:root {
  --bg: #f4efe4;
  --paper: #fffdf8;
  --ink: #1d2742;
  --muted: #6b7280;
  --grid: #d3e4f4;
  --accent: #ff7a2f;
  --accent-soft: #ffe7d6;
  --teal: #0f8f7e;
  --teal-soft: #d9f3ee;
  --red: #c9382e;
  --red-soft: #fde5e2;
  --blue: #2f6fd6;
  --blue-soft: #e3edfc;
  --gold: #f5b400;
  --hl: #fff1a1;
  --cell: 54px;
  --radius: 18px;
  --shadow: 0 1px 0 rgba(29, 39, 66, .06), 0 8px 24px rgba(29, 39, 66, .08);
  font-family: ui-rounded, "SF Pro Rounded", "Nunito", "Segoe UI", system-ui, sans-serif;
  color: var(--ink);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

#app { max-width: 1040px; margin: 0 auto; padding: 24px 20px 60px; }

h1, h2 { margin: 0; letter-spacing: -0.01em; }
.muted { color: var(--muted); }
.eyebrow {
  display: block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 4px;
}

kbd {
  font: inherit;
  font-size: .85em;
  font-weight: 700;
  padding: 1px 7px;
  border-radius: 6px;
  background: var(--paper);
  border: 1px solid #d8d2c4;
  border-bottom-width: 3px;
}

/* ---------- buttons ---------- */
.btn {
  font: inherit;
  font-weight: 700;
  font-size: 16px;
  color: var(--ink);
  background: var(--paper);
  border: 2px solid #e2dccd;
  border-radius: 12px;
  padding: 10px 18px;
  cursor: pointer;
  transition: transform .12s ease, background .12s ease, border-color .12s ease;
}
.btn:hover:not(:disabled) { transform: translateY(-1px); border-color: #cfc7b4; }
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:disabled { opacity: .4; cursor: default; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover:not(:disabled) { background: #f56b1d; border-color: #f56b1d; }
.btn.ghost { background: transparent; border-color: transparent; }
.btn.ghost:hover:not(:disabled) { border-color: #e2dccd; }
.btn.soft { background: var(--blue-soft); border-color: var(--blue-soft); color: var(--blue); }
.btn.small { font-size: 14px; padding: 6px 12px; border-radius: 10px; }

/* ---------- level map ---------- */
.hero { text-align: center; margin: 8px 0 32px; }
.hero-mascot { display: block; width: 150px; height: auto; margin: 0 auto 10px; animation: hop .7s cubic-bezier(.3, 1.5, .5, 1) both; }
.hero h1 { font-size: clamp(40px, 7vw, 64px); font-weight: 800; }
.hero-sub { color: var(--muted); font-size: 18px; margin: 8px 0 0; }

.levels {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
}
.level-card {
  font: inherit;
  color: inherit;
  text-align: left;
  display: grid;
  gap: 6px;
  padding: 18px;
  background: var(--paper);
  border: 2px solid transparent;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform .15s ease, border-color .15s ease;
}
.level-card:hover:not(:disabled) { transform: translateY(-3px); border-color: var(--accent); }
.level-card.locked { opacity: .55; cursor: default; box-shadow: none; }
.level-num {
  width: 40px; height: 40px;
  display: grid; place-items: center;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 800;
  font-size: 18px;
}
.level-card.locked .level-num { background: #ece7db; }
.level-name { font-size: 20px; font-weight: 800; }
.level-blurb { color: var(--muted); font-size: 15px; line-height: 1.35; }
.level-status { font-weight: 700; font-size: 15px; color: var(--muted); margin-top: 4px; }
.level-card.played .level-status { color: #b58500; }

.grownups {
  margin-top: 40px;
  background: var(--paper);
  border-radius: var(--radius);
  padding: 16px 20px;
  box-shadow: var(--shadow);
}
.grownups summary { cursor: pointer; font-weight: 700; }
.bars { list-style: none; padding: 0; margin: 16px 0; display: grid; gap: 10px; }
.bars li { display: grid; grid-template-columns: minmax(180px, 320px) 1fr 40px; gap: 12px; align-items: center; font-size: 15px; }
.bar { height: 12px; border-radius: 6px; background: #efeadf; overflow: hidden; }
.bar span { display: block; height: 100%; background: var(--accent); border-radius: 6px; }
.bar-val { font-weight: 700; text-align: right; font-variant-numeric: tabular-nums; }

/* ---------- play screen ---------- */
.topbar {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}
.topbar-title { font-size: 22px; font-weight: 800; }
.topbar-meta { display: flex; gap: 14px; align-items: center; color: var(--muted); font-weight: 700; }
.star-count { color: #b58500; background: #fff3c4; padding: 4px 10px; border-radius: 999px; }

