:root {
  --bg: #0e1116;
  --bg2: #151a21;
  --bg3: #1c232c;
  --line: #2a333f;
  --line2: #3b4756;
  --fg: #dde3ea;
  --fg2: #97a3b1;
  --fg3: #6b7684;
  --accent: #6ea8fe;
  --accent2: #4d8ae0;
  --good: #58c08a;
  --bad: #e5675f;
  --warn: #e0a95c;
  --hypo: #b98ce0;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 14px/1.5 var(--sans);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* ---------------------------------------------------------------- top bar */
.topbar {
  display: flex; align-items: stretch; gap: 24px;
  padding: 10px 18px;
  background: linear-gradient(180deg, #171d25, #12171e);
  border-bottom: 1px solid var(--line);
  flex: 0 0 auto;
}
.brand h1 { margin: 0; font-size: 17px; letter-spacing: .2px; font-weight: 620; }
.brand .sub { margin: 2px 0 0; font-size: 12px; color: var(--fg3); max-width: 260px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.metrics { display: flex; gap: 10px; flex: 1; align-items: stretch; }
.metric {
  background: var(--bg2); border: 1px solid var(--line); border-radius: 8px;
  padding: 5px 10px; min-width: 92px; display: flex; flex-direction: column; justify-content: center;
}
.metric.wide { min-width: 190px; }
.mlabel { font-size: 10.5px; color: var(--fg3); text-transform: uppercase; letter-spacing: .5px; }
.mlabel em { font-style: normal; font-family: var(--mono); text-transform: none; color: var(--fg2); }
.mvalue { font-family: var(--mono); font-size: 17px; font-weight: 600; line-height: 1.2; }
.munit { font-size: 10px; color: var(--fg3); margin-left: 3px; }
.mbar { height: 3px; background: var(--bg3); border-radius: 2px; margin-top: 4px; overflow: hidden; }
.mbar > div { height: 100%; width: 0; background: linear-gradient(90deg, var(--good), var(--accent)); transition: width .3s; }

/* ------------------------------------------------------------------ layout */
.app { flex: 1; display: grid; grid-template-columns: minmax(430px, 560px) 1fr; min-height: 0; }
.pane { min-height: 0; display: flex; flex-direction: column; }
.pane.left { border-right: 1px solid var(--line); overflow-y: auto; }
.pane.right { min-width: 0; }

.controls { display: flex; gap: 6px; align-items: center; padding: 10px 14px 6px; flex-wrap: wrap; }
button {
  background: var(--bg3); color: var(--fg); border: 1px solid var(--line2);
  border-radius: 6px; padding: 5px 11px; font: inherit; font-size: 13px; cursor: pointer;
}
button:hover:not(:disabled) { background: #26303c; border-color: #4d5b6d; }
button:disabled { opacity: .4; cursor: default; }
button.primary { background: var(--accent2); border-color: var(--accent); color: #06101f; font-weight: 600; }
button.primary:hover:not(:disabled) { background: var(--accent); }
button.mini { padding: 2px 8px; font-size: 12px; }
.speed { margin-left: auto; font-size: 11.5px; color: var(--fg3); display: flex; align-items: center; gap: 6px; }
.speed input { width: 90px; }

.phasebar { display: flex; gap: 3px; padding: 2px 14px 8px; }
.phasebar span {
  font-size: 10.5px; padding: 2px 8px; border-radius: 20px; color: var(--fg3);
  border: 1px solid var(--line); background: var(--bg2); text-transform: uppercase; letter-spacing: .4px;
}
.phasebar span.on { color: #06101f; background: var(--accent); border-color: var(--accent); font-weight: 600; }

/* ------------------------------------------------------------------- board */
.boardwrap { padding: 4px 14px 8px; }
.board {
  display: grid; grid-template-columns: repeat(9, 1fr); aspect-ratio: 1;
  background: var(--line2); gap: 1px; border: 2px solid var(--line2); border-radius: 4px;
  user-select: none;
}
.cell {
  background: var(--bg2); position: relative; display: grid;
  grid-template-columns: repeat(3, 1fr); grid-template-rows: repeat(3, 1fr);
  cursor: pointer; overflow: hidden;
}
.cell.bt { border-top: 2px solid var(--line2); }
.cell.bl { border-left: 2px solid var(--line2); }
.cell.sel { outline: 2px solid var(--accent); outline-offset: -2px; z-index: 2; }
.cell.hypo { background: #241d33; }
.cell.elim { animation: flash .8s ease-out; }
@keyframes flash { from { background: #4a2a2a; } to { background: var(--bg2); } }

