/* Notan: a quiet nonogram. Black, white and grays only; the board is the page.
 * Chrome follows Hexsweeper's sphere: a tiny mono readout at top center and
 * bare line icons in the bottom corners. */

@font-face {
  font-family: "Plex Mono";
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url("./fonts/IBMPlexMono-500.woff2") format("woff2");
}
@font-face {
  font-family: "Plex Sans";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("./fonts/IBMPlexSans-400.woff2") format("woff2");
}

:root {
  color-scheme: light;
  --zoom: 1;
  --bg: #ffffff;
  --ink: #000000;
  --text: #111111;
  --sub: #5e5e5e;
  --done: #737373;
  --line: #d4d4d4;
  --guide: #8f8f8f;
  --frame: #1c1c1c;
  --mark: #8a8a8a;
  --band: rgba(0, 0, 0, 0.05);
  --icon: #262626;
  --scrim: rgba(255, 255, 255, 0.84);
  --mono: "Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --sans: "Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #000000;
    --ink: #ffffff;
    --text: #ededed;
    --sub: #a6a6a6;
    --done: #888888;
    --line: #2f2f2f;
    --guide: #6c6c6c;
    --frame: #e4e4e4;
    --mark: #7c7c7c;
    --band: rgba(255, 255, 255, 0.07);
    --icon: #dddddd;
    --scrim: rgba(0, 0, 0, 0.8);
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
    --bg: #000000;
    --ink: #ffffff;
    --text: #ededed;
    --sub: #a6a6a6;
    --done: #888888;
    --line: #2f2f2f;
    --guide: #6c6c6c;
    --frame: #e4e4e4;
    --mark: #7c7c7c;
    --band: rgba(255, 255, 255, 0.07);
    --icon: #dddddd;
    --scrim: rgba(0, 0, 0, 0.8);
}

*, *::before, *::after { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

.sr-only {
  position: absolute !important;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

button { font: inherit; color: inherit; }

/* ---------- top readout ---------- */
.hud {
  position: fixed;
  top: max(6px, env(safe-area-inset-top));
  left: 50%;
  transform: translateX(-50%);
  z-index: 5;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  font: 500 calc(13px * var(--zoom))/1 var(--mono);
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--sub);
  white-space: nowrap;
}
.hud svg { width: 14px; height: 14px; flex: none; }
.hud-lvl {
  appearance: none;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  min-height: 44px;
  padding: 0 10px;
  border: 0;
  border-radius: 0;
  background: none;
  color: var(--sub);
  font: inherit;
  cursor: pointer;
  touch-action: manipulation;
}
.hud-lvl:hover { color: var(--text); }
.hud-time { display: inline-flex; align-items: center; gap: 0.4rem; padding: 0 10px; min-width: 6ch; }

/* ---------- board ---------- */
.board {
  position: absolute;
  --cell: 32px;
  --f: 13px;
  --cw: 40px;
  --ch: 40px;
  --dot: 5px;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
  touch-action: none;
  transition: transform 0.7s cubic-bezier(0.3, 0.7, 0.2, 1);
}
.board.instant, .board.instant * , .board.instant *::before, .board.instant *::after { transition: none !important; }
.band {
  /* Selection stays on the square; only completed clue numbers dim. */
  display: none;
}
.cursor {
  position: absolute;
  z-index: 3;
  width: var(--cell);
  height: var(--cell);
  border: 2px solid var(--ink);
  box-shadow: 0 0 0 1px var(--bg), inset 0 0 0 1px var(--bg);
  pointer-events: none;
  display: none;
}
.cursor.on { display: block; }
/* Hint: a ring on one square, dashed when the square is wrong, solid when the
 * outlined clue settles it. It pulses three times, then stays until the next move. */
.hint {
  position: absolute;
  z-index: 3;
  width: var(--cell);
  height: var(--cell);
  border: 3px solid var(--ink);
  box-shadow: 0 0 0 1px var(--bg), inset 0 0 0 1px var(--bg);
  pointer-events: none;
  display: none;
}
.hint.on { display: block; animation: hint-pulse 1.2s ease-in-out 3; }
.hint.wrong { border-style: dashed; }
@keyframes hint-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.15; }
}
.clue.hinted { outline: 2px solid var(--ink); outline-offset: -2px; }

