* {
  margin: 0;
  padding: 0;
}

html, body {
  height: 100vh;
  width: 100%;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: #b7936d;
}

:root{
  --bg: #0e0e0e;
  --panel: #ffffff;
  --digit: #2a2323;
  --op: #cfcfcf;
  --accent: #b7f135;
  --text: #ffffff;
  --text-dark: #0e0e0e;
  --gap: 8px;
  --radius: 18px;
}

#housing{
  width: 320px;
  height: 560px;
  background: var(--bg);
  border: 2px solid #1a1a1a;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-auto-rows: 64px;
  grid-template-rows: 96px repeat(5, 1fr);
  gap: var(--gap);
  padding: var(--gap);
  border-radius: var(--radius);
  box-sizing: border-box;
  box-shadow: 0 12px 28px rgba(0,0,0,.35); 

#display-area{
  grid-column: 1 / -1;
  background: var(--panel);
  color: var(--text-dark);
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding: 12px 16px;
  font-size: 1.6rem;
  border-radius: calc(var(--radius) - 6px);
}

.calc{
  background: var(--digit);
  color: var(--text);
  border: 0;
  border-radius: 999px;
  font-size: 1rem;
  min-width: 48px;
  min-height: 48px;
  display: grid;
  place-items: center;
  transition: transform .06s ease, background-color .12s ease;
}

.operators{ background: var(--op); color: var(--text-dark); font-weight: 700; }
#equals{ background: var(--accent); color: var(--text-dark); font-weight: 800; }

.calc:hover{ transform: translateY(-1px); }
.calc:active{ transform: translateY(0); }

.calc:focus-visible{
  outline: 3px solid rgba(255,255,255,.8);
  outline-offset: 2px;
}
}