:root {
  --bg: #f2f4f8;
  --card: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --primary: #2563eb;
  --danger: #dc2626;
  --border: #d1d5db;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 14px;
  position: sticky;
  top: 0;
  background: #fff;
  border-bottom: 1px solid var(--border);
  z-index: 10;
}

.topbar h1 {
  margin: 0;
  font-size: 1.1rem;
}

button {
  border: 1px solid var(--border);
  background: #fff;
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 0.95rem;
}

button.primary {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

button.danger {
  background: var(--danger);
  color: #fff;
  border-color: var(--danger);
}

.board {
  display: grid;
  grid-template-columns: repeat(4, minmax(250px, 1fr));
  gap: 12px;
  padding: 12px;
  overflow-x: auto;
}

.column {
  background: #e5e7eb;
  border-radius: 12px;
  min-height: 70vh;
  padding: 8px;
}

.column h2 {
  margin: 4px 4px 8px;
  font-size: 0.95rem;
}

.card-list {
  min-height: 60vh;
}

.card {
  background: var(--card);
  border-radius: 10px;
  border: 1px solid var(--border);
  padding: 10px;
  margin-bottom: 8px;
}

.card h3 {
  margin: 0 0 6px;
  font-size: 0.95rem;
}

.card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
  white-space: pre-wrap;
}

.card-form {
  width: min(520px, 92vw);
  display: grid;
  gap: 8px;
}

.card-form input,
.card-form textarea,
.card-form select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
}

.actions {
  margin-top: 8px;
  display: flex;
  gap: 8px;
  justify-content: flex-end;
}

.hidden { display: none; }

.footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
  padding: 16px;
}

@media (max-width: 900px) {
  .board {
    grid-template-columns: 1fr;
  }

  .column {
    min-height: auto;
  }

  .card-list {
    min-height: 100px;
  }
}