calc.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #211f1f;
}

.calculator {
    background-color: lightgrey;
    padding: 20px;
    box-shadow: 5px 10px 20px rgba(0, 0, 0, 0.5);
    border-radius: 15px;
    border: 2px solid black;
    width: 340px;
    display: inline-block;
}

.calculator input[type="button"] {
    width: 60px;
    height: 60px;
    font-size: 18px;
    margin: 5px;
    border: 2px solid black;
    outline: none;
    cursor: pointer;
    background-color: #f0f0f0;
    border-radius: 30px;
    box-shadow: 5px 10px 20px rgba(241, 238, 238, 0.964);
    color: black;
}

.calculator input[type="button"][value="C"] {
    width: 100%;
    margin: 5px 0;
    background-color: green;
}

.calculator input[type="text"] {
    width: 280px;
    height: 50px;
    font-size: 24px;
    text-align: right;
    margin-bottom: 10px;
    border: 2px solid black;
    outline: none;
    padding: 5px;
    border-radius: 30px;
    background-color: #f0f0f0;
}