.tracker-wrap { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 16px; margin-bottom: 14px; }
.tracker { display: flex; flex-wrap: wrap; gap: 6px; list-style: none; padding: 0; margin: 0; }
.tracker li {
  padding: 6px 14px;
  border-radius: 999px;
  background: #ebe5d8;
  color: var(--muted);
  font-weight: 700;
  font-size: 15px;
  transition: background .2s ease, color .2s ease, transform .2s ease;
}
.tracker li.pre { background: transparent; border: 2px dashed #d8d1c1; padding: 4px 12px; }
.tracker li.on { background: var(--accent); color: #fff; border-color: var(--accent); transform: scale(1.06); }
.mnemonic { margin: 0; color: var(--muted); font-size: 14px; }
.mnemonic b { color: var(--accent); }

.prompt {
  background: var(--paper);
  border-radius: var(--radius);
  padding: 16px 20px;
  font-size: 19px;
  line-height: 1.45;
  box-shadow: var(--shadow);
}
.hl-text { background: var(--hl); padding: 0 4px; border-radius: 4px; font-weight: 700; }

.feedback {
  min-height: 48px;
  margin: 10px 0 14px;
  padding: 12px 18px;
  border-radius: 14px;
  font-size: 17px;
  line-height: 1.4;
  font-weight: 600;
}
.feedback.empty { background: transparent; }
.feedback.good { background: var(--teal-soft); color: var(--teal); }
.feedback.oops { background: var(--red-soft); color: var(--red); animation: shake .35s ease; }
.feedback.reveal { background: var(--blue-soft); color: var(--blue); }
.feedback.info { background: #fff3c4; color: #8a6500; }

.workspace { display: grid; grid-template-columns: 1fr 230px; gap: 16px; align-items: start; }

.board-card {
  background: var(--paper);
  border-radius: var(--radius);
  padding: 20px 24px 18px;
  box-shadow: var(--shadow);
  overflow-x: auto;
}
.problem-label { color: var(--muted); font-weight: 700; font-size: 14px; margin-bottom: 10px; }

/* ---------- the graph-paper board ---------- */
.board {
  display: grid;
  grid-template-columns: minmax(var(--cell), auto) repeat(var(--n), var(--cell));
  grid-auto-rows: var(--cell);
  width: max-content;
  margin: 0 auto;
  font-size: calc(var(--cell) * .62);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  position: relative;
}
.cell, .gutter {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}
.cell { box-shadow: inset -1px -1px 0 var(--grid); }
.cell.q { color: var(--accent); }
.gutter { justify-content: flex-end; padding-right: 14px; }
.gutter.divisor { color: var(--ink); }
.gutter.minus, .cell.minus { color: var(--muted); }

.bracket {
  pointer-events: none;
  border-top: 4px solid var(--ink);
  border-left: 4px solid var(--ink);
  border-top-left-radius: 22px 100%;
  margin-left: -6px;
  z-index: 1;
}

.dot {
  position: absolute;
  right: -6px;
  bottom: 9px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: currentColor;
  z-index: 2;
}
.dot-target {
  position: absolute;
  right: -12px;
  bottom: 3px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  border: 2px dashed var(--blue);
  background: var(--paper);
  cursor: pointer;
  z-index: 3;
  padding: 0;
  animation: ring 1.6s ease-in-out infinite;
}
.dot-target:hover { background: var(--blue); border-style: solid; }

.cell.pickable { cursor: pointer; }
.cell.pickable:hover { background: var(--accent-soft); }
.cell.cursor { background: var(--accent-soft); box-shadow: inset 0 0 0 3px var(--accent); border-radius: 6px; }
.cell.cursor:empty::after {
  content: "";
  width: 3px;
  height: 55%;
  background: var(--accent);
  animation: blink 1s steps(1) infinite;
}

.cell.hl { background: var(--hl); }
.cell.line { box-shadow: inset 0 -3px 0 var(--ink), inset -1px 0 0 var(--grid); }
.cell.live { background: var(--accent-soft); }
.cell.live.line { box-shadow: inset 0 -3px 0 var(--ink), inset 0 0 0 2px var(--accent); }
.cell.live:not(.line) { box-shadow: inset 0 0 0 2px var(--accent); }

.cell.dd.used { color: #9aa3b5; }
.cell.dd.used::after { content: "\2193"; position: absolute; bottom: -2px; right: 4px; font-size: 13px; color: var(--accent); }
.cell.bringable { cursor: pointer; }
.cell.bringable:hover { background: var(--accent-soft); border-radius: 6px; transform: translateY(-2px); }
.cell.glow { background: var(--accent-soft); border-radius: 6px; animation: glow 1.2s ease-in-out infinite; }

.cell.pop { animation: pop .35s cubic-bezier(.3, 1.6, .5, 1); }
.cell.drop { animation: drop .45s cubic-bezier(.3, 1.3, .5, 1); color: var(--accent); }

