:root {
  --paper: #eceee7;
  --ink: #1f2a36;
  --ink-soft: #4a5663;
  --thread: #b8322a;
  --brass: #c98f12;
  --board: #d7dfe2;
  --board-dot: #b7c3c8;
  --card: #f7f8f4;
  --rule: #c9cfc6;
  --serif: "Songti SC", "STSong", "SimSun", "Noto Serif CJK SC", "Source Han Serif SC", serif;
  --sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", system-ui, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #161c22;
    --ink: #e6e9e2;
    --ink-soft: #a9b3bb;
    --thread: #ef6b5e;
    --brass: #f0c04a;
    --board: #1f2a31;
    --board-dot: #34444c;
    --card: #1d252c;
    --rule: #33404a;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 17px/1.8 var(--sans);
  overflow-x: hidden;
}
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 12px; background: var(--ink); color: var(--paper); padding: 4px 10px; z-index: 5; }
a { color: inherit; }
:focus-visible { outline: 3px solid var(--brass); outline-offset: 3px; }

.masthead, main, .footer { width: min(1040px, 100% - 32px); margin-inline: auto; }

.masthead { position: relative; padding: 72px 0 40px; }
.thread-deco { position: absolute; inset: 40px 0 auto 0; width: 100%; height: 160px; pointer-events: none; }
.thread-deco path {
  fill: none; stroke: var(--thread); stroke-width: 2.4; stroke-linecap: round;
  stroke-dasharray: 1200; stroke-dashoffset: 1200;
  animation: draw 2.4s .2s cubic-bezier(.6,.1,.2,1) forwards;
}
@keyframes draw { to { stroke-dashoffset: 0; } }
.site-name {
  position: relative;
  margin: 0;
  font: 900 clamp(64px, 16vw, 168px)/1 var(--serif);
  letter-spacing: .06em;
}
.lede { position: relative; max-width: 34em; margin: 28px 0 0; color: var(--ink-soft); font-size: 18px; }

h2 { font: 700 30px/1.3 var(--serif); margin: 0 0 12px; }
h3 { font: 700 20px/1.4 var(--serif); margin: 0 0 8px; }

.board-section { padding: 24px 0 56px; }
.board-head { display: grid; gap: 4px 40px; grid-template-columns: auto 1fr; align-items: baseline; }
.hint { margin: 0; color: var(--ink-soft); font-size: 15px; max-width: 38em; }
.board {
  position: relative;
  margin-top: 16px;
  height: clamp(320px, 56vw, 520px);
  background-color: var(--board);
  background-image: radial-gradient(var(--board-dot) 1.2px, transparent 1.4px);
  background-size: 22px 22px;
  border-radius: 4px;
  box-shadow: inset 0 0 0 1px var(--rule);
  touch-action: none;
  cursor: crosshair;
}
canvas { display: block; width: 100%; height: 100%; }
.count { position: absolute; right: 12px; bottom: 8px; margin: 0; font-size: 13px; color: var(--ink-soft); pointer-events: none; }
.tools { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 14px; }
button {
  font: 600 15px/1 var(--sans);
  color: var(--ink);
  background: transparent;
  border: 1.5px solid var(--ink);
  border-radius: 999px;
  padding: 10px 18px;
  cursor: pointer;
}
button:hover { background: var(--ink); color: var(--paper); }

.index { padding: 24px 0 48px; border-top: 1px solid var(--rule); }
.index h2 { margin-top: 32px; }
.cards { list-style: none; padding: 0; margin: 24px 0 0; display: grid; gap: 28px 32px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); }
.card { position: relative; background: var(--card); padding: 26px 22px 20px 22px; border-left: 4px solid var(--thread); }
.card:nth-child(2n) { transform: rotate(.5deg); }
.card:nth-child(2n+1) { transform: rotate(-.4deg); }
.tab {
  position: absolute; top: -14px; right: 18px;
  width: 36px; height: 36px; display: grid; place-items: center;
  background: var(--brass); color: #1f2a36; border-radius: 50%;
  font: 700 17px/1 var(--serif);
}
.card p { margin: 0 0 8px; font-size: 16px; }
.lead-to { color: var(--thread); font-weight: 600; font-size: 15px !important; }

.how { padding: 32px 0 56px; border-top: 1px solid var(--rule); }
.how dl { display: grid; grid-template-columns: 6em 1fr; gap: 12px 24px; max-width: 44em; margin: 16px 0 0; }
.how dt { font: 700 19px/1.6 var(--serif); color: var(--thread); }
.how dd { margin: 0; }

.footer { padding: 28px 0 40px; border-top: 1px solid var(--rule); color: var(--ink-soft); font-size: 14px; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 24px; }
.footer p { margin: 0; }

@media (max-width: 600px) {
  body { font-size: 16px; }
  .masthead { padding-top: 48px; }
  .board-head { grid-template-columns: 1fr; }
  .how dl { grid-template-columns: 1fr; gap: 2px; }
  .how dd { margin-bottom: 12px; }
  .card:nth-child(n) { transform: none; }
}
@media (prefers-reduced-motion: reduce) {
  .thread-deco path { animation: none; stroke-dashoffset: 0; }
}