:root {
  --bg: #14161a;
  --panel: #1d2027;
  --line: #2e333d;
  --fg: #e7e9ee;
  --dim: #939aa8;
  --ok: #4ade80;
  --bad: #f87171;
  --accent: #7aa2f7;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 15px/1.5 ui-sans-serif, system-ui, sans-serif;
}
header {
  display: flex; align-items: center; gap: 16px;
  padding: 12px 20px; border-bottom: 1px solid var(--line);
}
h1 { font-size: 18px; margin: 0; letter-spacing: .08em; text-transform: uppercase; }
nav { display: flex; gap: 6px; }
button {
  font: inherit; color: var(--fg); background: var(--panel);
  border: 1px solid var(--line); border-radius: 6px; padding: 6px 12px; cursor: pointer;
}
button:hover { border-color: var(--accent); }
.tab.active { background: var(--accent); color: #10131a; border-color: var(--accent); }
a.tab, span.tab {
  text-decoration: none; display: inline-block; color: var(--fg); background: var(--panel);
  border: 1px solid var(--line); border-radius: 6px; padding: 6px 12px;
}
a.tab:hover { border-color: var(--accent); }
span.tab.active { background: var(--accent); color: #10131a; border-color: var(--accent); }
.mini { padding: 2px 8px; font-size: 12px; }
main { max-width: 720px; margin: 0 auto; padding: 24px 20px 60px; }
.mode.hidden { display: none; }
.bar { display: flex; align-items: center; gap: 16px; color: var(--dim); }
.bar label { cursor: pointer; }
.timer {
  margin-left: auto; font: 600 28px/1 ui-monospace, monospace;
  font-variant-numeric: tabular-nums; color: var(--fg);
}
.cards { display: flex; gap: 12px; justify-content: center; margin: 28px 0; flex-wrap: wrap; }
.card {
  width: 84px; height: 118px; border-radius: 10px; background: #f4f5f8; color: #16181d;
  border: 1px solid #c7cad2; position: relative; display: flex;
  align-items: center; justify-content: center; font: 700 34px/1 ui-serif, Georgia, serif;
  user-select: none;
}
.card.red { color: #d13b3b; }
.card .pip { position: absolute; top: 6px; left: 8px; font-size: 15px; font-weight: 600; }
.card .pip.br { top: auto; left: auto; bottom: 6px; right: 8px; transform: rotate(180deg); }
.answer {
  width: 100%; padding: 12px 14px; font: 18px ui-monospace, monospace;
  background: var(--panel); color: var(--fg);
  border: 1px solid var(--line); border-radius: 8px;
}
.answer:focus { outline: none; border-color: var(--accent); }
.answer:disabled { opacity: .5; }
.msg { min-height: 24px; margin: 10px 2px; font: 14px ui-monospace, monospace; }
.msg.ok { color: var(--ok); }
.msg.bad { color: var(--bad); }
.stats { margin-top: 32px; border-top: 1px solid var(--line); padding-top: 16px; }
table { border-collapse: collapse; width: 100%; font-variant-numeric: tabular-nums; }
th, td { text-align: left; padding: 4px 8px; border-bottom: 1px solid var(--line); }
th { color: var(--dim); font-weight: 500; font-size: 13px; }
td:not(:first-child) { font-family: ui-monospace, monospace; }
.hist-head { display: flex; align-items: center; gap: 10px; color: var(--dim); margin: 18px 0 6px; font-size: 13px; }
.hist { margin: 0; padding-left: 28px; max-height: 240px; overflow: auto; font: 13px ui-monospace, monospace; color: var(--dim); }
.hist li { padding: 2px 0; }
.hist li b { color: var(--fg); font-weight: 600; }
.hist li.dnf b { color: var(--bad); }
.result { margin-top: 20px; font: 14px ui-monospace, monospace; white-space: pre-wrap; }
footer { max-width: 720px; margin: 0 auto; padding: 0 20px 40px; color: var(--dim); font-size: 13px; }
footer code { background: var(--panel); padding: 1px 4px; border-radius: 4px; }
summary { cursor: pointer; }
.dim { color: var(--dim); }
#solve .bar { flex-wrap: wrap; margin-bottom: 12px; font-size: 13px; }
#v-list summary b { color: var(--fg); font-weight: 600; }
.equiv { margin: 4px 0 6px; padding-left: 18px; list-style: circle; }
#v-list { max-height: none; }
#v-list > li { position: relative; padding: 3px 0 3px 10px; }
#v-list > li.gap-after { margin-bottom: 10px; }
#v-list > li::before {
  content: ''; position: absolute; left: 0; top: 0; bottom: 0; width: 3px;
  background: linear-gradient(rgb(122 162 247 / var(--up)), rgb(122 162 247 / calc((var(--up) + var(--down)) / 2)) 50%, rgb(122 162 247 / var(--down)));
}
/* ---- train page ---- */
.hidden { display: none !important; }