.cell .val {
  grid-column: 1 / 4; grid-row: 1 / 4; display: grid; place-items: center;
  font-family: var(--mono); font-size: clamp(15px, 3.2vw, 26px); font-weight: 600;
}
.cell.given .val { color: var(--fg); }
.cell.derived .val { color: var(--good); }
.cell.hypoval .val { color: var(--hypo); }

.cand {
  position: relative; display: grid; place-items: center;
  font-family: var(--mono); font-size: 9px; color: var(--fg3); line-height: 1;
}
.cand.off { visibility: hidden; }
.cand .bar { position: absolute; left: 1px; right: 1px; bottom: 0; background: var(--accent); border-radius: 1px; }
.cand .d { position: relative; z-index: 1; }
.cand.hot .d { color: #cfe2ff; font-weight: 600; }

.boardlegend { display: flex; gap: 12px; align-items: center; padding: 6px 2px 0; font-size: 11px; color: var(--fg3); }
.boardlegend .sw { display: inline-block; width: 9px; height: 9px; border-radius: 2px; margin-right: 4px; vertical-align: -1px; }
.sw.given { background: var(--fg); } .sw.derived { background: var(--good); }
.sw.hypo { background: var(--hypo); } .sw.elim { background: #7a3b3b; }
.grow { flex: 1; }
.chk { display: inline-flex; align-items: center; gap: 5px; cursor: pointer; }

/* --------------------------------------------------------------- cell info */
.cellinfo { margin: 4px 14px; background: var(--bg2); border: 1px solid var(--line); border-radius: 8px; padding: 9px 12px; }
.ci-head { font-size: 12px; color: var(--fg2); margin-bottom: 6px; }
.ci-head b { color: var(--fg); font-family: var(--mono); }
.bars { display: grid; grid-template-columns: repeat(9, 1fr); gap: 4px; align-items: end; height: 74px; }
.barcol { display: flex; flex-direction: column; justify-content: flex-end; height: 100%; gap: 3px; text-align: center; }
.barcol .b { background: linear-gradient(180deg, var(--accent), var(--accent2)); border-radius: 2px 2px 0 0; min-height: 1px; }
.barcol.zero .b { background: var(--line); }
.barcol .n { font-family: var(--mono); font-size: 10px; color: var(--fg3); }
.barcol .p { font-family: var(--mono); font-size: 9px; color: var(--fg3); height: 11px; }

/* --------------------------------------------------------------------- log */
.logwrap { padding: 6px 14px 16px; }
.logwrap h3 { font-size: 11px; text-transform: uppercase; letter-spacing: .6px; color: var(--fg3); margin: 6px 0; }
.log { margin: 0; padding: 0; list-style: none; font-size: 12px; max-height: 230px; overflow-y: auto; }
.log li { padding: 3px 8px; border-left: 2px solid var(--line2); margin-bottom: 2px; color: var(--fg2); background: var(--bg2); border-radius: 0 4px 4px 0; }
.log li .k { font-family: var(--mono); font-size: 10px; text-transform: uppercase; letter-spacing: .4px; margin-right: 6px; color: var(--fg3); }
.log li.t-contradiction { border-color: var(--bad); }
.log li.t-learn { border-color: var(--good); }
.log li.t-commit { border-color: var(--hypo); }
.log li.t-solution { border-color: var(--good); background: #16281f; color: var(--fg); }
.log li.t-backtrack { border-color: var(--warn); }
.log li.t-evaluate { border-color: var(--accent2); }

