:root {
  --bg: #0b0b0d;
  --panel: #1c1c1f;
  --panel-alt: #2a2a30;
  --ink: #f2f2f4;
  --muted: #9a9aa1;
  --border: #333338;
  --accent: #e4e4e7;
  --accent2: #d4d4d8;
  --accent3: #cfcfd4;
  --accent4: #ffffff;
  --good: #4ade80;
  --bad: #f87171;
  --radius: 20px;
}

* { box-sizing: border-box; }

a { color: var(--accent4); }

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Segoe UI", system-ui, -apple-system, Verdana, sans-serif;
  /* Math/science doodles (hand-drawn SVG) layered over the gradient. */
  background: url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22420%22%20height%3D%22420%22%20viewBox%3D%220%200%20420%20420%22%20fill%3D%22none%22%20stroke%3D%22%23232329%22%20stroke-width%3D%222%22%20stroke-linecap%3D%22round%22%20stroke-linejoin%3D%22round%22%3E%20%3Cg%20transform%3D%22translate%2860%2060%29%20rotate%28-8%29%22%3E%20%3Ctext%20x%3D%220%22%20y%3D%229%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2228%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3E%26%23960%3B%3C%2Ftext%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28180%2056%29%22%3E%20%3Cpath%20d%3D%22M-14%200%20L-9%2010%20L-2%20-12%20H14%22%2F%3E%3Cpath%20d%3D%22M-2%20-8%20H12%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28300%2060%29%20rotate%286%29%22%3E%20%3Ccircle%20cx%3D%220%22%20cy%3D%22-2%22%20r%3D%2210%22%2F%3E%3Cpath%20d%3D%22M-5%206%20Q0%202%205%206%22%2F%3E%20%3Cpath%20d%3D%22M-4%2010%20H4%20M-3%2014%20H3%22%2F%3E%3Cpath%20d%3D%22M-3%20-4%20L0%200%20L3%20-4%20M0%200%20V6%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28390%2070%29%22%3E%20%3Ctext%20x%3D%220%22%20y%3D%227%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2222%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3E%26%238734%3B%3C%2Ftext%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%2880%20170%29%20rotate%284%29%22%3E%20%3Cpath%20d%3D%22M-12%2014%20L0%20-16%20L12%2014%20Z%22%2F%3E%3Cpath%20d%3D%22M4%2014%20V9%20H9%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28200%20150%29%22%3E%20%3Cpath%20d%3D%22M-18%208%20A18%2018%200%200%201%2018%208%20Z%22%2F%3E%20%3Cpath%20d%3D%22M-13%203%20L-11%205%20M-8%20-3%20L-6%20-1%20M0%20-6%20V-3%20M8%20-3%20L6%20-1%20M13%203%20L11%205%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28320%20160%29%20rotate%28-6%29%22%3E%20%3Ccircle%20cx%3D%220%22%20cy%3D%22-12%22%20r%3D%223%22%2F%3E%20%3Cpath%20d%3D%22M-2%20-9%20L-10%2014%20M2%20-9%20L10%2014%22%2F%3E%3Cpath%20d%3D%22M-7%206%20Q0%2010%207%206%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28390%20200%29%22%3E%20%3Ctext%20x%3D%220%22%20y%3D%228%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2224%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3E%26%23931%3B%3C%2Ftext%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%2860%20300%29%22%3E%20%3Ccircle%20cx%3D%220%22%20cy%3D%220%22%20r%3D%223%22%2F%3E%20%3Cellipse%20cx%3D%220%22%20cy%3D%220%22%20rx%3D%2217%22%20ry%3D%227%22%2F%3E%20%3Cellipse%20cx%3D%220%22%20cy%3D%220%22%20rx%3D%2217%22%20ry%3D%227%22%20transform%3D%22rotate%2860%29%22%2F%3E%20%3Cellipse%20cx%3D%220%22%20cy%3D%220%22%20rx%3D%2217%22%20ry%3D%227%22%20transform%3D%22rotate%28-60%29%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28170%20260%29%20rotate%285%29%22%3E%20%3Cpath%20d%3D%22M-4%20-16%20H4%20M-3%20-16%20V-6%20L8%2010%20Q10%2014%206%2014%20H-6%20Q-10%2014%20-8%2010%20L3%20-6%20V-16%22%2F%3E%20%3Cpath%20d%3D%22M-4%206%20H4%22%2F%3E%3Ccircle%20cx%3D%220%22%20cy%3D%2210%22%20r%3D%221%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28280%20260%29%20rotate%2830%29%22%3E%20%3Cpath%20d%3D%22M-5%208%20Q-9%204%20-5%20-2%20Q0%20-10%200%20-16%20Q0%20-10%205%20-2%20Q9%204%205%208%22%2F%3E%20%3Ccircle%20cx%3D%220%22%20cy%3D%22-2%22%20r%3D%223%22%2F%3E%20%3Cpath%20d%3D%22M-5%208%20L-8%2013%20M5%208%20L8%2013%20M0%209%20V14%22%2F%3E%20%3Cpath%20d%3D%22M-5%208%20Q0%2011%205%208%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%2880%20390%29%20rotate%28-4%29%22%3E%20%3Crect%20x%3D%22-24%22%20y%3D%22-5%22%20width%3D%2248%22%20height%3D%2210%22%20rx%3D%221%22%2F%3E%20%3Cpath%20d%3D%22M-16%20-5%20V0%20M-8%20-5%20V-1%20M0%20-5%20V0%20M8%20-5%20V-1%20M16%20-5%20V0%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28200%20380%29%22%3E%20%3Cpath%20d%3D%22M-8%20-14%20Q-14%20-14%20-14%20-6%20Q-14%202%20-8%202%20L-8%2010%20H-2%20L-2%202%20M-8%20-14%20H-2%20V-6%22%2F%3E%20%3Cpath%20d%3D%22M8%20-14%20Q14%20-14%2014%20-6%20Q14%202%208%202%20L8%2010%20H2%20L2%202%20M8%20-14%20H2%20V-6%22%2F%3E%20%3Cpath%20d%3D%22M-8%20-14%20V-18%20M8%20-14%20V-18%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28310%20370%29%22%3E%20%3Ccircle%20cx%3D%220%22%20cy%3D%22-4%22%20r%3D%229%22%2F%3E%3Cpath%20d%3D%22M-4%205%20H4%20M-3%209%20H3%20M-2%2013%20H2%22%2F%3E%20%3Cpath%20d%3D%22M-3%20-6%20Q0%20-2%200%205%20M3%20-6%20Q0%20-2%200%205%22%2F%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28390%20320%29%20rotate%28-8%29%22%3E%20%3Ctext%20x%3D%220%22%20y%3D%226%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2217%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3Ex%26%23178%3B%3C%2Ftext%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28140%20320%29%20rotate%286%29%22%3E%20%3Ctext%20x%3D%220%22%20y%3D%226%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2215%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3E2%2B2%3C%2Ftext%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28260%20100%29%20rotate%28-5%29%22%3E%20%3Ctext%20x%3D%220%22%20y%3D%226%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2217%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3E%26%23247%3B%3C%2Ftext%3E%20%3Ctext%20x%3D%2220%22%20y%3D%226%22%20text-anchor%3D%22middle%22%20font-family%3D%22Trebuchet%20MS%2C%20sans-serif%22%20font-size%3D%2215%22%20fill%3D%22%23232329%22%20stroke%3D%22none%22%3E%26%23215%3B%3C%2Ftext%3E%20%3C%2Fg%3E%20%3Cg%20transform%3D%22translate%28340%20300%29%22%3E%20%3Ccircle%20cx%3D%220%22%20cy%3D%220%22%20r%3D%228%22%2F%3E%3Cellipse%20cx%3D%220%22%20cy%3D%220%22%20rx%3D%2216%22%20ry%3D%225%22%20transform%3D%22rotate%28-18%29%22%2F%3E%20%3C%2Fg%3E%20%3C%2Fsvg%3E") repeat, linear-gradient(160deg, #0b0b0d, #131316 60%, #0b0b0d);
  background-size: 210px 210px, auto;
  color: var(--ink);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px 64px;
  /* Looser than the browser default (~1.2) — trialed on shapes.html first
     (see PROJECT-NOTES.md), then rolled out everywhere: dense line spacing
     read as "wall of text, skip it" to an 8-year-old even when the actual
     word count was fine. */
  line-height: 1.6;
}

