:root {
  --bg: #eef3f1;
  --ink: #14201c;
  --muted: #5f716b;
  --col: #ffffff;
  --line: #d5e1dc;
  --accent: #0b7a6a;
  --todo: #e8f2ef;
  --doing: #eef0f8;
  --done: #eef6e8;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", "Noto Sans TC", sans-serif;
  background: var(--bg);
  color: var(--ink);
  min-height: 100vh;
}
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.head {
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap;
  align-items: end; padding: 24px 20px 8px; width: min(1100px, 100%); margin: 0 auto;
}
.kicker { margin: 0; font-size: 12px; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
h1 { margin: 6px 0; font-size: clamp(1.6rem, 4vw, 2.2rem); }
.sub { margin: 0; color: var(--muted); }
.add-form { display: flex; gap: 8px; }
.add-form input {
  height: 40px; min-width: min(260px, 70vw); padding: 0 12px;
  border: 1px solid var(--line); font: inherit;
}
.add-form button {
  height: 40px; padding: 0 14px; border: 0; background: var(--accent); color: #fff;
  font: inherit; font-weight: 600; cursor: pointer;
}
.board {
  display: grid; gap: 14px;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  width: min(1100px, calc(100% - 24px)); margin: 16px auto 24px;
}
@media (max-width: 800px) {
  .board { grid-template-columns: 1fr; }
}
.column {
  background: var(--col); border: 1px solid var(--line); min-height: 280px;
  display: flex; flex-direction: column;
}
.column[data-status="todo"] { background: var(--todo); }
.column[data-status="doing"] { background: var(--doing); }
.column[data-status="done"] { background: var(--done); }
.column h2 {
  margin: 0; padding: 12px 14px; font-size: 15px; border-bottom: 1px solid var(--line);
  display: flex; justify-content: space-between;
}
.cards { display: grid; gap: 10px; padding: 12px; }
.card {
  background: #fff; border: 1px solid var(--line); padding: 12px;
  display: grid; gap: 8px;
}
.card strong { font-size: 14px; word-break: break-word; }
.card .actions { display: flex; flex-wrap: wrap; gap: 6px; }
.card button {
  border: 1px solid var(--line); background: #fff; font: inherit; font-size: 12px;
  padding: 4px 8px; cursor: pointer;
}
.empty { color: var(--muted); font-size: 13px; padding: 8px; }
.hint { width: min(1100px, calc(100% - 24px)); margin: 0 auto 40px; color: var(--muted); font-size: 13px; }