/* Pixel School — a pixel artist's sketchbook.
   Theme = CSS variables. Light is the default; dark applies when the OS asks
   for it OR when the user picks it (data-theme="dark" on <html>). */

:root {
  --paper: #f4edde;
  --paper-2: #ebe1cb;
  --card: #fbf6ea;
  --ink: #2b2118;
  --ink-soft: #5b4d3e;
  --rule: #cdbf9f;
  --grid: rgba(43, 33, 24, .06);
  --accent: #c4572e;
  --accent-ink: #fff8ee;
  --good: #3f7a4a;
  --warn: #b8700f;
  --fix: #b3261e;
  --shadow: rgba(43, 33, 24, .22);
  /* The drawing canvas is "paper" in BOTH themes so dark ink stays readable. */
  --canvas: #e8dfc9;
  --font-head: "Silkscreen", "Courier New", monospace;
  --font-body: "Atkinson Hyperlegible", system-ui, -apple-system, "Segoe UI", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) { --paper:#1d1814; --paper-2:#26201a; --card:#272019; --ink:#f0e6d2; --ink-soft:#bcae95; --rule:#4a3f33; --grid:rgba(240,230,210,.05); --accent:#e8884f; --accent-ink:#1d1814; --good:#7fc08a; --warn:#e3a54a; --fix:#ff8a80; --shadow:rgba(0,0,0,.5); }
}
:root[data-theme="dark"] { --paper:#1d1814; --paper-2:#26201a; --card:#272019; --ink:#f0e6d2; --ink-soft:#bcae95; --rule:#4a3f33; --grid:rgba(240,230,210,.05); --accent:#e8884f; --accent-ink:#1d1814; --good:#7fc08a; --warn:#e3a54a; --fix:#ff8a80; --shadow:rgba(0,0,0,.5); }

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; color: var(--ink); background-color: var(--paper);
  /* graph-paper grid */
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
  font: 18px/1.55 var(--font-body);
}
h1, h2, h3 { font-family: var(--font-head); font-weight: 700; line-height: 1.2; letter-spacing: .02em; margin: 0 0 .5em; }
h1 { font-size: clamp(1.6rem, 5vw, 2.4rem); }
h2 { font-size: 1.25rem; }
h3 { font-size: 1rem; }
a { color: var(--accent); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.wrap { max-width: 980px; margin: 0 auto; padding: 16px; }

/* ---------- header ---------- */
.top { border-bottom: 2px solid var(--ink); background: var(--paper-2); }
.top .wrap { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; padding-block: 10px; }
.brand { font-family: var(--font-head); font-weight: 700; font-size: 1.2rem; color: var(--ink); text-decoration: none; margin-right: auto; display: flex; align-items: center; gap: 8px; }
.brand i { width: 14px; height: 14px; background: var(--accent); box-shadow: 14px 0 0 var(--ink), 0 14px 0 var(--ink); display: inline-block; margin-right: 14px; }
.top a.nav { color: var(--ink); text-decoration: none; padding: 4px 8px; }
.top a.nav:hover { text-decoration: underline; }

/* ---------- buttons ---------- */
.btn {
  font: 600 .9rem/1 var(--font-body); color: var(--ink); background: var(--card);
  border: 2px solid var(--ink); border-radius: 4px; padding: 9px 12px; min-height: 40px;
  cursor: pointer; box-shadow: 2px 2px 0 var(--shadow);
}
.btn:hover { background: var(--paper-2); }
.btn:active { transform: translate(1px, 1px); box-shadow: 1px 1px 0 var(--shadow); }
.btn[aria-pressed="true"], .btn.on { background: var(--ink); color: var(--paper); }
.btn.primary { background: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { filter: brightness(1.08); }
.btn:disabled { opacity: .4; cursor: not-allowed; box-shadow: none; }
.btn kbd { font: inherit; font-size: .7rem; opacity: .65; margin-left: 4px; }

/* ---------- cards / sections ---------- */
.card { background: var(--card); border: 2px solid var(--ink); border-radius: 4px; padding: 18px; box-shadow: 4px 4px 0 var(--shadow); margin-block: 20px; }
.lead { font-size: 1.15rem; color: var(--ink-soft); max-width: 60ch; }
.crumbs { font-size: .9rem; margin-top: 8px; }

/* ---------- lesson path / checklist ---------- */
.path { list-style: none; margin: 0; padding: 0; position: relative; }
.path li { position: relative; padding: 0 0 18px 52px; }
.path li::before { content: ""; position: absolute; left: 17px; top: 36px; bottom: 0; border-left: 3px dotted var(--rule); }
.path li:last-child::before { display: none; }
.path .mk { position: absolute; left: 0; top: 0; width: 36px; height: 36px; display: grid; place-items: center; font: 700 .9rem var(--font-head); background: var(--card); border: 2px solid var(--ink); }
.path li.done .mk { background: var(--good); color: #fff; border-color: var(--good); }
.path li.soon { opacity: .6; }
.path a { font-weight: 700; color: var(--ink); }
.path p { margin: 2px 0 0; color: var(--ink-soft); font-size: .95rem; }
.tag { font: .7rem var(--font-head); border: 1px solid var(--rule); padding: 1px 5px; margin-left: 6px; color: var(--ink-soft); vertical-align: middle; }

