:root {
  --paper: #ffffff;
  --ink: #1a1815;
  --ink-soft: #625d56;
  --rule: #e2dfd8;
  --light-sq: #f0d9b5;
  --dark-sq: #b58863;
  --illegal: #6b6b6b;

  --START: #a8321f;
  --START-tint: #f4d4c8;
  --SQUARE: #2c6a4b;
  --FILE: #2a5988;
  --RANK: #9b6710;
  --DIAGONAL: #773a72;
  --PIECE: #5b4636;
  --CLAIM: #625d56;
  --CHECK: #c0392b;
  --ATTACKS: #2a5988;
  --FLIGHT: #9b6710;
  --WINS: #2c6a4b;
  --v-true: #2c7a4b;
  --v-false: #c0392b;
  --v-unknown: #8a8580;

  --body: "Newsreader", Georgia, serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  --radius: 4px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font: 400 18px/1.55 var(--body);
  min-height: 100vh;
}

.desk {
  max-width: 1240px;
  margin: 0 auto;
  padding: 32px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 440px;
  gap: 40px;
  align-items: start;
  padding-top: 48px;
}
.panel { display: grid; gap: 16px; min-width: 0; animation: rise 0.7s 0.08s cubic-bezier(0.2, 0.8, 0.2, 1) both; }

/* ---------- examples ---------- */

.examples { display: flex; flex-wrap: wrap; gap: 8px; }
.example {
  font: 400 12px/1 var(--mono);
  padding: 7px 10px;
  border: 1px dashed var(--ink-soft);
  border-radius: 999px;
  background: transparent;
  color: var(--ink-soft);
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}
.example:hover, .example.is-active { background: var(--ink); color: var(--paper); border-color: var(--ink); border-style: solid; }
.example:focus-visible { outline: 2px solid var(--FILE); outline-offset: 2px; }

/* ---------- the text ---------- */

.text-frame {
  position: relative;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  box-shadow: 0 1px 2px rgba(26, 24, 21, 0.04), 0 16px 36px -26px rgba(26, 24, 21, 0.28);
  overflow: hidden;
}
.text {
  min-height: 360px;
  padding: 22px 26px;
  font: 400 20px/2 var(--body);
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  outline: none;
  caret-color: var(--START);
}
.text-frame:focus-within { border-color: var(--ink-soft); }

.loader { position: absolute; left: 0; right: 0; bottom: 0; height: 3px; background: var(--rule); }
.loader span {
  display: block;
  height: 100%;
  width: calc(var(--progress, 0) * 100%);
  background: var(--START);
  transition: width 0.2s;
}
.loader.is-error span { width: 100%; background: var(--illegal); }

.text.is-fresh .mk { animation: stamp 0.35s cubic-bezier(0.2, 1.4, 0.4, 1) both; } /* not while typing */
/* ---------- marks: what the tagger found ---------- */
.mk {
  --c: var(--ink);
  color: inherit;
  background: transparent; /* <mark> is yellow by default */
  border-radius: 3px;
  cursor: pointer;
  transition: opacity 0.18s, box-shadow 0.18s;
}
.mk--move { --c: var(--START); font: 600 0.84em/1 var(--mono); padding: 0.18em 0.32em; white-space: normal; }
.mk--move.mk--chosen { background: var(--START); color: var(--paper); }
.mk--move.mk--considered { background: var(--START-tint); color: var(--START); box-shadow: inset 0 -2px 0 var(--START); }
.mk--move.mk--rejected { background: var(--START-tint); color: var(--START); text-decoration: line-through; text-decoration-color: color-mix(in srgb, var(--START) 55%, transparent); }
.mk--fact {
  --c: var(--FILE);
  text-decoration: underline solid var(--ink-soft);
  text-decoration-thickness: 2px;
  text-underline-offset: 5px;
}
.mk--ref { cursor: default; }
.mk--loc { color: var(--c); font-weight: 600; }