.grid { position: relative; z-index: 1; }
.gr { display: flex; }
.corner { flex: none; width: var(--cw); height: var(--ch); }

.clue {
  flex: none;
  display: flex;
  font: 500 var(--f)/1.18 var(--mono);
  font-variant-numeric: tabular-nums;
  color: var(--text);
  transition: color 0.3s, opacity 0.5s;
  position: relative;
}
.cc {
  width: var(--cell);
  height: var(--ch);
  flex-direction: column;
  justify-content: flex-end;
  align-items: center;
  padding-bottom: calc(var(--f) * 0.4);
}
.rc {
  width: var(--cw);
  height: var(--cell);
  justify-content: flex-end;
  align-items: center;
  gap: calc(var(--f) * 0.5);
  padding-right: calc(var(--f) * 0.55);
}
.clue.ok { color: var(--done); }
/* Each number fades on its own once its run is finished, and pops once as it does. */
.clue span { display: inline-block; transition: color 0.3s; }
.clue span.n-done { color: var(--done); text-decoration: line-through; text-decoration-thickness: 2px; }
.clue span.pop { animation: clue-pop 0.45s ease-out; }
@keyframes clue-pop {
  0% { transform: scale(1); }
  40% { transform: scale(1.4); color: var(--text); }
  100% { transform: scale(1); }
}
/* A line that can't work as marked gets a short dashed tick beside it. */
.clue.bad::after {
  content: "";
  position: absolute;
  border: 0 dashed var(--text);
}
.cc.bad::after { left: 25%; right: 25%; bottom: 2px; border-bottom-width: 1px; }
.rc.bad::after { top: 25%; bottom: 25%; right: 2px; border-right-width: 1px; }

.cell {
  flex: none;
  position: relative;
  width: var(--cell);
  height: var(--cell);
  --guide-x: 0px;
  --guide-y: 0px;
  --lt: transparent;
  --ll: transparent;
  --lr: var(--line);
  --lb: var(--line);
  box-shadow:
    inset calc(-1px - var(--guide-x)) 0 0 var(--lr),
    inset 0 calc(-1px - var(--guide-y)) 0 var(--lb),
    inset 1px 0 0 var(--ll),
    inset 0 1px 0 var(--lt);
  outline: none;
  cursor: pointer;
  transition: box-shadow 0.6s;
}
.cell.gx { --lr: var(--guide); --guide-x: 1px; }
.cell.gy { --lb: var(--guide); --guide-y: 1px; }
.cell.t { --lt: var(--frame); }
.cell.l { --ll: var(--frame); }
.cell.rt { --lr: var(--frame); }
.cell.bt { --lb: var(--frame); }
.cell::before {
  content: "";
  position: absolute;
  left: 0; top: 0; right: 1px; bottom: 1px;
  background: var(--ink);
  transform: scale(0);
  transition: transform 0.12s ease-out, right 0.6s, bottom 0.6s, top 0.6s, left 0.6s;
}
.cell.t::before { top: 1px; }
.cell.l::before { left: 1px; }
.cell.ink::before { transform: scale(1); }
.cell.gx::before { right: 0; box-shadow: inset -2px 0 var(--bg); }
.cell.gy::before { bottom: 0; box-shadow: inset 0 -2px var(--bg); }
.cell.gx.gy::before { box-shadow: inset -2px 0 var(--bg), inset 0 -2px var(--bg); }
.board.solved .cell::before { box-shadow: none; }
.cell::after {
  content: "";
  position: absolute;
  left: 50%; top: 50%;
  width: var(--dot); height: var(--dot);
  margin: calc(var(--dot) / -2) 0 0 calc(var(--dot) / -2);
  border-radius: 50%;
  background: var(--mark);
  opacity: 0;
  transition: opacity 0.12s;
}
.cell.mark::after { opacity: 1; }
/* Level 1, first visit: a faint fill grows and fades in one square until the first move. */
.cell.nudge::before { animation: nudge 1.8s ease-in-out 0.2s infinite; }
@keyframes nudge {
  0%, 100% { transform: scale(0); opacity: 0.28; }
  50% { transform: scale(0.62); opacity: 0.28; }
}

