:root {
  --background: #f6f6f6;
  --border: #ddd;
  --font: #222;
  --btn: #eee;
  --btn-hover: #ddd;
  --calculator-color: #808080;
  --display-color: #eee;
}

html {
  position: relative;
}

body {
  background-color: #48d1cc;
}

.main {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 75vh;
  min-height: 500px;
  padding: 10px;
  margin-top: 50px;
}

.calculator {
  width: 400px;
  border: 2px var(--border) solid;
  border-radius: 15px;
  padding: 20px;
  background-color: var(--calculator-color);
}

.display {
  padding: 10px 20px;
  border: 2px var(--border) solid;
  border-radius: 5px;
  margin-bottom: 20px;
  background-color: var(--display-color);
  text-align: right;
  word-wrap: break-word;
  word-break: break-all;
}

.history {
  min-height: 32px;
  font-size: 20px;
}

.current {
  min-height: 64px;
  font-size: 40px;
}

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

.span-2 {
  grid-column: span 2;
}

.btn {
  padding: 20px;
  border: 2px var(--border) solid;
  border-radius: 5px;
  background-color: var(--btn);
  font-size: 20px;
}

.btn:hover {
  background-color: var(--btn-hover);
}

.clearBtn {
  background-color: crimson;
}

.clearBtn:hover {
  background-color: firebrick;
}

.deleteBtn {
  background-color: gold;
}

.deleteBtn:hover {
  background-color: goldenrod;
}

/* Footer Style */

.footer {
  text-align: center;
  margin-top: 15px;
}

.footer-link {
  font-weight: bold;
  transition: all 0.2s;
}

.footer-link:hover {
  color: crimson;
  transition: all 0.2s;
}