:root {
  --text: #1d1d1f;
  --muted: #5b5b66;
  --border: #c7c7cf;
  --accent: #0b6e4f;
  --error: #b3261e;
  --surface: #ffffff;
  --page: #f5f5f7;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

main {
  max-width: 28rem;
  margin: 0 auto;
  padding: 1.5rem 1rem 3rem;
}

h1 {
  margin: 0 0 1.25rem;
  font-size: 1.5rem;
}

.field {
  margin-bottom: 1rem;
}

label {
  display: block;
  margin-bottom: 0.25rem;
  font-weight: 600;
}

input {
  width: 100%;
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  background: var(--surface);
  color: inherit;
  font: inherit;
  font-size: 1.125rem;
}

input[aria-invalid="true"] {
  border-color: var(--error);
}

input:focus,
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.field-error {
  margin: 0.25rem 0 0;
  color: var(--error);
  font-size: 0.9375rem;
}

.field-error:empty {
  display: none;
}

.actions {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

button {
  flex: 1;
  padding: 0.75rem 1rem;
  border: 1px solid var(--accent);
  border-radius: 0.5rem;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}

button[type="submit"] {
  background: var(--accent);
  color: #fff;
}

#start-over {
  background: transparent;
  color: var(--accent);
}

#result {
  margin-top: 1.5rem;
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  background: var(--surface);
}

#result-tip,
#result-total {
  margin: 0 0 0.25rem;
}

#result-total {
  font-size: 1.125rem;
  font-weight: 700;
}

#result-shares {
  margin: 0.75rem 0 0;
  padding: 0.75rem 0 0;
  border-top: 1px solid var(--border);
  list-style: none;
  font-variant-numeric: tabular-nums;
}

#result-note {
  margin: 0.75rem 0 0;
  color: var(--muted);
}