.t-toolbar { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.t-field { display: flex; flex-direction: column; gap: 2px; font-size: 11px; color: var(--dim); text-transform: uppercase; letter-spacing: .06em; }
.t-toolbar select, .num {
  font: 14px ui-sans-serif, system-ui, sans-serif; color: var(--fg); background: var(--panel);
  border: 1px solid var(--line); border-radius: 6px; padding: 6px 28px 6px 10px; cursor: pointer;
  appearance: none; -webkit-appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--dim) 50%), linear-gradient(135deg, var(--dim) 50%, transparent 50%);
  background-position: calc(100% - 15px) 55%, calc(100% - 10px) 55%;
  background-size: 5px 5px; background-repeat: no-repeat;
  text-transform: none; letter-spacing: 0;
}
.t-toolbar select:hover, .t-toolbar select:focus { border-color: var(--accent); outline: none; }
.num { width: 5em; padding: 4px 8px; background-image: none; cursor: text; }
.t-menu { position: relative; align-self: flex-end; }
.t-menu summary {
  list-style: none; cursor: pointer; padding: 5px 12px; border: 1px solid var(--line);
  border-radius: 6px; background: var(--panel); color: var(--fg);
}
.t-menu summary::-webkit-details-marker { display: none; }
.t-menu[open] summary, .t-menu summary:hover { border-color: var(--accent); }
.t-menu-body {
  position: absolute; z-index: 10; top: calc(100% + 6px); left: 0; min-width: 230px;
  display: flex; flex-direction: column; gap: 8px; padding: 12px;
  background: var(--panel); border: 1px solid var(--line); border-radius: 8px;
  box-shadow: 0 8px 24px rgb(0 0 0 / .4); font-size: 13px;
}
.t-menu-body button, .t-file { text-align: left; }
.t-file { cursor: pointer; padding: 6px 12px; border: 1px solid var(--line); border-radius: 6px; }
.t-file:hover { border-color: var(--accent); }
.t-file input { display: none; }
.danger { color: var(--bad); }
.t-toolbar .timer { align-self: flex-end; }
.t-progress { color: var(--dim); font-size: 13px; margin-top: 12px; }
#t-cards { cursor: pointer; }
.card.back {
  background: repeating-linear-gradient(45deg, #34426b 0 6px, #2a3657 6px 12px);
  border-color: #4a5a8a;
}
.t-prompt { text-align: center; color: var(--dim); min-height: 24px; cursor: pointer; }
.t-answer { text-align: center; font: 15px ui-monospace, monospace; min-height: 24px; }
.t-answer .big { font: 700 22px/1.4 ui-sans-serif, system-ui, sans-serif; letter-spacing: .04em; }
.t-answer .ok { color: var(--ok); }
.t-answer .bad { color: var(--bad); }
.t-sols { list-style: none; padding: 0; margin: 8px 0 0; }
.t-grade { display: flex; gap: 12px; justify-content: center; margin-top: 16px; }
.t-grade button { min-width: 140px; padding: 10px 14px; }
.t-card-stats { text-align: center; color: var(--dim); font-size: 13px; margin-top: 12px; }
.t-filter-body { min-width: 320px; max-width: min(560px, calc(100vw - 32px)); gap: 12px; }
.t-filter.active summary { border-color: var(--accent); color: var(--accent); }
.t-fhead { display: flex; align-items: baseline; gap: 8px; color: var(--dim); font-size: 12px; margin-bottom: 4px; }
.t-fhead span { margin-right: auto; text-transform: uppercase; letter-spacing: .06em; font-size: 11px; }
.link { background: none; border: none; padding: 0; color: var(--accent); font-size: 12px; cursor: pointer; }
.chips, .t-fmode { display: flex; flex-wrap: wrap; gap: 4px; }
.t-fmode { margin-bottom: 6px; }
.chip { padding: 2px 8px; font-size: 12px; border-radius: 12px; color: var(--dim); }
.chip.on { background: var(--accent); border-color: var(--accent); color: #10131a; }
.t-ffoot { display: flex; justify-content: space-between; color: var(--dim); font-size: 12px; border-top: 1px solid var(--line); padding-top: 8px; }
@media (max-width: 640px) {
  .t-menu-body { position: fixed; top: 120px; left: 16px; right: 16px; min-width: 0; max-width: none; max-height: 70vh; overflow: auto; }
}
.t-field.disabled { opacity: .45; }
.t-field.disabled select { cursor: not-allowed; }
.t-toolbar .timer { margin-left: auto; }
.t-frange { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; font-size: 13px; color: var(--dim); }
.t-frange .num { width: 4.5em; }
/* ---- survey page ---- */
.s-bar { height: 4px; background: var(--panel); border-radius: 2px; margin-top: 10px; overflow: hidden; }
#s-fill { height: 100%; width: 0; background: var(--accent); transition: width .2s; }
#s-cards { cursor: pointer; }