/* Solved: the lines, marks and clues go; the picture stays and moves to center. */
.board { transform-origin: 0 0; }
.board.solved { --line: transparent; --guide: transparent; --frame: transparent; transform: var(--solved); }
.board.solved .cell { cursor: default; }
/* Fills overlap by a pixel so the scaled picture shows no seams. */
.board.solved .cell::before { top: 0; left: 0; right: -1px; bottom: -1px; }
.board.solved .cell::after,
.board.solved .clue,
.board.solved .band,
.board.solved .cursor,
.board.solved .hint { opacity: 0; }

.caption {
  position: absolute;
  left: 0; right: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  opacity: 0;
  transition: opacity 0.6s 0.5s;
  pointer-events: none;
}
.caption[hidden] { display: none; }
.caption.show { opacity: 1; pointer-events: auto; }
.caption .share-btn { min-height: 36px; }
.caption .share-btn[hidden] { display: none; }
.caption p { margin: 0; font: 500 calc(13px * var(--zoom))/1.3 var(--mono); letter-spacing: 0.04em; color: var(--sub); }

/* ---------- corner icons ---------- */
.bar {
  position: fixed;
  left: max(6px, env(safe-area-inset-left));
  right: max(6px, env(safe-area-inset-right));
  bottom: max(6px, env(safe-area-inset-bottom));
  z-index: 5;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  pointer-events: none;
}
.group { display: flex; gap: 2px; pointer-events: auto; }
.ib {
  appearance: none;
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  padding: 0;
  border: 0;
  border-radius: 0;
  background: none;
  color: var(--icon);
  cursor: pointer;
  touch-action: manipulation;
  transition: opacity 0.15s, transform 0.1s;
}
.ib svg { width: 24px; height: 24px; }
.ib:active { transform: scale(0.94); }
.ib[aria-disabled="true"] { opacity: 0.32; cursor: default; }
.ib:focus-visible,
.hud-lvl:focus-visible,
.lv:focus-visible,
.text-action:focus-visible,
.size-choice:focus-visible,
.sheet-x:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}
@media (hover: hover) {
  .ib:hover:not([aria-disabled="true"]) { background: var(--band); }
}


