/* A classroom periodic table: cool grey paper, white tiles with ink borders,
   a big symbol in each tile, mono numerals, and filled tiles in the pastel
   family colours of a wall chart. */
:root {
  color-scheme: light;
  --page: #e9ecef;
  --surface: #ffffff;
  --ink: #1b1f24;
  --faded: #6b7280;
  --rule: #c8cdd3;
  --accent: #0b6e99;
  --number: #1b1f24;
  --wrong: #b3261e;
  --alkali: #f8b4b4;
  --alkaline: #fbd59c;
  --transition: #fbe7a1;
  --post: #cfe8c8;
  --metalloid: #b9e0d2;
  --nonmetal: #b7d8f2;
  --noble: #d4c5f0;
  --lanthanide: #f2c6e0;
  --actinide: #e3c3b0;
  --unknown: #e3e6ea;
  --text: "IBM Plex Sans", "Helvetica Neue", Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
}

[hidden] { display: none !important; }
* { box-sizing: border-box; }
html, body { max-width: 100%; overflow-x: hidden; }

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font: 16px/1.45 var(--text);
}

main {
  max-width: 600px;
  margin: 20px auto;
  padding: 26px;
  background: var(--surface);
  border: 2px solid var(--ink);
}

main > header {
  position: relative;
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
}
.logo {
  flex: none;
  position: relative;
  width: 40px;
  height: 40px;
  border: 2px solid var(--ink);
  background: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  font: 700 1.1rem/1 var(--text);
}
.logo i { position: absolute; top: 2px; left: 4px; font: 400 0.55rem/1 var(--mono); }
.logo b { font-weight: 700; }
h1 { font: 700 1.6rem/1 var(--text); letter-spacing: -0.02em; margin: 0; margin-right: auto; }
.status { display: flex; gap: 14px; white-space: nowrap; font: 0.85rem var(--mono); color: var(--faded); }
#score { color: var(--accent); font-weight: 600; }

.icon { display: flex; padding: 4px; color: var(--faded); background: none; border: 0; cursor: pointer; }
.icon:hover { color: var(--accent); }

.days { display: flex; align-items: center; gap: 10px; margin-bottom: 14px; font: 0.9rem var(--mono); }
.days button { font: inherit; font-size: 1.3rem; font-weight: 600; line-height: 1; color: var(--accent); background: none; border: 0; padding: 4px 12px; min-width: 44px; cursor: pointer; }
.days button:disabled { color: var(--faded); opacity: 0.45; cursor: default; }
#day { min-width: 10em; text-align: center; }
.days .today { margin-left: auto; font-size: 0.85rem; border-bottom: 1px solid currentColor; padding: 0; min-width: 0; }

.board {
  display: grid;
  grid-template-columns: minmax(64px, 0.8fr) repeat(3, minmax(0, 1fr));
  gap: 5px;
}
.label {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  text-align: center;
  font-size: 0.72rem;
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  padding: 6px 4px;
  min-width: 0;
  overflow-wrap: anywhere;
  hyphens: auto;
}
.board > .label:nth-child(-n+4) { justify-content: flex-end; }
.ref { font: 0.68rem var(--mono); color: var(--faded); letter-spacing: 0.1em; }

/* A tile: number top left, symbol large, name and rarity below, like a wall chart. */
.cell {
  position: relative;
  aspect-ratio: 1;
  min-width: 0;
  background: var(--surface);
  border: 1.5px dashed var(--rule);
  border-radius: 0;
  color: inherit;
  font: inherit;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1px;
  padding: 14px 4px 6px;
  text-align: center;
  cursor: pointer;
  overflow: hidden;
}
.cell:hover { border-color: var(--faded); }
.cell.selected { border: 2px solid var(--accent); background: color-mix(in srgb, var(--accent) 8%, var(--surface)); }
.cell.filled { border: 1.5px solid var(--ink); cursor: default; }
.cell.over { cursor: pointer; }
.cell.filled.selected { box-shadow: inset 0 0 0 2px var(--accent); }
.cell .ref { position: absolute; top: 5px; left: 7px; visibility: hidden; }
.cell.selected .ref { visibility: visible; color: var(--accent); }
.cell .number { position: absolute; top: 4px; left: 6px; font: 0.7rem var(--mono); }
.cell .symbol { font: 700 1.9rem/1 var(--text); letter-spacing: -0.02em; }
.cell .name { font-size: 0.72rem; line-height: 1.15; max-width: 100%; overflow-wrap: anywhere; }
.cell .mass { font: 0.68rem var(--mono); color: var(--faded); }
.family-alkali { background: var(--alkali); }
.family-alkaline { background: var(--alkaline); }
.family-transition { background: var(--transition); }
.family-post { background: var(--post); }
.family-metalloid { background: var(--metalloid); }
.family-nonmetal { background: var(--nonmetal); }
.family-noble { background: var(--noble); }
.family-lanthanide { background: var(--lanthanide); }
.family-actinide { background: var(--actinide); }
.family-unknown { background: var(--unknown); }
.cell.shake { animation: shake 0.3s; border-color: var(--wrong); }
@keyframes shake {
  25% { transform: translateX(-4px); }
  75% { transform: translateX(4px); }
}
@media (prefers-reduced-motion: reduce) {
  .cell.shake { animation: none; }
}


