style.css

/* 모든 요소의 기본 여백 제거 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* HTML과 Body의 기본 설정 */
html,
body {
  height: 100%;
}

body {
  display: flex;
  justify-content: center;
}

main {
  margin: 2rem;
  padding: 2rem;
  width: 70%;
  min-width: 500px;
  max-width: 800px;
  min-height: 500px;
  border-radius: 2rem;
  background-color: lightgray;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.window-btns {
  margin: 0 0.25rem 0.5rem;
  width: 20px;
  height: 20px;
  border-style: none;
  border-radius: 50%;
  transition: all 150ms ease-in;
}

.window-btns:hover {
  opacity: 0.7;
}

.window-btns:active {
  transform: scale(1.1);
}

.close {
  background-color: #ff5f54;
}

.minimize {
  background-color: #febd2f;
}

.full-screen {
  background-color: #2ac844;
}

/* Display */
.display {
  padding: 10px 30px;
  height: 30%;
  border: 1px solid black;
  border-bottom: none;
  border-radius: 2rem 2rem 0 0;
  background-color: #323232;
  overflow: hidden;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
}

.history {
  color: #9b9b9b;
  font-size: 2rem;
  text-align: right;
}

.current {
  margin-top: 20px;
  color: white;
  font-size: 5rem;
  text-align: right;
}

.delete {
  width: 75px;
  height: 75px;
  border: none;
  border-radius: 50%;
  position: absolute;
  top: 10%;
  left: 25px;
  /* display: none; */
}

/* Buttons */
.buttons {
  height: 70%;
  border-radius: 0 0 2rem 2rem;
  display: flex;
  flex-wrap: wrap;
  overflow: hidden;
}

.btn {
  width: 25%;
  border: 1px solid lightgray;
  background-color: #fff;
  font-size: 1.5rem;
}

.zero {
  width: 50%;
}

.top-center {
  border-left: 1px solid white;
  border-right: 1px solid white;
}

.delete:hover,
.btn:hover {
  background-color: #9b9b9b;
}

.delete:active,
.btn:active {
  background-color: #323232;
  color: white;
}

.function {
  background-color: #d4d4d2;
}

.operator,
.calculate {
  background-color: #f5923e;
  color: white;
}