/* Sheets: the header stays put; only the content scrolls. */
dialog.sheet {
  width:min(calc(32rem * var(--zoom)),calc(100vw - 16px));
  max-width:none; max-height:calc(100dvh - 16px - env(safe-area-inset-top) - env(safe-area-inset-bottom));
  height:fit-content; padding:0; margin:auto; border:1px solid var(--frame);
  border-radius:0; background:var(--bg); color:var(--text); overflow:hidden;
}
dialog.sheet[open] { display:block; }
dialog.sheet::backdrop { background:var(--scrim); }
.sheet-in { max-height:calc(100dvh - 18px - env(safe-area-inset-top) - env(safe-area-inset-bottom)); display:flex; flex-direction:column; min-height:0; width:100%; font:400 calc(16px * var(--zoom))/1.45 var(--sans); }
.sheet-head { display:flex; flex:none; align-items:center; justify-content:space-between; gap:12px; padding:8px 16px; border-bottom:1px solid var(--line); }
.sheet-head form { margin:0; }
.sheet h2 { margin:0; font:500 calc(16px * var(--zoom))/1.3 var(--mono); }
.sheet-x { display:grid; place-items:center; width:44px; height:44px; padding:0; border:0; background:none; color:var(--text); cursor:pointer; }
.sheet-x svg { width:24px; height:24px; }
.sheet-body { min-height:0; overflow:auto; overscroll-behavior:contain; padding:20px 24px; scroll-padding:12px; }
.sheet p { margin:0 0 16px; }
.sheet h3 { margin:0 0 8px; font:500 1em/1.4 var(--sans); }
.sheet section + section { border-top:1px solid var(--line); margin-top:20px; padding-top:20px; }
.sheet .sizes { display:flex; flex-wrap:wrap; gap:4px; }
.text-action,.size-choice,.lv {
  appearance:none; min-width:44px; min-height:44px; padding:8px 12px; border:1px solid var(--line); border-radius:0;
  background:none; color:var(--text); font:500 calc(16px * var(--zoom))/1.3 var(--mono); cursor:pointer; touch-action:manipulation;
}
.size-choice { padding:8px; border-color:transparent; color:var(--sub); }
.size-choice[aria-pressed="true"],.text-action[aria-pressed="true"] { border-color:var(--frame); color:var(--ink); }
.text-action:disabled { opacity:.45; cursor:default; }
.text-action[aria-disabled="true"] { color:var(--sub); cursor:default; }
.text-action:hover,.size-choice:hover,.lv:hover { background:var(--band); }
.sheet :is(button,a,summary,[role="gridcell"]):focus-visible { outline:2px solid var(--ink); outline-offset:2px; }
.wide-action { margin-top:12px; }
.setting-row { display:flex; align-items:center; justify-content:space-between; flex-wrap:wrap; gap:8px 16px; margin-top:8px; }
#theme-btn { display:flex; align-items:center; gap:8px; }
#theme-btn svg { width:20px; height:20px; flex:none; }
.practice-tools { display:flex; flex-wrap:wrap; justify-content:center; gap:8px; }
.practice-tools form { margin:0; }
.sheet-foot { border-top:1px solid var(--line); padding-top:12px; margin-top:20px; }
.foot-btn { display:inline-flex; align-items:center; min-height:44px; font:400 16px/1.4 var(--sans); color:var(--sub); text-underline-offset:3px; background:none; border:0; cursor:pointer; }
.lv-grid { list-style:none; margin:0 0 20px; padding:0; display:grid; grid-template-columns:repeat(auto-fill,minmax(max(44px,calc(40px * var(--zoom))),1fr)); gap:4px; }
.lv { width:100%; padding:8px 0; border-color:transparent; color:var(--sub); }
.lv.done { color:var(--ink); }
.lv[aria-current="true"] { border-color:var(--frame); }
.lesson { padding-top:4px; }
.lesson-heading { display:flex; justify-content:space-between; align-items:baseline; gap:12px; }
#lesson-count { color:var(--sub); white-space:nowrap; }
/* The clue sits in the left margin, as row clues do on the board, so the strip stays centered over its tools. */
.practice-line { display:grid; grid-template-columns:1fr min(calc(100% - 5em),calc(280px * var(--zoom))) 1fr; justify-content:center; align-items:center; column-gap:12px; row-gap:8px; margin:20px 0 12px; }
#practice-clue { grid-column:1; justify-self:end; font:500 calc(20px * var(--zoom))/1.3 var(--mono); text-align:right; white-space:nowrap; }
#practice { grid-column:2; width:100%; touch-action:none; user-select:none; }
#practice-reset[hidden] { display:none; }
#practice-row { display:grid; grid-template-columns:repeat(5,1fr); }
.practice-cell { aspect-ratio:1; min-width:44px; min-height:44px; padding:0; border:1px solid var(--guide); border-right:0; position:relative; background:var(--bg); touch-action:none; }
.practice-cell:last-child { border-right:1px solid var(--guide); }
.practice-cell.ink { background:var(--ink); }
.practice-cell.mark::after { content:""; position:absolute; width:14%; height:14%; top:43%; left:43%; border-radius:50%; background:var(--mark); }
.practice-key { display:flex; flex-wrap:wrap; justify-content:center; gap:8px 16px; font-size:16px; color:var(--sub); }
.practice-key span { display:inline-flex; align-items:center; gap:6px; }
.practice-key i { display:inline-block; width:16px; height:16px; border:1px solid var(--guide); position:relative; }
.practice-key .filled { background:var(--ink); }
.practice-key .empty::after { content:""; position:absolute; width:4px; height:4px; border-radius:50%; background:var(--mark); top:5px; left:5px; }
#practice-feedback { margin:8px 0 10px; min-height:1.45em; color:var(--sub); text-align:center; }
.lesson-nav { display:flex; justify-content:space-between; flex-wrap:wrap; gap:8px; }
#lesson-possibilities { grid-column:2; margin:0; width:100%; }
#lesson-possibilities:not([hidden]) { display:grid; gap:8px; }
.possibility { display:grid; grid-template-columns:repeat(5,1fr); height:calc(18px * var(--zoom)); border:1px solid var(--guide); }
.possibility i { border-right:1px solid var(--guide); }
.possibility i:last-child { border-right:0; }
.possibility i.on { background:var(--ink); }
.rules { border-top:1px solid var(--line); margin-top:20px; }
.rules summary { min-height:44px; padding:12px 0; cursor:pointer; }
.rules p { color:var(--sub); margin:0 0 10px; font-size:calc(15px * var(--zoom)); line-height:1.45; }
.rules b { color:var(--text); font-weight:500; }
@media(max-width:480px) { .sheet-body { padding:16px; } .sheet-head { padding:8px 12px; } }
@media(prefers-reduced-motion:reduce) { *,*::before,*::after { transition:none!important; animation:none!important; } .cell.nudge::before { opacity:.2; transform:scale(.62); } }
@media(forced-colors:active) { :root { --ink:CanvasText; --text:CanvasText; --bg:Canvas; --line:GrayText; --guide:GrayText; --frame:CanvasText; --mark:CanvasText; --done:GrayText; --icon:ButtonText; } .board,.practice-cell,.possibility { forced-color-adjust:none; } .cursor,.hint { border-color:Highlight; } }