header {
  text-align: center;
  margin-bottom: 24px;
}

header h1 {
  font-size: clamp(2rem, 6vw, 3.2rem);
  margin: 0 0 8px;
  color: var(--accent4);
  text-shadow: 2px 2px 0 rgba(0, 0, 0, 0.6);
}

header p {
  font-size: 1.1rem;
  margin: 0;
  opacity: 0.8;
}

nav {
  display: flex;
  gap: 12px;
  margin: 16px 0 32px;
  flex-wrap: wrap;
  justify-content: center;
}

nav a {
  text-decoration: none;
  font-weight: bold;
  font-size: 1.1rem;
  padding: 10px 20px;
  border-radius: 999px;
  background: var(--panel);
  border: 1px solid var(--border);
  color: var(--ink);
  box-shadow: 0 4px 0 rgba(0,0,0,0.4);
  transition: transform 0.1s ease;
}

nav a:hover, nav a:focus-visible {
  transform: translateY(-2px);
}

nav a.active {
  background: var(--accent4);
  border-color: var(--accent4);
  color: var(--bg);
}

main {
  width: 100%;
  max-width: 720px;
}

main.wide {
  max-width: min(1200px, 95vw);
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
}

.cards + .section-title {
  margin-top: 40px;
}

.section-title {
  text-align: center;
  font-size: 1.4rem;
  margin: 0 0 20px;
  color: var(--accent4);
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  text-decoration: none;
  color: var(--ink);
  box-shadow: 0 6px 0 rgba(0,0,0,0.4);
  transition: transform 0.15s ease;
}

.card:hover, .card:focus-visible {
  transform: translateY(-4px) rotate(-1deg);
}

.card .emoji {
  font-size: 3rem;
  display: block;
  margin-bottom: 8px;
}

.card h2 {
  margin: 0 0 6px;
}

.card p {
  margin: 0;
  opacity: 0.75;
  font-size: 0.95rem;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  box-shadow: 0 6px 0 rgba(0,0,0,0.4);
  margin-bottom: 24px;
}

.op-picker {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 20px;
}

.op-picker button {
  font-size: 1.4rem;
  padding: 10px 18px;
  border-radius: 14px;
  border: 3px solid transparent;
  background: var(--panel-alt);
  color: var(--ink);
  cursor: pointer;
  font-family: inherit;
}

.op-picker button.active {
  border-color: var(--accent4);
  background: #303036;
}

.op-picker.disabled button {
  opacity: 0.5;
  pointer-events: none;
}

.picker-hint {
  text-align: center;
  margin: 0 0 10px;
  opacity: 0.65;
  font-size: 0.9rem;
}

.start-panel {
  text-align: center;
  margin-bottom: 20px;
}

.start-panel p {
  font-size: 1.2rem;
  margin: 0 0 14px;
}

.start-panel button {
  font-size: 1.3rem;
  padding: 12px 28px;
  border-radius: 14px;
  border: none;
  background: var(--accent4);
  color: var(--bg);
  cursor: pointer;
  font-family: inherit;
}

.problem {
  text-align: center;
}

.problem .expr {
  font-size: clamp(2.5rem, 10vw, 4rem);
  font-weight: bold;
  margin: 10px 0 20px;
}

.problem input[type="number"] {
  font-size: 2rem;
  width: 140px;
  text-align: center;
  padding: 8px;
  border-radius: 12px;
  border: 3px solid var(--accent4);
  background: var(--panel-alt);
  color: var(--ink);
  font-family: inherit;
}

.problem button {
  font-size: 1.3rem;
  padding: 10px 24px;
  margin-left: 10px;
  border-radius: 14px;
  border: none;
  background: var(--accent4);
  color: var(--bg);
  cursor: pointer;
  font-family: inherit;
}

.feedback {
  min-height: 2.4rem;
  font-size: 1.5rem;
  font-weight: bold;
  margin-top: 16px;
}

.feedback.good { color: var(--good); }
.feedback.bad { color: var(--bad); }

.stats {
  display: flex;
  justify-content: center;
  gap: 28px;
  margin-top: 20px;
  font-size: 1.1rem;
}

.stats b {
  display: block;
  font-size: 1.6rem;
}

.stat-total {
  /* The "/ 400" belongs to the number, not under it — it used to sit outside
     the block-level <b> and so landed on a third line of its own, which on a
     phone is a whole line of scarce height spent on a slash. */
  font-size: 1rem;
  opacity: 0.7;
}

