* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  outline: none;
  font-family: "Noto Sans", sans-serif;
}

html {
  font-size: 62.5%;
}

.container {
  width: 100%;
  height: 100vh;
  background-color: #1e2224;
  display: flex;
  justify-content: center;
  align-items: center;
}

.calculator {
  width: 40rem;
  height: 60rem;
  background-color: #2e2f30;
  padding: 3rem 2rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  border-radius: 2rem;
  box-shadow: 0 1rem 3rem rgba(0, 0, 0, 0.4);
}

.screen {
  width: 34rem;
  height: 8rem;
  background-color: #8d8d8d;
  margin-bottom: 1.5rem;
  border-radius: 1rem;
  border: none;
  pointer-events: none;
  text-align: right;
  font-size: 2rem;
  letter-spacing: 0.1rem;
  color: #fff;
  padding: 2rem;
}

.btn,
.equal {
  width: 7rem;
  height: 7rem;
  margin: 1rem;
  border: none;
  background: linear-gradient(180deg, #2f2f2f, #3f3f3f);
  box-shadow: inset -0.8rem 0 0.8rem rgba(0, 0, 0, 0.15),
    inset 0 -0.8rem 0.8rem rgba(0, 0, 0, 0.25), 0 0 0 0.2rem rgba(0, 0, 0, 0.75),
    1rem 2rem 2.5rem rgba(0, 0, 0, 0.4);
  border-radius: 1rem;
  cursor: pointer;
  position: relative;
}

.btn:active,
.equal:active {
  filter: brightness(1.5);
}

.clear {
  width: 25rem;
  background: #d62929;
}

.btn::before,
.equal::before {
  content: attr(data-num);
  position: absolute;
  top: 0.3rem;
  left: 0.4rem;
  bottom: 0.7rem;
  right: 1.2rem;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 2.2rem;
  border-radius: 1rem;
  background: linear-gradient(90deg, #2d2d2d, #4d4d4d);
  box-shadow: -0.5rem -0.5rem 1.5rem rgba(0, 0, 0, 0.1),
    1rem 0.5rem 1rem rgba(0, 0, 0, 0.15);
  border-left: 0.1rem solid #0004;
  border-bottom: 0.1rem solid #0004;
  border-top: 0.1rem solid #0009;
}

.clear::before {
  background: #d62929;
  border-left: 0.1rem solid #fff4;
  border-bottom: 0.1rem solid #fff4;
  border-top: 0.1rem solid #fff4;
}

.equal {
  background: #37925a;
}

.equal::before {
  background: #37925a;
  border-left: 0.1rem solid #fff4;
  border-bottom: 0.1rem solid #fff4;
  border-top: 0.1rem solid #fff4;
}