* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
  font-family: "OPen Sans", sans-serif;
}

/* Utility */
.flex {
  display: flex;
  justify-content: center;
  align-items: center;
}

.container {
  min-height: 100vh;
  background: linear-gradient(rgba(0, 0, 0, 0.664), rgba(252, 48, 218, 0.3));
}

#calculator {
  width: min(100%, 500px);
  height: 100vh;
  background: #eaedef;
/*   border-radius: 16px; */
  box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
}

#result {
  height: 20%;
/*   border: 5px solid rgb(0, 0, 0);
  border-top: none;
  border-bottom: none; */
  border-top-left-radius: 16px;
  border-top-right-radius: 16px;
}
#history {
  height: 35%;
  border-bottom: 1px solid #000000;
  /* border: 1px solid blueviolet; */
  position: relative;
}
#history-value {
  color: #919191;
  position: absolute;
  right: 8%;
  top: 35%;
}
#output {
  /* border: 1px solid greenyellow; */
  height: 65%;
  position: relative;
}
#output-value {
  font-size: 3rem;
  position: absolute;
  bottom: 0;
  right: 8%;
}

.keyboard {
/*   border: 5px solid rgb(0, 0, 0);
  border-top: none;
  border-bottom: none; */
  width: 100%;
  height: 80%;
  flex-direction: column;
  justify-content: space-between;
  align-items: unset;
  padding: 6px;
  border-bottom-left-radius: 16px;
  border-bottom-right-radius: 16px;
}
.button-set {
  justify-content: space-between;
}
.number,
.operator {
  border: 0;
  width: 75px;
  height: 75px;
  /* flex-basis: 40%; */
  border-radius: 50%;
  font-weight: bold;
  font-size: 1.8rem;
  cursor: pointer;
}
.number {
  opacity: 0.6;
  border: 1px solid #bbbaba;
}
.number:active,
.operator:active {
  transform: scale(0.9);
}
.equal {
  flex: 1;
  border-radius: 8px;
}
.keyboard > .button-set:nth-child(1) > button:nth-child(1),
.keyboard > .button-set:nth-child(1) > button:nth-child(2),
.keyboard > .button-set:nth-child(1) > button:nth-child(3) {
  background-color: rgba(226, 226, 226, 0.966);
}

.keyboard > .button-set:nth-child(1) > button:nth-child(3) {
  font-size: 2.2rem;
  font-weight: 600;
  background-color: #dd72dda8;
}
.keyboard > .button-set:nth-child(1) > button:nth-child(4) {
  font-size: 3rem;
  font-weight: 500;
  background-color: #20b2aa;
}
.keyboard > .button-set:nth-child(2) > button:nth-child(4) {
  font-size: 2.6rem;
  font-weight: 500;
  background-color: #ffa500;
}
.keyboard > .button-set:nth-child(3) > button:nth-child(4) {
  font-size: 2.6rem;
  font-weight: 500;
  background-color: #f08080;
}
.keyboard > .button-set:nth-child(4) > button:nth-child(4) {
  font-size: 2.6rem;
  font-weight: 500;
  background-color: #7d93e0;
}
.keyboard > .button-set:nth-child(5) > button:nth-child(2) {
  font-size: 2.8rem;
  font-weight: 500;
  background-color: #9477af;
}