* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  background: #1c1c1e;
  font-family: system-ui, sans-serif;
}

.calc {
  width: 320px;
  padding: 16px;
  background: #000;
  border-radius: 16px;
}

.display {
  height: 80px;
  padding: 0 8px;
  display: flex;
  align-items: flex-end;
  justify-content: flex-end;
  color: #fff;
  font-size: 48px;
  overflow: hidden;
}

.sci {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-top: 12px;
}

.sci button { height: 48px; font-size: 20px; background: #1f3a5f; }

.keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-top: 12px;
}

button {
  height: 64px;
  border: 0;
  border-radius: 12px;
  background: #333;
  color: #fff;
  font-size: 24px;
  cursor: pointer;
}

button:active { filter: brightness(1.3); }

.fn { background: #a5a5a5; color: #000; }
.op { background: #30d158; }
.eq { background: #30d158; }
.tall { grid-row: span 2; height: auto; }
.wide { grid-column: span 3; }