style.css

    body {
        font-family: Arial, Helvetica, sans-serif;
        font-size: 18px;
        background-color: #efecec;
    }
    
    h3 {
        font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
        font-size: 26px;
        text-align: center;
        margin-top: 2%;
    }
    
    .container {
        height: 450px;
        width: 340px;
        border: none;
        margin: 5% auto;
    }
    
    textarea {
        height: 100px;
        width: inherit;
        font-size: 26px;
        text-align: end;
        text-decoration: none;
        background-color: #333333;
        color: white;
    }
    
    .calculator-body {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
        grid-template-rows: auto;
        /* width: inherit; */
    }
    
    button {
        height: 70px;
        width: 100%;
        font-size: 16px;
        border: 0.1px solid #e7e7e7;
        outline: none;
        font-size: 20px;
    }
    
    #zero {
        grid-column: 1 / 3;
    }
    
    .right-side {
        background-color: #278ea5;
        color: white;
    }
    
    .right-side:hover {
        background-color: #24788b;
    }
    
    .top-buttons {
        background-color: #f0f0f0;
    }
    
    .top-buttons:hover {
        background-color: #cccccc;
    }
    
    .number-body {
        background-color: #303a52;
        color: white;
    }
    
    .number-body:hover {
        background-color: #3d5181;
    }