/* The pick-from table: 18 columns, main body on rows 1–7, the f-block two rows further down. */
.table-wrap { margin-top: 16px; overflow-x: auto; }
.table { display: grid; grid-template-columns: repeat(18, minmax(24px, 1fr)); grid-auto-rows: 24px; gap: 2px; min-width: 466px; }
.tile {
  padding: 0;
  font: 600 0.62rem/1 var(--mono);
  color: var(--ink);
  border: 1px solid var(--ink);
  border-radius: 0;
  cursor: pointer;
}
.tile:hover:not(:disabled) { outline: 2px solid var(--accent); outline-offset: -1px; }
.tile.used { background: var(--rule); color: var(--faded); text-decoration: line-through; }
.tile:disabled { cursor: default; }
.tile:disabled:not(.used) { opacity: 0.6; }

.entry { position: relative; margin-top: 16px; }
.entry input {
  width: 100%;
  padding: 9px 10px;
  font: inherit;
  color: inherit;
  background: var(--surface);
  border: 1.5px solid var(--ink);
  border-radius: 0;
  caret-color: var(--accent);
}
.entry input::placeholder { color: var(--faded); }
.entry input:focus { outline: none; border-color: var(--accent); box-shadow: inset 0 0 0 1px var(--accent); }
.suggestions {
  list-style: none;
  margin: 0;
  padding: 0;
  position: absolute;
  left: 0;
  right: 0;
  z-index: 1;
  background: var(--surface);
  border: 1.5px solid var(--ink);
  border-top: 0;
}
.suggestions:empty { display: none; }
.suggestions li { padding: 8px 10px; cursor: pointer; color: var(--accent); font-weight: 600; }
.suggestions li::after { content: "  ⏎"; white-space: pre; color: var(--faded); font-weight: 400; }

.message { white-space: pre-line; overflow-wrap: anywhere; min-height: 1.45em; margin: 10px 0 0; font-size: 0.9rem; color: var(--faded); }
.message.wrong { color: var(--wrong); }

.actions { display: flex; gap: 10px; margin-top: 10px; }
.actions button {
  font: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--ink);
  background: var(--surface);
  border: 1.5px solid var(--ink);
  border-radius: 0;
  padding: 6px 12px;
  cursor: pointer;
}
.actions button:hover { color: var(--accent); border-color: var(--accent); }
button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.answers { margin-top: 22px; }
.answers h2 { font-size: 0.8rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.04em; margin: 0 0 6px; padding-bottom: 6px; border-bottom: 1.5px solid var(--ink); }
.answers ol { list-style: none; margin: 0; padding: 0; }
.answers li { display: flex; justify-content: space-between; gap: 12px; padding: 4px 0; font-size: 0.9rem; border-bottom: 1px solid var(--rule); font-variant-numeric: tabular-nums; }
.answers li b { display: inline-block; min-width: 2.4em; margin-right: 4px; padding: 0 4px; font: 600 0.8rem var(--mono); text-align: center; border: 1px solid var(--ink); }
.answers li span:last-child { font: 0.85rem var(--mono); }
.answers li.mine { color: var(--accent); }

.help {
  width: min(640px, calc(100vw - 24px));
  height: min(760px, calc(100dvh - 24px));
  padding: 0;
  color: var(--ink);
  background: var(--surface);
  border: 2px solid var(--ink);
  font: inherit;
}
.help[open] { display: flex; flex-direction: column; }
.help::backdrop { background: rgb(0 0 0 / 0.45); }
.help-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 18px 20px 10px; }
.help-head h2 { font: 700 1.2rem/1.1 var(--text); margin: 0; }
.help input { margin: 0 20px; padding: 8px 10px; font: inherit; color: inherit; background: var(--surface); border: 1.5px solid var(--ink); border-radius: 0; }
.help input::placeholder { color: var(--faded); }
.help input:focus { outline: none; border-color: var(--accent); }
.help-intro { margin: 12px 20px 0; font-size: 0.85rem; color: var(--faded); }
.help-list { flex: 1; overflow-y: auto; padding: 0 20px 20px; margin-top: 12px; border-top: 1.5px solid var(--ink); }
.help-list h3 { margin: 18px 0 2px; font: 600 0.72rem var(--mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--accent); }
.help-group { margin: 6px 0 4px; font-size: 0.85rem; line-height: 1.5; }
.help-list article { padding: 10px 0; border-bottom: 1px solid var(--rule); }
.help-list article header { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; margin: 0; }
.help-list article header span { flex: none; font: 0.78rem var(--mono); color: var(--faded); }
.help-list article p { margin: 4px 0 0; font-size: 0.85rem; line-height: 1.5; }
.help-empty { margin: 18px 0; color: var(--faded); }

/* Phones: the sheet is the page, and the guess field sticks to the top. */
@media (max-width: 620px) {
  main { margin: 0; padding: 16px; width: 100%; border: 0; display: flex; flex-direction: column; }
  main > header { order: 0; gap: 4px 8px; flex-wrap: wrap; }
  main > header h1 { font-size: 1.3rem; }
  .status { font-size: 0.75rem; }
  .days { order: 1; }
  .entry { order: 2; position: sticky; top: 0; z-index: 2; margin: 0; padding: 6px 0 8px; background: var(--surface); }
  .message { order: 3; margin: 0 0 8px; }
  .board { order: 4; max-width: 100%; grid-template-columns: minmax(84px, 1fr) repeat(3, minmax(0, 1fr)); gap: 4px; }
  .label { font-size: 0.66rem; padding: 4px 2px; }
  .cell .symbol { font-size: 1.5rem; }
  .table-wrap { order: 6; margin-top: 10px; }
  .actions { order: 7; }
  .answers { order: 8; }
}