/* ---------- the chess.js layer: verdict colours and badges ---------- */
.col-check { display: none; }
.show-check .col-check { display: revert; }
.show-check .mk--fact[data-verdict="true"] { text-decoration-color: var(--v-true); }
.show-check .mk--fact[data-verdict="false"] { text-decoration-color: var(--v-false); text-decoration-style: wavy; }
.show-check .mk--fact[data-verdict="unknown"] { text-decoration-color: var(--v-unknown); text-decoration-style: dotted; }
.show-check .mk[data-badge]::after {
  content: attr(data-badge);
  font: 700 0.62em/1 var(--mono);
  vertical-align: super;
  margin-left: 2px;
  text-decoration: none;
  display: inline-block;
}
.show-check .mk[data-verdict="true"]::after { color: var(--v-true); }
.show-check .mk[data-verdict="false"]::after { color: var(--v-false); }
.show-check .mk[data-verdict="unknown"]::after { color: var(--v-unknown); }
.show-check .mk--move.mk--chosen[data-verdict]::after { color: var(--paper); }
.show-check .mk--move[data-verdict="false"] { box-shadow: inset 0 0 0 2px var(--v-false); }

.text.has-focus .mk:not(.is-lit):not(.mk--ref) { opacity: 0.28; }
.mk.is-lit { box-shadow: 0 0 0 2px var(--paper), 0 0 0 4px var(--c); }
.mk--ref.is-lit { background: color-mix(in srgb, var(--FILE) 14%, transparent); }

/* ---------- the report ---------- */
.report { border-top: 1px solid var(--rule); padding-top: 14px; font-size: 15px; line-height: 1.5; }
.report__head { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px; }
.report h2 { margin: 0; font: 600 18px/1.2 var(--body); }
.report h3 { margin: 16px 0 6px; font: 600 11px/1 var(--mono); text-transform: uppercase; letter-spacing: 0.06em; color: var(--ink-soft); }
.report p { margin: 0; }
.report .counts { margin-top: 6px; font: 400 13px/1.4 var(--mono); }
.muted { color: var(--ink-soft); }
.toggle { display: inline-flex; border: 1px solid var(--rule); border-radius: 999px; overflow: hidden; }
.toggle button {
  font: 400 12px/1 var(--mono); padding: 7px 11px; border: 0; background: transparent; color: var(--ink-soft); cursor: pointer;
}
.toggle button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
.toggle button:focus-visible { outline: 2px solid var(--FILE); outline-offset: -2px; }
.v { font: 700 13px/1 var(--mono); }
.v--true { color: var(--v-true); }
.v--false { color: var(--v-false); }
.v--unknown { color: var(--v-unknown); }
.lines { margin: 0; padding: 0; list-style: none; display: grid; gap: 6px; }
.tag { font: 400 11px/1 var(--mono); padding: 3px 6px; border-radius: 999px; border: 1px solid var(--rule); color: var(--ink-soft); }
.tag--chosen { border-color: var(--START); color: var(--START); }
.chip { font: 600 12px/1 var(--mono); padding: 3px 6px; border-radius: 3px; background: var(--START-tint); color: var(--START); cursor: pointer; }
.chip--chosen { background: var(--START); color: var(--paper); }
.chip--rejected { text-decoration: line-through; }
.show-check .chip--illegal { background: repeating-linear-gradient(-45deg, #eeeeee 0 5px, #e2e2e2 5px 10px); color: var(--illegal); box-shadow: inset 0 0 0 1px var(--v-false); }
.show-check .chip--unknown { box-shadow: inset 0 0 0 1px var(--v-unknown); }
.facts { width: 100%; border-collapse: collapse; font-size: 14px; }
.facts th { text-align: left; font: 400 11px/1 var(--mono); color: var(--ink-soft); padding: 4px 6px; border-bottom: 1px solid var(--rule); }
.facts td { padding: 6px; border-bottom: 1px solid var(--rule); vertical-align: top; }
.facts tr[data-mark] { cursor: pointer; }
.facts tr.is-current td, .facts tr[data-mark]:hover td { background: #f6f4ef; }
.kind { font: 400 11px/1 var(--mono); color: var(--ink-soft); margin-right: 4px; }
.facts td:nth-child(2) { white-space: nowrap; font: 400 12px/1.5 var(--mono); }
.facts td.col-check { font: 400 12px/1.5 var(--mono); }

.legend { display: flex; flex-wrap: wrap; gap: 6px 14px; margin: 0; font-size: 14px; color: var(--ink-soft); }
.legend .mk { cursor: default; }
.legend__group { font: 400 11px/1 var(--mono); text-transform: uppercase; letter-spacing: 0.06em; }

