:root {
  --max: 840px;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  max-width: var(--max);
  margin: 2rem auto;
  padding: 0 1rem;
  line-height: 1.5;
}

header h1 {
  margin: 0 0 0.25rem 0;
}

.sub { margin: 0 0 1.5rem 0; }

.card {
  border: 1px solid #ddd;
  border-radius: 10px;
  padding: 1rem;
  margin: 0 0 1rem 0;
}

.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.75rem;
}

label {
  display: grid;
  gap: 0.35rem;
}

input {
  padding: 0.6rem 0.7rem;
  border: 1px solid #ccc;
  border-radius: 8px;
  font-size: 1rem;
}

.row {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1rem;
  flex-wrap: wrap;
}

button {
  padding: 0.65rem 0.9rem;
  border: 1px solid #333;
  border-radius: 8px;
  background: white;
  cursor: pointer;
  font-size: 1rem;
}

.results {
  display: grid;
  gap: 0.75rem;
}

.label { font-size: 0.9rem; opacity: 0.75; }
.value { font-size: 1.4rem; font-weight: 700; }
.small { font-size: 0.95rem; }

.muted { opacity: 0.7; }

.assumptions { margin-top: 1rem; }

footer {
  margin-top: 1.5rem;
  font-size: 0.9rem;
}

@media (min-width: 720px) {
  .grid {
    grid-template-columns: 1fr 1fr;
  }
  .results {
    grid-template-columns: 1fr 1fr;
  }
  .results > div:last-child {
    grid-column: 1 / -1;
  }
}