/* -------------------------------------------------------------------- tabs */
.tabs { display: flex; gap: 2px; padding: 8px 12px 0; border-bottom: 1px solid var(--line); flex: 0 0 auto; }
.tabs button { border: 1px solid transparent; border-bottom: none; border-radius: 6px 6px 0 0; background: transparent; color: var(--fg3); }
.tabs button.active { background: var(--bg2); border-color: var(--line); color: var(--fg); }
.tabpanes { flex: 1; min-height: 0; position: relative; }
.tabpane { position: absolute; inset: 0; display: none; flex-direction: column; overflow: auto; padding: 10px 14px 18px; }
.tabpane.active { display: flex; }
.tp-bar { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }
.hint { font-size: 11.5px; color: var(--fg3); }

/* -------------------------------------------------------------------- tree */
.treewrap { flex: 1; min-height: 260px; background: var(--bg2); border: 1px solid var(--line); border-radius: 8px; overflow: hidden; }
#tree { width: 100%; height: 100%; cursor: grab; display: block; }
#tree.drag { cursor: grabbing; }
.tnode rect { stroke-width: 1.4px; }
.tnode text { font-family: var(--mono); font-size: 10px; fill: var(--fg); pointer-events: none; }
.tnode .sub { font-size: 8px; fill: var(--fg3); }
.tedge { fill: none; stroke: var(--line2); stroke-width: 1.2px; }
.tedge.on { stroke: var(--accent); stroke-width: 2px; }
.tnode.st-open rect { fill: #232c37; stroke: var(--line2); }
.tnode.st-active rect { fill: #223247; stroke: var(--accent); }
.tnode.st-expanded rect { fill: #262034; stroke: #5c4a7a; }
.tnode.st-refuted rect { fill: #3a2222; stroke: var(--bad); }
.tnode.st-solved rect { fill: #1d3a2a; stroke: var(--good); }
.tnode.sel rect { stroke-width: 2.6px; stroke: #fff; }

.nodeinfo { margin-top: 8px; font-size: 12px; color: var(--fg2); background: var(--bg2);
  border: 1px solid var(--line); border-radius: 8px; padding: 8px 12px; min-height: 46px; }
.nodeinfo b { color: var(--fg); }
.nodeinfo .kv { display: inline-block; margin-right: 14px; font-family: var(--mono); font-size: 11px; }
.nodeinfo .kv span { color: var(--fg3); }

/* ------------------------------------------------------------ move analysis */
.moves table { width: 100%; border-collapse: collapse; font-size: 12px; }
.moves th { text-align: left; font-weight: 500; font-size: 10.5px; text-transform: uppercase;
  letter-spacing: .5px; color: var(--fg3); border-bottom: 1px solid var(--line); padding: 5px 7px; }
.moves td { padding: 5px 7px; border-bottom: 1px solid var(--bg3); vertical-align: middle; }
.moves tr.chosen { background: #1c2a3d; }
.moves tr.dead { background: #2c1c1c; }
.moves tr.dead td:first-child { box-shadow: inset 3px 0 0 var(--bad); }
.moves tr.chosen td:first-child { box-shadow: inset 3px 0 0 var(--accent); }
.moves .cellname { font-family: var(--mono); font-weight: 600; }
.moves .num { font-family: var(--mono); text-align: right; }
.branch { display: inline-flex; align-items: center; gap: 4px; font-family: var(--mono); font-size: 11px;
  padding: 1px 6px; border-radius: 10px; border: 1px solid var(--line2); background: var(--bg3); margin: 1px 3px 1px 0; }
.branch .pp { color: var(--fg3); font-size: 10px; }
.branch.ref { border-color: var(--bad); background: #33201f; color: #ffb4ae; text-decoration: line-through; }
.branch.win { border-color: var(--accent); background: #1e2f47; }
.branch.done { border-color: var(--good); background: #1c3226; }
.eerbar { height: 4px; background: var(--bg3); border-radius: 2px; overflow: hidden; min-width: 60px; }
.eerbar > div { height: 100%; background: var(--accent); }