.grid12 {
  display: grid;
  /* 21 columns: the real 1-20 grid, plus a fixed-width 21st column,
     flush against the 20th, for the 30x30 cell — see
     renderGrid()/renderJoke30x30()
     in multiplication-table.js for why every cell is explicitly placed
     rather than auto-flowed. Capped at max-width so the columns can't
     grow arbitrarily large on a wide screen — they did, once, when the
     page's main was widened for more panel breathing room, and the
     whole table got tall enough to need vertical scrolling instead. */
  grid-template-columns: repeat(20, minmax(26px, 1fr)) 34px;
  max-width: 700px;
  margin: 16px auto 0;
  gap: 2px;
  font-size: 0.8rem;
  overflow-x: auto;
  padding-bottom: 6px;
}

/* Both big tables are wider than a phone and scroll sideways inside their
   box, and nothing said so: measured at 390px wide, the multiplication grid
   shows 11 of its 21 columns and the periodic table 8 of its 18 groups. A
   phone draws its scrollbar as an overlay that only appears WHILE you drag,
   and ignores ::-webkit-scrollbar entirely, so styling the bar is not the
   fix — these fades are. The wrapper is the fixed frame; the scroller inside
   it moves. Toggled by the page script rather than always on: a permanent
   fog over the first and last column would be worse than the problem it
   solves.

   Both fades sit ON TOP of the cells, so they must be var(--panel) — the
   colour of the box behind the table — to read as "the table runs out of
   room here" rather than as a grey stripe. */
.table-scroller {
  position: relative;
}

.table-scroller::before,
.table-scroller::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 24px;
  pointer-events: none;
  z-index: 3;
  opacity: 0;
  transition: opacity 0.15s;
}

.table-scroller::before {
  left: 0;
  background: linear-gradient(to right, var(--panel), transparent);
}

.table-scroller::after {
  right: 0;
  background: linear-gradient(to left, var(--panel), transparent);
}

.table-scroller.can-left::before,
.table-scroller.can-right::after {
  opacity: 1;
}

/* Desktop only — a phone ignores all of this (see above). Harmless there,
   and it colours the bar on a narrow desktop window, which is the one place
   these tables scroll on a mouse-driven browser. */
.grid12::-webkit-scrollbar,
.ptable-wrap::-webkit-scrollbar {
  height: 6px;
}

.grid12::-webkit-scrollbar-track,
.ptable-wrap::-webkit-scrollbar-track {
  background: var(--panel-alt);
  border-radius: 3px;
}

.grid12::-webkit-scrollbar-thumb,
.ptable-wrap::-webkit-scrollbar-thumb {
  background: var(--muted);
  border-radius: 3px;
}

.grid12,
.ptable-wrap {
  scrollbar-width: thin;
  scrollbar-color: var(--muted) var(--panel-alt);
}

/* Only shown on a narrow screen held upright — see the media query near the
   bottom of this file. Landscape needs no hint: at 844px both tables fit
   whole, which is exactly what the second half of the sentence is for. */
.swipe-hint {
  display: none;
  margin: 10px 0 0;
  text-align: center;
  font-size: 0.85rem;
  color: var(--muted);
}

.grid12 div {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  background: var(--panel-alt);
  /* White text with a black outline reads against every one of the
     rainbow background colors (see multiplication-table.js) without
     needing a per-number light/dark text lookup. */
  color: #ffffff;
  text-shadow: -1px -1px 0 #000, 1px -1px 0 #000, -1px 1px 0 #000, 1px 1px 0 #000;
}

.grid12 div.dim {
  /* Selection is shown by darkening everything EXCEPT the selected
     row/column, not by outlining the selected cells — a ring around the
     marked cells had the same problem as plain-color rings always do:
     no single ring color contrasts against all ten-plus rainbow
     backgrounds at once (see git history). Dimming has no such problem —
     it darkens every cell's own color by the same amount, so the
     selected row/column simply reads as "the bright ones" against a
     uniformly muted rest of the grid, whatever colors are involved. */
  filter: brightness(0.35);
}

.grid12 div.joke-cell {
  /* Elton's "30 times table" joke row: sits below the regular 1-20 grid,
     so it's not one of the rainbow-colored gnomon cells above (see
     NUMBER_COLORS in multiplication-table.js) — flat yellow instead, and
     half the height so it visually reads as a bonus strip, not another
     real row. */
  aspect-ratio: 2 / 1;
  background: #E6C40C;
  color: #1a1a1a;
  text-shadow: none;
  cursor: pointer;
}

.grid12.quiz-grid {
  /* Quiz mode has no joke row, so no 21st bonus column either — without
     this override the empty reserved column shoves the quiz grid 34px
     off-center compared to the Explore grid above it. */
  grid-template-columns: repeat(20, minmax(26px, 1fr));
}

.quiz-cell-input {
  /* Fills its square exactly; the translucent dark backing keeps the
     white text readable on every rainbow cell color, including the
     white teen/Ten cells. */
  width: 100%;
  height: 100%;
  border: none;
  border-radius: 0;
  padding: 0;
  text-align: center;
  font: inherit;
  color: #fff;
  background: rgba(0, 0, 0, 0.45);
  outline: 2px solid #fff;
  outline-offset: -2px;
}

.grid12 div.quiz-reveal {
  /* The square you got wrong, showing the correct number during the
     pause before the table resets. */
  outline: 3px solid #fff;
  outline-offset: -3px;
  font-weight: 700;
}

.grid12 div.joke-cell-extra {
  /* The 30x30 "diagonal" cell for the joke row — a real grid cell in its
     own dedicated 21st column (see .grid12 above). First cut had a gap
     on its left so it read as hanging off rather than a natural
     continuation; Elton asked for it connected to the 30x20 cell
     instead, flush against it like the rest of the row. */
}

.number-picker {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 16px;
}

.number-picker button {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  background: var(--panel-alt);
  color: var(--ink);
  font-size: 1.1rem;
  font-family: inherit;
  cursor: pointer;
}

.number-picker button.active {
  background: var(--accent4);
  color: var(--bg);
}

.number-picker button.clear-btn {
  width: auto;
  border-radius: 999px;
  padding: 0 18px;
}