/* Quiet rules beside locked clues, independent of completion and conflict ticks. */
.clue.locked::before, .eg-clue.locked::before { content: ""; position: absolute; background: var(--sub); }
.rc.locked::before { width: 2px; right: 3px; top: 25%; bottom: 25%; }
.cc.locked::before { height: 2px; bottom: 3px; left: 25%; right: 25%; }
.eg-clue.locked { position: relative; color: var(--done); }
.eg-clue.locked::before { width: 2px; right: -5px; top: 0; bottom: 0; }

#mode-btn[aria-pressed="true"] { background: var(--ink); color: var(--bg); }
/* Controls, at a glance (Luke, 2026-10-06: "don't need much more text whatsoever"). */
.controls { margin:16px 0 0; padding-top:12px; border-top:1px solid var(--line); display:grid; gap:6px; }
.controls div { display:flex; flex-wrap:wrap; gap:0 8px; }
.controls dt { color:var(--text); }
.controls dt::after { content:" \2014"; color:var(--sub); }
.controls dd { margin:0; color:var(--sub); }

/* The possibility bars keep their space in every lesson, so the sheet never changes height. */
#lesson-possibilities { display: grid !important; }
#lesson-possibilities.is-off { visibility: hidden; }

/* Lesson tasks reserve two lines, so a one-line task does not shrink the sheet. */
#lesson-task { min-height: 2lh; }

/* Holding a lesson square marks it; it must not start a text selection or callout. */
#help { -webkit-user-select:none; user-select:none; -webkit-touch-callout:none; }