body {
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #ffffff;
  height: 100vh;
  font-family: "Times New Roman", Times, serif;
  user-select: none;
}

.calculator {
  text-align: center;
  width: 250px;
  background: #333;
  padding: 10px;
  border-radius: 5px;
  box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.9);
}

input {
  padding: 15px;
  margin: 10px;
  width: 80%;
}

#display,#history {
  width: 80%;
  height: 30x;
  font-size: 1em;
  text-align: right;
  padding: 10px;
  border: none;
  outline: none;
  background: #b6b6b6;
  color: rgb(0, 0, 0);
  border-radius: 5px;
  margin-bottom: 10px;
}

.clr {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 5px;
  margin: 10px;
}

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

.numbers {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.btn-clr {
  background: #edff47;
  outline: none;
  border: none;
  border-radius: 20px;
  padding: 7px;
}

.btn {
  background: #a7a7a7;
  outline: none;
  border: none;
  border-radius: 20px;
  padding: 7px;
}

.btn-num {
  background: #ffffff;
  outline: none;
  border: none;
  border-radius: 20px;
  padding: 7px;
  display: grid;
}

.btn:hover,
.btn-clr:hover,
.btn-num:hover {
  opacity: 0.5;
  transition: 0.1s;
  box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.5);
}

.btn:active,
.btn-clr:active,
.btn-num:active {
  transform: scale(0.85);
  transition: 0.2s;
  box-shadow: 0px 4px 10px rgba(0, 0, 0, 0.9);
}