.fact {
  margin-bottom: 30px;
}

.fact h3 {
  margin: 0 0 8px;
  color: var(--accent4);
}

.fact p {
  margin: 0;
}

.fact p + p {
  margin-top: 12px;
}

.pi-glyph {
  font-family: Georgia, "Times New Roman", "Liberation Serif", serif;
  font-style: italic;
}

.pi-digits, .equation {
  font-family: "Courier New", monospace;
  font-size: 0.95rem;
  letter-spacing: 1px;
  background: var(--panel-alt);
  border-radius: 10px;
  padding: 10px 12px;
  line-height: 1.6;
}

.pi-digits {
  /* Bigger than the shared .equation size above — Elton asked for the
     digits themselves to read larger now that there are 200 of them
     instead of 100 (see pi.html/pi.js). Sized (measured with Playwright,
     not guessed) so a full row fills ~96% of the box's content width at
     the panel's max size without wrapping — first at 20/row (4 blocks of
     5) that was 2.7rem; Elton then asked for 25/row (5 blocks of 5)
     instead and a bit smaller, which at the same 96%-fill target comes
     out to 2.1rem (a longer row needs a smaller font to still fit). */
  font-size: 2.1rem;
  line-height: 1.5;
  /* If anything ever renders wider than the box (e.g. a stale-cache
     version mix, see the .pi-grid note below), it scrolls inside the box
     instead of bleeding invisibly past both screen edges. */
  overflow-x: auto;
}

/* The reference is a grid of 5-digit <span> blocks (see pi.html), not
   text with hard <br>s: on phones a hard-broken 25-digit row wrapped
   as 2+2+1 blocks, leaving every third visual line a lone dangling
   block. A grid instead drops evenly to 4 columns, then 2, below —
   rows stay uniform at every width.

   Scoped to .pi-grid (a co-class that ships in the SAME pi.html as the
   span markup), NOT bare .pi-digits: the service worker revalidates
   pi.html and style.css independently, so right after a deploy a phone
   can hold new CSS + old HTML for one load — grid rules applied to the
   old <br>-based text turned each 25-digit run into one huge anonymous
   grid item and sprayed digits past both screen edges (seen live on
   Rosie's phone). With the co-class, a version mix just renders in the
   other version's plain-block layout until the next reload. */
.pi-digits.pi-grid {
  display: grid;
  grid-template-columns: repeat(5, max-content);
  justify-content: center;
  justify-content: safe center; /* older browsers keep plain center */
  column-gap: 0.55em;
}

.pi-digits .pi-lead {
  /* The "3." line above the digit blocks. */
  grid-column: 1 / -1;
}

@media (max-width: 719px) {
  /* Breakpoint measured: 5 columns at 2.1rem genuinely need ~720px of
     viewport — at 700px they quietly overhung the box padding by a few
     px on each side (invisible, but real). */
  .pi-digits.pi-grid {
    grid-template-columns: repeat(4, max-content);
    /* Fluid: 20 digits + gaps must fit the viewport minus page/panel/box
       chrome (~130px). Divisor measured with Playwright, same method as
       the 2.1rem above. */
    font-size: min(2.1rem, calc((100vw - 130px) / 14.5));
  }
}

/* Phone layout for the two big tables. Both of them scroll sideways rather
   than shrink: the multiplication grid can't fit 21 columns of up-to-3-digit
   products in 360px (that's ~14px a cell), and shrinking the periodic table
   to fit costs ~16px tiles, which is below what a finger can aim at. So the
   mobile answer here is "make the scrolling obvious", not "make it fit". */
@media (max-width: 719px) and (orientation: portrait) {
  .swipe-hint {
    display: block;
  }
}

@media (max-width: 719px) {
  .elem-detail {
    /* The fact text runs to several lines on a narrow screen, and centring
       left the big symbol floating halfway down beside it. */
    align-items: flex-start;
  }

  .grid12 div {
    /* The typing box floats above its square (see .quiz-cell-input below),
       so the square has to be its containing block. */
    position: relative;
  }

  .quiz-cell-input {
    /* Two mobile-only problems, one fix. A focused input with a computed
       font-size under 16px makes iOS Safari zoom the whole page in — and it
       doesn't reliably zoom back out, which here would leave the page
       scaled over a quiz whose commit path runs on blur. And a 26px box is
       a poor target to type a 3-digit answer into anyway. So: 16px text in
       a box wider than its square, floated over the grid and centred on the
       square that was tapped. It only exists while he's typing, so briefly
       covering the neighbours costs nothing. */
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    width: 48px;
    height: 100%;
    font-size: 16px;
    z-index: 2;
  }

}

@media (max-width: 460px) {
  .pi-digits.pi-grid {
    grid-template-columns: repeat(2, max-content);
    /* Half the digits per row, so the font gets room to grow back. */
    font-size: min(2.1rem, calc((100vw - 130px) / 7.2));
  }
}

.equation {
  display: inline-block;
  font-size: 1.1rem;
}

.prime-check input {
  font-size: 1.5rem;
  width: 220px;
  max-width: 100%;
  text-align: center;
  padding: 8px;
  border-radius: 12px;
  border: 3px solid var(--accent2);
  background: var(--panel-alt);
  color: var(--ink);
  font-family: inherit;
}

.learn-more {
  display: inline-block;
  margin-top: 14px;
  font-weight: bold;
}

#nameForm input, #passwordForm input, .beats-name input {
  font-size: 1.3rem;
  padding: 10px 14px;
  border-radius: 12px;
  border: 3px solid var(--accent4);
  background: var(--panel-alt);
  color: var(--ink);
  font-family: inherit;
  /* An <input> defaults to a ~20-character intrinsic width, which at this
     font size comes out around 302px — wider than the panel's 240px
     content box on a 320px phone. Because body is a centred flex column,
     an over-wide child doesn't just overflow to the right, it bleeds off
     BOTH edges, and the left bleed can't be scrolled to at all. Cap it
     instead; border-box so the padding and 3px border count inside the
     cap rather than pushing back past it. */
  max-width: 100%;
  box-sizing: border-box;
}

#nameForm button, #passwordForm button, .beats-name button {
  font-size: 1.2rem;
  padding: 10px 20px;
  margin-left: 10px;
  border-radius: 14px;
  border: none;
  background: var(--accent4);
  color: var(--bg);
  cursor: pointer;
  font-family: inherit;
}

