*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  font: 1rem/1.4 system-ui, sans-serif;
}

main {
  max-width: 32rem;
  margin: 0 auto;
  padding: 1rem;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

h1 {
  font-size: 1.25rem;
  margin: 0 0 1rem;
}

form {
  margin: 0;
}

button,
input {
  font: inherit;
}

form.add,
li.edit form {
  display: flex;
  gap: 0.5rem;
}

form.add input,
li.edit input {
  flex: 1;
  min-width: 0;
}

form.add input.qty,
li.edit input.qty {
  flex: 0 0 5rem;
}

ul {
  list-style: none;
  margin: 1rem 0;
  padding: 0;
}

li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

li input[type="checkbox"] {
  width: 1.75rem;
  height: 1.75rem;
}

li label {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

li.done label {
  text-decoration: line-through;
}

.error {
  color: red;
}