* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  background: #f3f4f6;
  color: #111827;
  display: flex;
  justify-content: center;
  padding: 3rem 1rem;
}

.card {
  width: 100%;
  max-width: 520px;
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  padding: 2rem;
  align-self: flex-start;
}

h1 { margin: 0 0 1.25rem; font-size: 1.75rem; }

form { display: flex; gap: 0.5rem; }

form input {
  flex: 1;
  padding: 0.7rem 0.9rem;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  font-size: 1rem;
}

form input:focus { outline: 2px solid #6366f1; border-color: transparent; }

form button {
  padding: 0 1.2rem;
  border: 0;
  border-radius: 8px;
  background: #6366f1;
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
}

form button:hover { background: #4f46e5; }

ul { list-style: none; margin: 1.25rem 0 0; padding: 0; }

li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.65rem 0.25rem;
  border-bottom: 1px solid #f0f0f3;
}

li label { display: flex; align-items: center; gap: 0.75rem; flex: 1; cursor: pointer; word-break: break-word; }

li input[type="checkbox"] { width: 1.1rem; height: 1.1rem; accent-color: #6366f1; }

li.done span { text-decoration: line-through; color: #9ca3af; }

.delete {
  border: 0;
  background: none;
  color: #9ca3af;
  font-size: 1.4rem;
  line-height: 1;
  cursor: pointer;
  padding: 0 0.4rem;
}

.delete:hover { color: #ef4444; }

.error { color: #b91c1c; margin: 0.75rem 0 0; }

.summary { color: #6b7280; font-size: 0.9rem; margin: 1rem 0 0; }