/* ----------------------------------------------------------------- library */
.library { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 8px; margin-bottom: 14px; }
.pcard { background: var(--bg2); border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; cursor: pointer; }
.pcard:hover { border-color: var(--accent); }
.pcard.on { border-color: var(--accent); background: #1b2533; }
.pcard .nm { font-weight: 600; font-size: 12.5px; }
.pcard .meta { font-size: 10.5px; color: var(--fg3); margin-top: 2px; }
.pcard .note { font-size: 10.5px; color: var(--fg3); margin-top: 4px; line-height: 1.35; }
.badge { display: inline-block; font-size: 9.5px; text-transform: uppercase; letter-spacing: .5px;
  padding: 1px 5px; border-radius: 3px; margin-right: 5px; }
.badge.easy { background: #1e3a2a; color: #7fd6a4; }
.badge.medium { background: #1e3140; color: #7fbde0; }
.badge.hard { background: #3a3320; color: #dfc07a; }
.badge.expert { background: #3a2530; color: #e39ab8; }
.badge.extreme { background: #3a2020; color: #f0928a; }

h3 { font-size: 11px; text-transform: uppercase; letter-spacing: .6px; color: var(--fg3); margin: 12px 0 6px; }
.importbox textarea, .importbox input[type=url], input.mono {
  width: 100%; background: var(--bg2); color: var(--fg); border: 1px solid var(--line);
  border-radius: 6px; padding: 7px 9px; font-family: var(--mono); font-size: 12px; resize: vertical;
}
.row { display: flex; gap: 6px; align-items: center; margin: 6px 0; flex-wrap: wrap; }
.row input[type=url] { flex: 1; }
select { background: var(--bg3); color: var(--fg); border: 1px solid var(--line2); border-radius: 6px; padding: 5px 8px; font: inherit; font-size: 13px; }
.filebtn { background: var(--bg3); border: 1px solid var(--line2); border-radius: 6px; padding: 5px 11px; font-size: 13px; cursor: pointer; }
.filebtn input { display: none; }
.note { font-size: 11.5px; color: var(--fg3); margin: 6px 0; }
.note code { background: var(--bg3); padding: 1px 4px; border-radius: 3px; }
.err { color: var(--bad); font-size: 12px; min-height: 16px; margin: 4px 0; }

/* ------------------------------------------------------------------ editor */
.board.editor { max-width: 380px; }
.board.editor .cell { font-family: var(--mono); }
.board.editor .cell .val { font-size: 20px; }

/* --------------------------------------------------------------- benchmark */
.benchopts { display: flex; gap: 10px; flex-wrap: wrap; }
fieldset { border: 1px solid var(--line); border-radius: 8px; padding: 6px 10px 8px; margin: 0; }
legend { font-size: 10.5px; text-transform: uppercase; letter-spacing: .5px; color: var(--fg3); padding: 0 4px; }
fieldset label { display: block; font-size: 12px; margin: 2px 0; cursor: pointer; }
.benchout table { width: 100%; border-collapse: collapse; font-size: 12px; margin-top: 10px; }
.benchout th, .benchout td { padding: 4px 8px; border-bottom: 1px solid var(--bg3); text-align: right; }
.benchout th:first-child, .benchout td:first-child { text-align: left; }
.benchout th { color: var(--fg3); font-weight: 500; font-size: 10.5px; text-transform: uppercase; border-bottom: 1px solid var(--line); }
.benchout tr.grp td { background: var(--bg3); font-weight: 600; }
.benchout .best { color: var(--good); font-weight: 600; }
.benchout td.mono, .benchout th.mono { font-family: var(--mono); }

/* ------------------------------------------------------------------- about */
.about { max-width: 820px; font-size: 13px; color: var(--fg2); line-height: 1.62; padding-bottom: 40px; }
.about h2 {
  font-size: 14px; color: var(--fg); margin: 30px 0 8px; padding-top: 14px;
  border-top: 1px solid var(--line);
}
.about h2:first-child { margin-top: 0; padding-top: 0; border-top: none; }
.about h2 .num { color: var(--fg3); font-family: var(--mono); font-size: 12px; margin-right: 7px; }
.about h3 { font-size: 12.5px; color: var(--fg); margin: 16px 0 4px; text-transform: none; letter-spacing: 0; }