.player-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 10px 18px;
  margin-bottom: 16px;
  font-size: 1rem;
}

.player-bar a {
  color: var(--accent4);
  font-weight: bold;
}

/* Some tables can't fit a narrow phone no matter what: a column's
   min-content is set by its longest unbreakable word plus its header, and
   si-units' "Metric Prefixes" (Prefix/Symbol/Means/Example) needs 352px
   against a 240px panel at 320px wide. width: 100% doesn't help — a table
   won't shrink below min-content. Rather than shrink the type for an
   8-year-old, let the table scroll inside its own box, same reasoning as
   the .pi-digits note above: bleeding past both screen edges hides the
   left half where nothing can scroll to it. */
.table-scroll {
  overflow-x: auto;
}

.hiscore-table {
  width: 100%;
  border-collapse: collapse;
}

.hiscore-table th, .hiscore-table td {
  text-align: left;
  padding: 8px 10px;
}

.hiscore-table tr:nth-child(odd) td {
  background: var(--panel-alt);
  border-radius: 8px;
}

.hiscore-table td:first-child {
  font-weight: bold;
  width: 2.2em;
}

/* si-units.html's step tables reuse .hiscore-table for the styling, but their
   first column holds a whole quantity ("1 minute"), not a rank number — the
   2.2em rank width above wrapped every single row to two lines on a phone.
   Scoped to the co-class so the actual hiscore boards keep their narrow rank
   column. */
.steps-table td:first-child {
  width: auto;
  white-space: nowrap;
}

.op-tags {
  margin-left: 8px;
  font-size: 0.85rem;
  opacity: 0.65;
  white-space: nowrap;
}

.hiscore-empty {
  opacity: 0.7;
  text-align: center;
  padding: 12px;
}

.offline-note {
  text-align: center;
  opacity: 0.75;
  font-size: 0.9rem;
  margin: 0 0 12px;
}

.prime-result {
  margin-top: 12px;
  font-size: 1.3rem;
  font-weight: bold;
  min-height: 1.6rem;
}

.translator textarea {
  width: 100%;
  font-size: 1.2rem;
  padding: 10px 12px;
  border-radius: 12px;
  border: 3px solid var(--accent4);
  background: var(--panel-alt);
  color: var(--ink);
  font-family: inherit;
  resize: vertical;
}

.code-output {
  font-family: "Courier New", monospace;
  font-size: 1.1rem;
  letter-spacing: 1px;
  background: var(--panel-alt);
  border-radius: 10px;
  padding: 10px 12px;
  margin: 12px 0;
  min-height: 2.6rem;
  line-height: 1.6;
  word-break: break-all;
  white-space: pre-wrap;
}

.code-output.bad {
  color: var(--bad);
  font-family: inherit;
  word-break: normal;
}

/* Secret Agent Missions (elton.html + missions.js) */

/* .picker-hint dims the whole prompt and opacity doesn't un-cascade to a
   child, so the prompt carries no opacity of its own and the question line
   dims itself instead. */
#missionPrompt {
  opacity: 1;
}

.mission-ask {
  display: block;
  opacity: 0.65;
}

.mission-gloss {
  display: block;
  margin-top: 4px;
  font-size: 1.3rem;
  color: var(--ink);
}

.mission-key {
  background: var(--panel-alt);
  border-radius: 10px;
  padding: 8px 14px;
  margin: 0 0 18px;
  font-size: 0.9rem;
}

.mission-key summary {
  cursor: pointer;
  opacity: 0.75;
}

.mission-key p {
  margin: 10px 0 4px;
  line-height: 1.7;
}

/* The four options for a "decode the order" mission are emoji only — showing
   the Swedish word on the button would let him match strings without reading
   the order. */
.mission-emoji-btn {
  font-size: 2.4rem;
  line-height: 1;
  padding: 12px 20px;
}

/* Options are disabled during the feedback pause so a fast second tap can't
   answer the next question by accident. Keep them legible while frozen. */
#missionOptions button:disabled {
  cursor: default;
  opacity: 0.55;
}

.copy-btn {
  font-size: 1.1rem;
  padding: 8px 20px;
  border-radius: 14px;
  border: none;
  background: var(--accent4);
  color: var(--bg);
  cursor: pointer;
  font-family: inherit;
}

code {
  font-family: "Courier New", monospace;
  background: var(--panel-alt);
  border-radius: 6px;
  padding: 2px 6px;
}

.ptable-wrap {
  overflow-x: auto;
  padding-bottom: 6px;
}

.ptable {
  display: grid;
  grid-template-columns: repeat(18, minmax(34px, 1fr));
  grid-template-rows: repeat(7, minmax(34px, 1fr)) 22px repeat(2, minmax(34px, 1fr));
  gap: 3px;
  min-width: 700px;
}

.ptable .elem {
  position: relative;
  border-radius: 6px;
  background: var(--panel-alt);
  border: 2px solid transparent;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2px;
}

.ptable .elem .num {
  position: absolute;
  top: 2px;
  left: 3px;
  font-size: 0.5rem;
  opacity: 0.6;
}

.ptable .elem .sym {
  font-weight: bold;
  font-size: 0.9rem;
}

.ptable .elem .cat-emoji {
  position: absolute;
  bottom: 0;
  right: 1px;
  font-size: 0.5rem;
}

.ptable .elem:hover, .ptable .elem:focus-visible {
  border-color: var(--accent3);
}

.ptable .elem.selected {
  background: var(--accent3);
  border-color: var(--accent4);
}

.ptable .elem.selected .num,
.ptable .elem.selected .sym {
  color: var(--bg);
}

.ptable .elem.placeholder {
  cursor: default;
  opacity: 0.5;
  font-size: 0.65rem;
  text-align: center;
}

.ptable-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  justify-content: center;
  margin-top: 16px;
  font-size: 0.8rem;
  opacity: 0.75;
}

.elem-detail {
  margin-top: 20px;
  min-height: 3rem;
  display: flex;
  align-items: center;
  gap: 18px;
}

.elem-detail-hint {
  margin: 0 auto;
  opacity: 0.7;
  text-align: center;
}

.elem-detail.active {
  background: var(--panel-alt);
  border-radius: 14px;
  padding: 16px 20px;
}