.entry-hint {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 15px;
}

/* ---------- step 0: hop the decimal ---------- */
.shift-stage { text-align: center; padding: 10px 0 4px; }
.shift-problem {
  display: inline-flex;
  align-items: flex-end;
  gap: 18px;
  font-size: 48px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  margin: 10px 0 16px;
}
.shift-dividend {
  border-top: 4px solid var(--ink);
  border-left: 4px solid var(--ink);
  border-top-left-radius: 22px 100%;
  padding: 4px 14px 0 18px;
}
.sd { display: inline-block; min-width: .62em; }
.sd.added { color: var(--accent); animation: pop .35s ease; }
.sdot {
  display: inline-block;
  width: 11px;
  height: 11px;
  margin: 0 4px;
  border-radius: 50%;
  background: var(--blue);
  font-size: 0;
  vertical-align: baseline;
  animation: pop .3s ease;
}
.sdot.end { opacity: .35; }
.shift-note { color: var(--muted); font-size: 16px; margin: 0 0 16px; }
.shift-controls { display: flex; justify-content: center; gap: 10px; flex-wrap: wrap; }

/* ---------- helper ---------- */
.helper {
  background: var(--paper);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
}
.helper .btn { width: 100%; }
.helper-note { color: var(--muted); font-size: 14px; line-height: 1.4; margin: 12px 0 0; }
.multiples { list-style: none; padding: 0; margin: 12px 0 0; display: grid; gap: 4px; font-variant-numeric: tabular-nums; }
.multiples li { display: flex; justify-content: space-between; padding: 6px 10px; border-radius: 8px; background: var(--blue-soft); font-size: 17px; }
.multiples b { color: var(--blue); }

/* ---------- done states ---------- */
.done-panel {
  display: grid;
  grid-template-columns: auto auto 1fr auto;
  align-items: center;
  gap: 20px;
  background: var(--paper);
  border: 3px solid var(--teal);
  border-radius: var(--radius);
  padding: 16px 22px;
  box-shadow: var(--shadow);
  animation: rise .4s ease;
}
.done-panel h2 { font-size: 22px; }
.done-panel p { margin: 4px 0 0; }
.check { color: var(--teal); font-weight: 700; }

.star { color: #e3ddcf; font-size: 34px; display: inline-block; }
.star.on { color: var(--gold); animation: pop .5s cubic-bezier(.3, 1.6, .5, 1) both; }
.star.on:nth-child(2) { animation-delay: .12s; }
.star.on:nth-child(3) { animation-delay: .24s; }

.level-done { text-align: center; padding: 24px 0 40px; }
.level-done-mascot { display: block; width: 190px; height: auto; margin: 0 auto 12px; animation: cheer .9s ease .1s both; }
.done-mascot { width: 76px; height: auto; animation: cheer .8s ease both; }
.level-done h1 { font-size: 48px; margin-bottom: 24px; }
.level-done-stars { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px 22px; }
.mini-stars .star { font-size: 28px; }
.total { font-size: 28px; font-weight: 800; color: #b58500; margin: 20px 0 8px; }
.trophy { font-size: 22px; font-weight: 700; }
.actions { display: flex; justify-content: center; gap: 12px; flex-wrap: wrap; margin-top: 24px; }

/* ---------- motion ---------- */
@keyframes pop { 0% { transform: scale(.4); opacity: 0; } 100% { transform: scale(1); opacity: 1; } }
@keyframes drop { 0% { transform: translateY(-160%); opacity: 0; } 100% { transform: translateY(0); opacity: 1; } }
@keyframes hop { 0% { transform: translateY(24px) scale(.85); opacity: 0; } 100% { transform: none; opacity: 1; } }
@keyframes cheer {
  0% { transform: translateY(12px) scale(.8); opacity: 0; }
  35% { transform: translateY(-14px) rotate(-7deg); opacity: 1; }
  65% { transform: translateY(0) rotate(5deg); }
  100% { transform: none; }
}
@keyframes rise { 0% { transform: translateY(8px); opacity: 0; } 100% { transform: none; opacity: 1; } }
@keyframes shake { 0%, 100% { transform: none; } 25% { transform: translateX(-6px); } 75% { transform: translateX(6px); } }
@keyframes blink { 50% { opacity: 0; } }
@keyframes glow { 0%, 100% { box-shadow: inset 0 0 0 2px var(--accent); } 50% { box-shadow: inset 0 0 0 4px var(--accent); } }
@keyframes ring { 0%, 100% { box-shadow: 0 0 0 0 rgba(47, 111, 214, .35); } 50% { box-shadow: 0 0 0 6px rgba(47, 111, 214, 0); } }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}

@media (max-width: 760px) {
  :root { --cell: 44px; }
  .workspace { grid-template-columns: 1fr; }
  .topbar { grid-template-columns: auto 1fr; }
  .topbar-meta { grid-column: 1 / -1; }
  .done-panel { grid-template-columns: 1fr; text-align: center; justify-items: center; }
  .bars li { grid-template-columns: 1fr 60px 32px; }
}