style.css

html {
    height: 100%;
    width: 100%;
  }
  
  @import url('https://fonts.googleapis.com/css2?family=Poppins:wght@500&display=swap');
  
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
  }
  
  body {
    width: 100vw;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(45deg, #0a0a0a, #3a4452);
  }
  
  .calculator {
    border: 1px solid #717377;
    padding: 20px;
    border-radius: 16px;
    background: transparent;
    box-shadow: 0px 3px 15px rgba(113, 115, 119, 0.5);
  
  }
  
  input {
    width: 320px;
    border: none;
    padding: 24px;
    margin: 10px;
    background: transparent;
    box-shadow: 0px 3px 15px rgbs(84, 84, 84, 0.1);
    font-size: 40px;
    text-align: right;
    cursor: pointer;
    color: #ffffff;
  }
  
  input::placeholder {
    color: #ffffff;
  }
  
  button {
    border: none;
    width: 60px;
    height: 60px;
    margin: 10px;
    border-radius: 25%;
    background: transparent;
    color: #ffffff;
    font-size: 20px;
    cursor: pointer;
  }
  
  button:hover {
    background: #3a4452;
  }
  
  .equalBtn {
    background-color: #fb7c14;
  }
  
  .equalBtn:hover {
    background: #FF855C;
  }
  
  .operator {
    background: #E5E5E5;
    color: #18212a;
  }
  
  .operator:hover {
    background: #c7c7c7;
  }