.elem-big {
  font-size: 3rem;
  font-weight: bold;
  flex-shrink: 0;
}

.elem-info h3 {
  margin: 0 0 4px;
}

.elem-info p {
  margin: 0;
}

.elem-info p + p {
  margin-top: 6px;
}

.elem-number {
  opacity: 0.6;
  font-weight: normal;
  font-size: 0.9rem;
}

.bohr-block {
  margin-top: 16px;
}

.bohr-host {
  display: flex;
  justify-content: center;
}

.bohr-svg {
  width: min(220px, 60vw);
  height: auto;
}

.bohr-ring {
  fill: none;
  stroke: var(--muted);
  stroke-width: 1.5;
  opacity: 0.6;
}

.bohr-electron {
  fill: #eaf0ff;
  stroke: #7c8db5;
  stroke-width: 1;
}

.bohr-caption {
  text-align: center;
  opacity: 0.75;
  font-size: 0.85rem;
  margin: 8px 0 0;
}

.mode-panel {
  display: none;
}

.mode-panel.active {
  display: block;
}

.circle-diagram {
  display: flex;
  justify-content: center;
  margin: 16px 0;
}

.circle-diagram-svg {
  width: min(220px, 70vw);
  height: auto;
}

.diagram-label {
  fill: var(--ink);
  font-size: 18px;
  font-weight: bold;
  font-family: inherit;
}

/* Same shape as .circle-diagram/.circle-diagram-svg above, just a generic
   name for shapes.html's square/triangle/pentagon/etc diagrams instead of
   one specific to circles. */
.shape-diagram {
  display: flex;
  justify-content: center;
  margin: 0;
}

.shape-diagram-svg {
  width: min(200px, 65vw);
  height: auto;
}

/* Text beside its diagram (text on the left, shape on the right) instead
   of stacked above/below — wraps to stacked automatically on narrow
   screens since there's no room for two columns. */
.shape-row {
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
  margin-top: 12px;
}

.shape-row .shape-text {
  flex: 1 1 220px;
}

.shape-row .shape-diagram {
  flex: 0 0 auto;
  margin: 0 auto;
}

.clock-host {
  display: flex;
  justify-content: center;
  margin: 16px 0;
}

.clock-svg {
  width: min(300px, 80vw);
  height: auto;
}

.clock-face {
  fill: var(--panel-alt);
  stroke: var(--accent4);
  stroke-width: 3;
}

.clock-tick {
  stroke: var(--muted);
  stroke-width: 2;
}

.clock-number {
  fill: var(--ink);
  font-size: 16px;
  font-weight: bold;
  font-family: inherit;
  text-anchor: middle;
  dominant-baseline: central;
  pointer-events: none;
}

.clock-hand {
  stroke: var(--ink);
  stroke-linecap: round;
}

.clock-hand-hour {
  stroke-width: 6;
}

.clock-hand-minute {
  stroke-width: 4;
}

.clock-center {
  fill: var(--accent4);
}

.clock-hit {
  fill: transparent;
  cursor: pointer;
}

.clock-hit:hover, .clock-hit:focus-visible {
  fill: rgba(255, 255, 255, 0.08);
}

.clock-hit.picked {
  fill: rgba(255, 255, 255, 0.18);
}

.clock-hint {
  text-align: center;
  opacity: 0.7;
  font-size: 0.9rem;
  margin: 0 0 14px;
}

.clock-swedish {
  text-align: center;
  font-style: italic;
  opacity: 0.8;
  margin: 4px 0 0;
}

.time-picker {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.time-picker select, .time-picker input {
  font-size: 1.3rem;
  padding: 8px 10px;
  border-radius: 12px;
  border: 3px solid var(--accent2);
  background: var(--panel-alt);
  color: var(--ink);
  font-family: inherit;
}

.time-picker input {
  width: 160px;
  max-width: 100%;
  text-align: center;
}

/* Pi Quiz second-chance lock: input still focused (so the on-screen
   keyboard stays up), just ignoring keystrokes for a moment. */
.time-picker input.locked {
  border-color: var(--bad);
  opacity: 0.6;
}

.time-colon {
  font-size: 1.3rem;
  font-weight: bold;
}

.time-picker button {
  font-size: 1.2rem;
  padding: 10px 22px;
  border-radius: 14px;
  border: none;
  background: var(--accent4);
  color: var(--bg);
  cursor: pointer;
  font-family: inherit;
}

.pie-host {
  display: flex;
  justify-content: center;
  margin: 16px 0;
}

.pie-svg {
  width: min(300px, 80vw);
  height: auto;
}

/* Unfilled slices are the grey --panel-alt. This was briefly --bg, to stop
   the grey wedges competing with the white filled ones for "the shaded
   one" — but the fix that actually landed was renaming the page's wording
   from "shaded" to "filled" (see PROJECT-NOTES.md), so the grey is back by
   request. Must stay an OPAQUE fill, not fill:none, whatever the colour —
   clicks inside an empty slice have to hit-test in "Show the Fraction". */
.pie-slice {
  fill: var(--panel-alt);
  stroke: var(--border);
  stroke-width: 2;
}

.pie-slice.filled {
  fill: var(--accent4);
}

.pie-slice.interactive {
  cursor: pointer;
}

.pie-slice.interactive:hover {
  opacity: 0.85;
}

.sudoku-grid {
  display: grid;
  gap: 4px;
  max-width: 320px;
  margin: 20px auto;
  padding: 4px;
  background: var(--border);
  border-radius: 12px;
}

/* 9x9 has more than twice the cells of 4x4 in the same rough footprint,
   so it gets its own (larger) max-width and (smaller) per-cell font —
   otherwise cells shrink below a comfortable tap target on a tablet. */
.sudoku-grid.size-9 {
  max-width: 500px;
}

.sudoku-cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  font-weight: bold;
  border-radius: 8px;
  background: var(--panel-alt);
  color: var(--ink);
  cursor: pointer;
  border: 2px solid transparent;
}

.sudoku-grid.size-9 .sudoku-cell {
  font-size: 1.3rem;
  border-radius: 6px;
}

.sudoku-cell.given {
  color: var(--muted);
  cursor: default;
}

.sudoku-cell.selected {
  border-color: var(--accent4);
}

.sudoku-cell.wrong {
  color: var(--bad);
}

.ttt-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  max-width: 320px;
  margin: 16px auto 20px;
}

.ttt-cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.6rem;
  border-radius: 14px;
  background: var(--panel-alt);
  cursor: pointer;
  border: 3px solid transparent;
}

