
.map-list a .mono{font-size:10px;opacity:.55;padding-top:2px}
.map-list a:hover{color:var(--ink)}
.map-list a[aria-current=true]{color:var(--hi);border-left-color:var(--accent)}
.map-jump{display:inline-block;margin-top:6px;font-size:12px;color:var(--accent)}
.map-jump:hover{text-decoration:underline}

/* ------------------------------------------------------------------ course rail */
.lesson-progress{display:grid;gap:6px}
.lesson-progress .bar{height:3px;border-radius:2px;background:rgba(255,255,255,.08);overflow:hidden}
.lesson-progress .bar i{display:block;height:100%;background:var(--accent);transition:width .4s var(--ease)}
.lesson-progress .mono{font-size:10.5px;letter-spacing:.1em;text-transform:uppercase;color:var(--soft);margin:0}
.lesson-steps-wrap summary{font-size:10.5px;letter-spacing:.14em;text-transform:uppercase;color:var(--soft);cursor:pointer;padding:2px 0 8px;list-style:none}
.lesson-steps-wrap summary::-webkit-details-marker{display:none}
.lesson-steps-wrap summary::before{content:"▾ ";opacity:.5}
.lesson-steps-wrap:not([open]) summary::before{content:"▸ "}

@media (max-width:1560px){
  .lesson-main{grid-template-columns:minmax(0,1fr)}
  .lesson-map{display:none}
}
@media (max-width:860px){
  .learn-bar{padding:8px 0}
  .learn-bar-in{height:54px;border-radius:17px;padding:0 6px;gap:14px}
  .learn-trail{display:none}
  .learn-next{padding:6px 11px;font-size:12px}
  .learn-next kbd{display:none}
}

/* The bar scrolls sideways when the places do not fit, which used to carry the one thing on
   the page you actually want — "Start at the beginning" — off the right edge: at 375px it sat
   270px past it, reachable only by discovering a sideways scroll. Sticky keeps it against the
   edge of the scrollport while the chips pass underneath, and the fade stops them colliding. */
@media (max-width: 860px) {
  /* The fade is the PANEL's colour, not the page's: the bar is a translucent glass rail now, and
     a fade to `--bg` painted a dark block across the middle of it. */
  .learn-bar-end{position:sticky;right:0;padding-left:30px;
    background:linear-gradient(90deg,transparent,#0f1115 58%)}
  .learn-next{background:rgba(255,255,255,.08);border-color:rgba(255,255,255,.2)}
}
.learn-next .short{display:none}
@media (max-width: 560px) {
  .learn-next .long{display:none}
  .learn-next .short{display:inline}
}

/* The standalone links — a breadcrumb, a footer action, the back link — are set in small
   mono and were 11–15px tall. Padding the hit area to 44px leaves the type where it is;
   only the region that answers a finger changes. Links inside prose are left alone,
   because a 44px line box would break the paragraph they sit in. */
@media (pointer:coarse),(max-width:860px){
  .crumbs a,.ref-foot a,.lesson-nav .back,.map-jump,.build-course a{
    display:inline-flex;align-items:center;min-height:44px}
  .ref-foot{gap:16px 20px;margin-top:4px}
}

/* On a finger, a 12px-tall link is a miss. The bar is 48px high, so its items take the
   whole height: the hit area becomes 48px and nothing about the design changes. */
@media (pointer:coarse),(max-width:860px){
  .learn-bar-in > *{align-self:stretch}
  .learn-home,.learn-bar-end,.learn-bar-end > a,.learn-places a,.learn-trail a{
    display:inline-flex;align-items:center;min-height:44px}
  .learn-places{align-items:stretch}
  .learn-places a{padding-top:0;padding-bottom:0}
}

/* how many entries the filter is showing, so the page says what it is doing */
.ref-count{margin-left:auto;font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--soft);white-space:nowrap}
.ref-top{position:fixed;right:24px;bottom:24px;z-index:8;display:none;align-items:center;gap:8px;padding:10px 16px;border-radius:999px;
  border:1px solid var(--line-2);background:color-mix(in srgb,var(--bg) 82%,transparent);backdrop-filter:blur(14px);
  font-size:12px;color:var(--ink);cursor:pointer}
.ref-top[data-on="1"]{display:inline-flex}

/* a course page says how far in you are, in one line */
.course-progress{display:grid;gap:7px;margin-top:20px;max-width:26rem}
.course-progress .bar{height:4px;border-radius:2px;background:rgba(255,255,255,.08);overflow:hidden}
.course-progress .bar i{display:block;height:100%;background:var(--accent);transition:width .5s var(--ease)}
.course-progress .mono{font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--soft);margin:0}

