style.css

body {
  margin: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  margin-left: 5px;
  color: black;
  text-decoration: none;
}

.header {
  display: flex;
  justify-content: center;
  align-items: center;
  flex: 1;
  font-family: 'Orbitron', sans-serif;
  font-weight: 400;
  font-size: 50px;
  background-color: #1a1c1b;
  color: #cfcf6d;
}

.main {
  display: flex;
  justify-content: center;
  flex: 5;
  background-color: #1a1c1b;
}

.container {
  display: flex;
  flex-direction: column;
  height: inherit;
  width: 500px;
  margin-bottom: 10px;
  border: 10px solid #b39c7e;
  border-radius: 3%;
}

.container .screen {
  background-color: #9fa91f;
  height: 100px;
  display: flex;
  align-items: center;
  direction: rtl;
  font-weight: 900;
  font-size: 80px;
  border: 5px solid black;
  font-family: 'Quattrocento Sans', sans-serif;
  overflow: auto;
}

.buttonsContainer {
  display: flex;
  flex: 1;
  gap: 5px;
}

.buttonsContainer .leftSide,
.buttonsContainer .rightSide {
  gap: 5px;
  display: flex;
  flex-direction: column;
  flex: 1;
}

.block.operand {
  background-color: #90989a;
  color: black;
}

.operator {
  background-color: #68574d;
}

.block.operand:hover {
  background-color: #263e44;
}

.block.operand:active {
  background-color: #263e44;
}

.operatorClicked {
  background-color: #dba281;
}

.row {
  display: flex;
  flex: 1;
  gap: 5px;
}

.rowLeft {
  flex-direction: row-reverse;
}

.block {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Poppins', sans-serif;
  font-weight: bold;
  font-size: 40px;
  color: white;
  cursor: pointer;
  border: none;
  border-radius: 15%;
}

.block:active {
  transform: scale(0.9);
}

.footer {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 18px;
  font-family: arial, sans-serif;
  color: #70757a;
  padding: 15px;
}