.fen { display: grid; gap: 4px; }
.fen__label { font: 400 12px/1 var(--mono); color: var(--ink-soft); }
.fen input {
  width: 100%;
  font: 400 13px/1.4 var(--mono);
  padding: 8px 10px;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  color: var(--ink);
  background: var(--paper);
}
.fen input:focus { outline: 2px solid var(--FILE); outline-offset: 1px; }
.fen input[aria-invalid="true"] { border-color: var(--START); background: var(--START-tint); }
.span--SQUARE { --c: var(--SQUARE); }
.span--FILE { --c: var(--FILE); }
.span--RANK { --c: var(--RANK); }
.span--DIAGONAL { --c: var(--DIAGONAL); }
.span--SQUARE, .span--FILE, .span--RANK, .span--DIAGONAL {
  color: var(--c);
  font-weight: 600;
  padding: 0 0.12em;
  background: linear-gradient(transparent 52%, color-mix(in srgb, var(--c) 26%, transparent) 52%, color-mix(in srgb, var(--c) 26%, transparent) 92%, transparent 92%);
}

/* ---------- board ---------- */

.board-frame {
  position: sticky;
  top: 24px;
  padding: 14px 14px 26px 26px;
  background: #3a2f22;
  border-radius: var(--radius);
  box-shadow: 0 30px 50px -30px rgba(28, 25, 21, 0.7), inset 0 0 0 1px rgba(255, 255, 255, 0.06);
  animation: rise 0.7s 0.16s cubic-bezier(0.2, 0.8, 0.2, 1) both;
}
.board {
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  grid-template-rows: repeat(8, minmax(0, 1fr)); /* fixed rows: contents can't stretch a square */
  aspect-ratio: 1;
  container-type: inline-size;
}
.sq { position: relative; display: grid; place-items: center; min-width: 0; min-height: 0; }
.sq--light { background: var(--light-sq); }
.sq--dark { background: var(--dark-sq); }
.sq::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--lit, transparent);
  opacity: 0;
  transform: scale(0.6);
  transition: opacity 0.2s, transform 0.25s cubic-bezier(0.2, 1.4, 0.4, 1);
  transition-delay: calc(var(--d, 0) * 30ms);
}
.sq.is-lit::after { opacity: 0.62; transform: scale(1); }
.sq.is-from { box-shadow: inset 0 0 0 100vmax rgba(168, 50, 31, 0.22); }
.sq.is-to { box-shadow: inset 0 0 0 100vmax rgba(168, 50, 31, 0.42); }
.sq__piece {
  position: absolute; /* fills the square exactly, so every piece sits dead centre */
  inset: 4%;
  z-index: 1;
  background: center / contain no-repeat;
}
.sq__file, .sq__rank { position: absolute; font: 600 10px/1 var(--mono); color: #d8c9a8; }
.sq__file { bottom: -18px; left: 50%; transform: translateX(-50%); }
.sq__rank { left: -17px; top: 50%; transform: translateY(-50%); }
.sq__step {
  position: absolute; /* out of the grid flow, so the square keeps its size */
  z-index: 2;
  top: 3%;
  right: 3%;
  min-width: 34%;
  height: 34%;
  padding: 0 3%;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: var(--START);
  color: #fff;
  font: 600 3.4cqw/1 var(--mono);
  animation: stamp 0.35s cubic-bezier(0.2, 1.4, 0.4, 1) both;
}

footer {
  max-width: 1240px;
  margin: 0 auto;
  padding: 8px 32px 40px;
  font: 400 13px/1 var(--mono);
  color: var(--ink-soft);
}
footer a { color: var(--ink); text-underline-offset: 3px; }
footer a:hover { color: var(--START); }

/* ---------- motion ---------- */

@keyframes rise { from { opacity: 0; transform: translateY(14px); } }
@keyframes stamp { from { opacity: 0; transform: scale(1.35); } }

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

/* ---------- small screens ---------- */

@media (max-width: 1000px) {
  .desk { grid-template-columns: 1fr; }
  .board-frame { position: static; max-width: 460px; }
  .text { min-height: 220px; }
}
@media (max-width: 560px) {
  .desk, footer { padding-left: 18px; padding-right: 18px; }
}