.about .lede { color: var(--fg3); font-style: italic; margin: 0 0 10px; }

/* table of contents */
.about .toc { background: var(--bg2); border: 1px solid var(--line); border-radius: 8px; padding: 10px 14px; margin: 0 0 8px; }
.about .toc ol { margin: 0; padding-left: 20px; columns: 2; column-gap: 26px; }
.about .toc li { margin: 1px 0; break-inside: avoid; }
.about .toc a { color: var(--accent); text-decoration: none; }
.about .toc a:hover { text-decoration: underline; }

/* glossary */
.about dl.gloss { display: grid; grid-template-columns: max-content 1fr; gap: 5px 16px; margin: 10px 0; align-items: baseline; }
.about dl.gloss dt { font-family: var(--mono); font-size: 12px; color: var(--fg); white-space: nowrap; }
.about dl.gloss dd { margin: 0; }
.about dl.gloss dt.sec { grid-column: 1 / -1; font-family: var(--sans); font-size: 11px; color: var(--fg3);
  text-transform: uppercase; letter-spacing: .5px; margin-top: 10px; border-bottom: 1px solid var(--line); padding-bottom: 3px; }

/* phase cards */
.about .phase { background: var(--bg2); border: 1px solid var(--line); border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0; padding: 9px 14px; margin: 9px 0; }
.about .phase h4 { margin: 0 0 4px; font-size: 12.5px; color: var(--fg); }
.about .phase h4 .tag { font-family: var(--mono); font-size: 10.5px; text-transform: uppercase; letter-spacing: .5px;
  background: var(--accent); color: #06101f; padding: 1px 7px; border-radius: 20px; margin-right: 8px; font-weight: 600; }
.about .phase p { margin: 4px 0; }
.about .phase .exit { font-size: 11.5px; color: var(--fg3); }
.about .phase.p-learn { border-left-color: var(--good); }
.about .phase.p-learn h4 .tag { background: var(--good); }
.about .phase.p-commit { border-left-color: var(--hypo); }
.about .phase.p-commit h4 .tag { background: var(--hypo); }
.about .phase.p-backtrack { border-left-color: var(--warn); }
.about .phase.p-backtrack h4 .tag { background: var(--warn); }

/* tables */
.about table { width: 100%; border-collapse: collapse; font-size: 12px; margin: 10px 0; }
.about th { text-align: right; font-weight: 500; font-size: 10.5px; text-transform: uppercase; letter-spacing: .5px;
  color: var(--fg3); border-bottom: 1px solid var(--line); padding: 5px 8px; }
.about th:first-child, .about td:first-child { text-align: left; }
.about td { padding: 4px 8px; border-bottom: 1px solid var(--bg3); text-align: right; font-family: var(--mono); }
.about td:first-child { font-family: var(--sans); }
.about tr.win td { color: var(--good); font-weight: 600; }
.about tr.lose td { color: var(--bad); }
.about caption { caption-side: bottom; font-size: 11px; color: var(--fg3); text-align: left; padding-top: 6px; }

/* caveat box */
.about .caveat { background: #241f1a; border: 1px solid #4a3a28; border-radius: 8px; padding: 9px 14px; margin: 10px 0; }
.about .caveat b { color: var(--warn); }
.about p { margin: 8px 0; }
.about code, .about .fml { font-family: var(--mono); font-size: 12px; background: var(--bg2); padding: 1px 5px; border-radius: 3px; color: var(--fg); }
.about .fml { display: block; padding: 9px 12px; margin: 8px 0; border-left: 2px solid var(--accent); border-radius: 0 4px 4px 0; white-space: pre; overflow-x: auto; }
.about ul { margin: 8px 0; padding-left: 20px; }
.about li { margin: 4px 0; }
.about strong { color: var(--fg); }

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: var(--line2); border-radius: 5px; border: 2px solid var(--bg); }
::-webkit-scrollbar-track { background: transparent; }

@media (max-width: 1100px) {
  .app { grid-template-columns: 1fr; overflow-y: auto; }
  body { overflow: auto; }
  .pane.right { min-height: 620px; }
  .tabpanes { position: static; }
  .tabpane { position: static; }
  .tabpane:not(.active) { display: none; }
}