.ttt-cell.selected {
  border-color: var(--accent4);
}

.ttt-grid.over .ttt-cell {
  cursor: default;
}

/* 2048's tile-color ramp is a second deliberate exception to the site's
   monochrome rule (see TILE_COLORS in 2048.js and PROJECT-NOTES.md) — the
   colors are set inline per-tile in JS, this just lays out the board. */
.board2048-wrap {
  /* Board + D-pad side by side; on narrow phones the D-pad wraps to
     below the board instead of squeezing it. */
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin: 16px 0 20px;
}

.grid2048 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  width: min(340px, 100%);
  padding: 8px;
  background: var(--panel-alt);
  border-radius: 12px;
  touch-action: none;
  cursor: pointer;
}

.dpad2048 {
  display: grid;
  grid-template-areas:
    '.    up    .'
    'left .     right'
    '.    down  .';
  gap: 6px;
}

.dpad2048 button {
  width: 54px;
  height: 54px;
  border: none;
  border-radius: 12px;
  background: var(--panel-alt);
  color: var(--ink);
  font-size: 1.3rem;
  font-family: inherit;
  cursor: pointer;
}

.dpad2048 button:active {
  background: #303036;
}

.dpad2048 .dpad-up { grid-area: up; }
.dpad2048 .dpad-left { grid-area: left; }
.dpad2048 .dpad-right { grid-area: right; }
.dpad2048 .dpad-down { grid-area: down; }

.tile2048 {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  font-weight: bold;
  border-radius: 8px;
  background: var(--border);
}

.memory-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  max-width: 400px;
  margin: 20px auto;
}

.memory-card {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  font-weight: bold;
  border-radius: 10px;
  background: var(--panel-alt);
  color: var(--ink);
  cursor: pointer;
  border: 2px solid transparent;
}

.memory-card.flipped {
  background: var(--accent4);
  color: var(--bg);
}

.memory-card.matched {
  /* background/color set inline per-pair in memory.js (pairColor()) */
  cursor: default;
  opacity: 0.85;
}

/* Nordic countries: the one deliberate exception to the site's monochrome
   rule — the flags ARE color (that's the whole teaching point, they're
   almost impossible to tell apart in greyscale), see PROJECT-NOTES.md. */
.flag-grid {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 20px;
}

.flag-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  background: var(--panel-alt);
  border: 3px solid transparent;
  border-radius: 14px;
  padding: 10px 14px;
  cursor: pointer;
  font-family: inherit;
  color: var(--ink);
}

.flag-card:hover, .flag-card:focus-visible {
  border-color: var(--accent3);
}

.flag-card.active {
  border-color: var(--accent4);
}

.flag-card.static {
  cursor: default;
}

.flag-card span {
  font-weight: bold;
  font-size: 0.9rem;
}

.flag-svg {
  width: 70px;
  height: auto;
  border-radius: 4px;
  display: block;
}

.flag-svg.large {
  width: 120px;
  flex-shrink: 0;
}

.bit-row {
  display: flex;
  gap: 6px;
  justify-content: center;
  flex-wrap: wrap;
  margin: 16px 0;
}

.bit {
  width: 44px;
  height: 60px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  border-radius: 10px;
  border: 3px solid transparent;
  background: var(--panel-alt);
  color: var(--ink);
  font-family: inherit;
  cursor: pointer;
}

.bit:disabled {
  cursor: default;
}

/* Gap before the 5th bit splits the byte into its two nibbles — one hex
   digit each, see the Binary & Hex facts panel. */
.bit.nibble-start {
  margin-left: 14px;
}

.bit .place-value {
  font-size: 0.65rem;
  opacity: 0.6;
}

.bit .bit-value {
  font-size: 1.4rem;
  font-weight: bold;
}

.bit.on {
  background: var(--accent4);
  border-color: var(--accent4);
  color: var(--bg);
}

/* what-beats-a.html: the current letter is the entire question — the page says
   nothing else — so it's the biggest thing on the screen, and per Elton it is
   the ONLY thing above the textbox. Monospace so the letters read as a code
   rather than a word; word-break so a long term wraps inside the panel instead
   of bleeding past both screen edges (a centred flex item that overflows is
   partly unreachable — see the horizontal-scroll note in PROJECT-NOTES.md). */
.beats-current {
  font-family: "Courier New", monospace;
  /* Deliberately huge — the letter IS the page. Capped in rem so it can't
     dwarf a desktop panel, and in vw so it can't outgrow a phone. */
  font-size: min(8rem, 26vw);
  font-weight: bold;
  line-height: 1.1;
  /* The board starts EMPTY (Elton, 2026-08-19) — the first letter he types is
     A. An empty <p> collapses to nothing, which would slide the textbox up
     the page and drop it back down on the first answer, so keep the line's
     height reserved whether or not there's a letter in it. */
  min-height: 1.1em;
  letter-spacing: 4px;
  margin: 10px 0 26px;
  text-align: center;
  word-break: break-all;
}

/* The input row's own centre line has to land under the letter, and the Go
   button would otherwise shove the textbox half a button's width to the left.
   An empty gutter of equal flex on the other side cancels it out. Deleting
   those empty spans as "pointless markup" silently un-centres the page. */
.beats-row {
  flex-wrap: nowrap;
}

/* .time-picker sets display: flex, which beats the [hidden] attribute's UA
   display: none — without this the NEXT button and the textbox are both on
   screen at once. */
.time-picker[hidden] {
  display: none;
}

.beats-gutter {
  flex: 1 1 0;
  min-width: 0;
}

.beats-row .beats-go {
  text-align: left;
}

/* The run's history, newest first: "Z 😵 E 👊 D 👊 C 👊 B 👊 A". Muted and
   small — the giant letter above is the thing being answered; this is the
   story of how it got there, including (after a loss) the guess that died. */
.beats-chain {
  font-family: "Courier New", monospace;
  font-size: 1.15rem;
  line-height: 1.9;
  letter-spacing: 1px;
  color: var(--muted);
  text-align: center;
  margin: 22px 0 0;
  min-height: 2rem;
  word-break: break-word;
}

/* The Pi Quiz head start ("Start from 100"). Quiet on purpose, the same way
   what-beats-a's SKIP is: it isn't part of playing, it's a shortcut past the
   digits she already knows cold, and it only appears at the start of a run on
   a device whose best is past 100. */
.pi-head-start-row {
  margin-top: 12px;
}