/* ------------------------------------------------------------------ continuity
   The bar and the title carry across a navigation, so moving between lessons reads as
   one place changing rather than two pages swapping. */
.learn-bar{view-transition-name:learn-bar}
body[data-lesson] .intro h1{view-transition-name:page-title}
@media (prefers-reduced-motion:reduce){
  .learn-bar,body[data-lesson] .intro h1{view-transition-name:none}
}

/* the map and the rail on a phone: the rail collapses, the map is not shown at all */

@media (max-width:860px){
  .lesson-nav{top:auto}
  .lesson-steps{max-height:52vh;overflow:auto}
}

/* once the practice is passed, the next lesson is the thing to notice */
.learn-next.is-ready{border-color:var(--accent);color:var(--accent);background:color-mix(in srgb,var(--accent) 12%,transparent)}

/* On a large screen the learn pages take the room: the prose stays at a readable measure,
   and the extra width goes to the editor, the preview and the page map. */
@media (min-width:1700px){
  body[data-page=learn]{--wrap:min(1680px,calc(100% - 120px))}
  .lesson-main{grid-template-columns:minmax(0,74ch) 1fr;gap:72px}
  .lesson-wrap{grid-template-columns:260px minmax(0,1fr);gap:72px}
}

/* ---------- teardowns (/library/<id>/) ---------- */
/* A teardown is one reading column plus one live toy. The column is centred because a teardown has
   no page-map rail beside it, and it sits directly in .wrap: inside .lesson-main (a grid) a
   max-width-capped item takes a max-content track and came out 680px wide on a 343px phone.
   Each page adds only its own scene (.toy-sky, .toy-wall …); the frame, the control and the
   readouts are this one component. */
.teardown{max-width:var(--measure);margin-inline:auto;min-width:0}
.toy{margin:0 0 30px;border-radius:18px;border:1px solid var(--line);background:var(--code-bg);overflow:hidden}
.toy-head{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:10px 14px;
  border-bottom:1px solid var(--line);font:500 11px/1.4 var(--mono);letter-spacing:.14em;
  text-transform:uppercase;color:var(--label)}
.toy-ctrl{display:flex;align-items:center;gap:14px;padding:14px 16px;border-top:1px solid var(--line)}
.toy-ctrl label{font:500 11px/1 var(--mono);letter-spacing:.14em;text-transform:uppercase;color:var(--label)}
.toy-ctrl input[type=range]{flex:1;min-width:0;min-height:44px;accent-color:var(--hi);background:transparent}
/* min-width:0 — a range input keeps an intrinsic ~130px floor, so at 320px the row ran 14px past
   the frame and the readout was clipped. The slider is the part that can afford to shrink. */
.toy-clock{flex:none;font:500 22px/1 var(--display);color:var(--hi);font-variant-numeric:tabular-nums;min-width:74px;text-align:right}
/* flex:none — the readout keeps its width; the slider gives way instead (below) */
.toy-read{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1px;background:var(--line);border-top:1px solid var(--line)}
.toy-read div{padding:12px 14px;background:var(--code-bg)}
.toy-read b{display:block;font:500 19px/1.2 var(--display);color:var(--hi);font-variant-numeric:tabular-nums}
.toy-read span{font:500 10px/1.4 var(--mono);letter-spacing:.13em;text-transform:uppercase;color:var(--label)}
@media (max-width:560px){ .toy-read{grid-template-columns:repeat(2,minmax(0,1fr))} }
/* A choice of a few named states (a workload, an algorithm) sits in the same control row as a
   slider: a segmented group of radio buttons. 44px tall so a thumb can hit it. */
.toy-seg{display:flex;gap:4px;padding:3px;border-radius:14px;border:1px solid var(--line);background:rgba(255,255,255,.03)}
.toy-seg button{flex:1;min-height:44px;padding:0 12px;border-radius:11px;border:1px solid transparent;background:transparent;
  font:500 13px/1 var(--body);color:var(--muted);cursor:pointer;white-space:nowrap}
.toy-seg button:hover{color:var(--hi);background:rgba(255,255,255,.05)}
.toy-seg button[aria-checked="true"]{color:var(--hi);background:rgba(255,255,255,.12);border-color:rgba(255,255,255,.16);box-shadow:inset 0 1px 0 rgba(255,255,255,.12)}
.toy-seg button:focus-visible{outline:2px solid var(--hi);outline-offset:1px}
.toy-ctrl.is-seg{padding:10px 12px}
.toy-ctrl.is-seg .toy-seg{flex:1;min-width:0}
.toy-seg button{min-width:0}
/* four choices do not fit one row at 320px ("Counting" was cut off): they go two by two */
@media (max-width:420px){ .toy-seg:has(>:nth-child(4):last-child){display:grid;grid-template-columns:1fr 1fr} }