/* compact trail at the top of a lesson */
.trail { display: flex; flex-wrap: wrap; gap: 6px; list-style: none; padding: 0; margin: 12px 0 0; }
.trail a, .trail span { display: grid; place-items: center; width: 34px; height: 34px; font: 700 .8rem var(--font-head); border: 2px solid var(--ink); background: var(--card); color: var(--ink); text-decoration: none; }
.trail .done a { background: var(--good); border-color: var(--good); color: #fff; }
.trail .here a { background: var(--accent); color: var(--accent-ink); }
.trail .soon span { opacity: .45; border-style: dashed; }

/* ---------- lesson layout ---------- */
.explain { display: grid; gap: 20px; grid-template-columns: 1fr; }
@media (min-width: 800px) { .explain { grid-template-columns: 1.1fr 1fr; align-items: start; } }
.explain p { margin: 0 0 .8em; }
.demo { display: flex; gap: 16px; flex-wrap: wrap; justify-content: center; }
.demo figure { margin: 0; text-align: center; }
.demo canvas { display: block; image-rendering: pixelated; background: var(--canvas); border: 2px solid var(--ink); margin: 0 auto 6px; max-width: 100%; }
.demo figcaption { font-size: .85rem; color: var(--ink-soft); max-width: 240px; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 14px; }

.feedback { margin-top: 14px; border: 2px dashed var(--rule); padding: 12px 14px; min-height: 64px; }
.feedback h3 { margin-bottom: .4em; }
.feedback ul { margin: 0; padding: 0; list-style: none; }
.feedback li { padding-left: 26px; position: relative; margin: 6px 0; }
.feedback li::before { position: absolute; left: 0; top: 0; font-weight: 700; }
.feedback li.good::before { content: "✓"; color: var(--good); }
.feedback li.fix::before { content: "●"; color: var(--fix); }
.feedback li.hint::before { content: "→"; color: var(--warn); }
.feedback.complete { border-style: solid; border-color: var(--good); }

/* ---------- pixel editor ---------- */
.ed { display: grid; gap: 12px; }
.ed-bar { display: flex; flex-wrap: wrap; gap: 8px 14px; align-items: center; }
.ed-group { display: flex; flex-wrap: wrap; gap: 6px; }
.ed-main { display: flex; flex-wrap: wrap; gap: 16px; align-items: flex-start; }
.ed-stagewrap { flex: 1 1 260px; min-width: 0; }
.ed-stage {
  position: relative; margin: 0 auto; line-height: 0; background: var(--canvas);
  border: 2px solid var(--ink); box-sizing: content-box; /* so width = exact pixels * zoom */
  touch-action: none; cursor: crosshair; user-select: none; -webkit-user-select: none;
}
.ed-layer { position: absolute; left: 0; top: 0; width: 100%; height: 100%; image-rendering: pixelated; pointer-events: none; }
.ed-layer.hl { animation: pulse 1.1s steps(2, jump-none) infinite; }
@keyframes pulse { 50% { opacity: .45; } }
@media (prefers-reduced-motion: reduce) { .ed-layer.hl { animation: none; } }
.ed-side { flex: 0 0 auto; width: min(100%, 200px); }
.ed-side h3 { font-size: .8rem; margin-bottom: 8px; color: var(--ink-soft); }
.ed-palette { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; max-height: 300px; overflow: auto; padding: 3px; }
.ed-palette.big { grid-template-columns: repeat(8, minmax(0, 1fr)); gap: 3px; overflow-x: hidden; }
.ed-palette.big .sw { min-height: 0; border-width: 1px; }
.ed-palette.big .sw span { display: none; }   /* too small for the number badge */
.sw { position: relative; aspect-ratio: 1; min-height: 28px; min-width: 0; background: var(--c); border: 2px solid var(--ink); border-radius: 2px; cursor: pointer; padding: 0; }
.sw[aria-pressed="true"] { outline: 3px solid var(--accent); outline-offset: 1px; }
.sw span { position: absolute; left: 2px; top: 0; font: 700 .6rem/1.4 var(--font-body); color: #fff; text-shadow: 0 0 2px #000, 0 0 2px #000; }
/* lesson-specific live previews (silhouette, tiling) live under the palette */
.preview { margin-top: 16px; }
.preview h3 { font-size: .8rem; margin: 0 0 6px; color: var(--ink-soft); }
.preview canvas { display: block; image-rendering: pixelated; background: var(--canvas); border: 2px solid var(--ink); max-width: 100%; height: auto; margin-bottom: 6px; }
.preview .note { margin: 0 0 10px; font-size: .8rem; color: var(--ink-soft); line-height: 1.3; }
.preview label { font-size: .85rem; display: flex; gap: 6px; align-items: center; margin-bottom: 8px; }
.slot-labels { display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; margin: 6px auto 0; max-width: 100%; }
.slot-labels span { font: 700 .65rem var(--font-head); text-align: center; color: var(--ink-soft); }
.map-preview { margin-top: 14px; }
.ed-status { margin: 0; font-size: .85rem; color: var(--ink-soft); min-height: 1.4em; }
.ed select { font: inherit; font-size: .9rem; background: var(--card); color: var(--ink); border: 2px solid var(--ink); border-radius: 4px; padding: 8px; min-height: 40px; }
.ed-bar::-webkit-scrollbar { display: none; }

@media (max-width: 560px) {
  body { font-size: 17px; }
  .card { padding: 14px; }
  .ed-side { width: 100%; }
  .ed-palette { grid-template-columns: repeat(8, 1fr); }
}