.pi-head-start-row button {
  font-size: 1rem;
  padding: 6px 16px;
  background: var(--panel-alt);
  color: var(--muted);
  border: 2px solid var(--accent2);
}

/* The "skip the free stretch" button. Deliberately quieter than Go and NEXT —
   it isn't part of playing, it's a shortcut past the part that plays itself,
   and the opening screen is meant to stay bare. */
.beats-skip-row {
  margin-top: 14px;
}

.beats-skip-row button {
  font-size: 1rem;
  padding: 6px 16px;
  background: var(--panel-alt);
  color: var(--muted);
  border: 2px solid var(--accent2);
  font-family: "Courier New", monospace;
  letter-spacing: 1px;
}

/* Asked for only on the lost-run screen, and only when practice.html hasn't
   already cached a name — so the board can have a name on it without putting
   a gate in front of Elton's deliberately bare opening screen. Borrows the
   name-gate chrome above rather than inventing a second look for one field. */
.beats-name {
  margin-top: 16px;
  text-align: center;
}

/* Coin purse badge (coins.js) — pinned to the top-right corner of every
   page. Chrome borrowed from `nav a` so it reads as part of the site
   furniture; the 🪙 emoji is the only color, no new palette entries (see
   the monochrome note in PROJECT-NOTES.md). */
.coin-badge {
  position: fixed;
  top: 10px;
  right: 10px;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-radius: 999px;
  background: var(--panel);
  border: 1px solid var(--border);
  box-shadow: 0 4px 0 rgba(0,0,0,0.4);
  font-size: 1.1rem;
  line-height: 1;
  /* The badge sits over the page, so a stray tap/drag on it shouldn't
     select the number or block a tap meant for what's underneath. */
  user-select: none;
  pointer-events: none;
}

.coin-badge b {
  font-size: 1.3rem;
}

.coin-badge-label {
  font-size: 1rem;
  color: var(--muted);
}

/* Pulse when a coin lands — the "+1" alone is small and easy to miss with
   your eyes on the middle of the screen. */
.coin-badge.bumped {
  animation: coin-bump 0.6s ease;
}

@keyframes coin-bump {
  0%   { transform: scale(1); }
  35%  { transform: scale(1.18); }
  100% { transform: scale(1); }
}

.coin-gain {
  position: absolute;
  top: 100%;
  right: 14px;
  font-weight: bold;
  color: var(--good);
  animation: coin-gain-float 1.1s ease-out forwards;
}

@keyframes coin-gain-float {
  0%   { opacity: 0; transform: translateY(-6px); }
  25%  { opacity: 1; transform: translateY(0); }
  100% { opacity: 0; transform: translateY(14px); }
}

/* The badge is fixed, so it doesn't reserve space in the flow, and the
   header's <h1> is centred and full-bleed — nothing keeps the title out of
   the top-right corner on its own. Two defences, split at the same 900px
   the rest of the sheet uses:

   Below that, the title is close to the full width of the screen whatever
   it says, so no amount of horizontal room helps — give the badge its own
   row above everything instead.

   Above it, reserve the badge's width plus its 10px inset on BOTH sides
   so the title stays centred and simply wraps a line earlier rather than
   running underneath. A max-width media query was the first attempt and it
   was wrong: the title is capped at 3.2rem but the badge keeps sliding
   right with the viewport, so each long title has its own overlap band
   (big-numbers ~901-925px, elton ~1100-1184px — iPad landscape sits in
   that second one). Any fixed breakpoint just moves the band to wherever
   the next long title happens to land.

   The reservation must be >= the badge, not merely close to it: the ink is
   bounded by the padded content box, so equality is what makes an overlap
   impossible at every width at once. That used to be a hand-measured 180px
   (the badge is 168.5px at "moneys: 9999" — the word made it more than twice
   the 82px the coin symbol needed), with the standing warning that a
   five-digit purse would need it raised and nothing enforcing that. Since a
   coin now lands on every correct answer, five digits is a matter of weeks,
   so coins.js measures the badge and publishes `--coin-reserve` (its real
   width + the 10px inset) on every render and on any resize. The 180px below
   is the fallback for the moment before the first measurement — and for the
   four-digit purse it was always sized to. */
@media (max-width: 900px) {
  body {
    padding-top: 62px;
  }
}

/* weekday.html — the date being asked about. Same job as .problem .expr,
   but a spelled-out date ("17 September 1987") is roughly three times the
   characters of an arithmetic expression, so that clamp's 10vw overflows a
   phone. */
.weekday-date {
  font-size: clamp(1.5rem, 6vw, 2.4rem);
  font-weight: bold;
  text-align: center;
  margin: 6px 0 18px;
}

/* A date input renders its own MM/DD/YYYY (or locale equivalent) spinner,
   which .time-picker's 160px clips at the last digit of the year. */
.time-picker input[type="date"] {
  width: auto;
  min-width: 200px;
}

.weekday-answer {
  text-align: center;
  font-size: 1.3rem;
  font-weight: bold;
  margin: 14px 0 18px;
}

/* Seven weekday buttons have to fit a phone without one falling to a second
   row on its own, so they're smaller than the .op-picker default. */
.weekday-options button {
  font-size: 1.1rem;
  padding: 8px 12px;
}

/* Step labels take only the width they need, so the working beside them
   gets the rest. On a phone they also have to wrap: .steps-table's nowrap
   would hand "4. Doomsday dates that month" half a 320px screen and squeeze
   the working into a tall sliver. There's room for one line each as soon as
   the screen isn't a phone. */
.weekday-steps td:first-child {
  width: 1%;
  white-space: normal;
}

@media (min-width: 561px) {
  .weekday-steps td:first-child {
    white-space: nowrap;
  }
}

/* The anchors and doomsday dates, collapsed by default: the point of the
   page is recalling them, but a beginner shouldn't have to switch tabs. */
.cheat-sheet {
  margin-top: 20px;
  background: var(--panel-alt);
  border-radius: 12px;
  padding: 10px 14px;
}

.cheat-sheet summary {
  cursor: pointer;
  font-weight: bold;
}

.cheat-sheet p {
  font-size: 0.95rem;
  opacity: 0.85;
}

@media (min-width: 901px) {
  header h1 {
    padding-inline: var(--coin-reserve, 180px);
  }
}