:root {
  --bg: #333;
  --text: #333;
  --btn: #ccc;
  --big-btn: #3c3c3c;
  --shadow: rgba(0, 0, 0, 0.12);
}
* {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
  font-family: sans-serif;
}
main {
  background: var(--bg);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}
section {
  --bg-light: #fff;
  background: var(--bg-light);
  max-width: 320px;
  height: auto;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 20px;
  padding: 20px;
  border-radius: 20px;
}
#display {
  color: var(--text);
  font-size: 2em;
  text-align: end;
  padding: 10px;
  width: 100%;
  margin-top: 30px;
  border-radius: 30px;
  border: 1px solid rgb(245, 236, 236);
  box-shadow: 3px 4px 8px var(--shadow);
}
#display:focus {
  outline: none;
}
.container {
  display: flex;
  flex-direction: column;
  gap: 15px;
}
.grid1,
.grid2,
.grid3,
.grid4,
.grid5 {
  display: flex;
  justify-content: space-evenly;
}
.btn,
.btn-del {
  background: var(--bg-light);
  color: var(--text);
  font-size: 1em;
  font-weight: 600;
  text-align: center;
  height: 60px;
  width: 60px;
  padding: 20px;
  border-radius: 500px;
  border: none;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 3px 3px 10px var(--shadow);
}
.btn:hover,
.btn-del:hover {
  background: buttonface;
}
.eql {
  background: var(--big-btn);
  color: var(--bg-light);
}
.big-btn {
  font-size: 1em;
  font-weight: 600;
  padding: 20px 60px;
  border-radius: 30px;
  border: none;
  cursor: pointer;
  transition: background 0.3s ease, color 0.3s ease;
  box-shadow: 3px 3px 10px var(--shadow);
}
.big-btn:hover {
  background: buttonface;
  color: var(--text);
}
.btn-clr {
  background: var(--bg-light);
  color: var(--text);
}
.btn-clr:hover {
  background: buttonface;
}
.btn:active,
.big-btn:active,
.btn-clr:active,
.btn-del:active {
  background: var(--btn);
  transform: scale(0.75);
}