style.css

body {
    font-family: Arial, sans-serif;
    background-color: #f2f2f2;
}

h1 {
    text-align: center;
    color: #333;
}

form {
    width: 90%;
    height: 350px;
    max-width: 400px;
    margin: 0 auto;
    padding: 20px;
    border-radius: 10px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
}

input[type="text"] {
    display: block;
    width: 95%;
    margin: 0 auto;
    margin-bottom: 10px;
    padding: 10px;
    font-size: 24px;
    text-align: right;
    border: none;
    border-radius: 5px;
    background-color: #eee;
}

input[type="button"] {
    display: inline-block;
    width: 23%;
    margin: 0.5%;
    margin-bottom: 1%;
    padding: 10px;
    font-size: 20px;
    text-align: center;
    color: #fff;
    border: none;
    border-radius: 5px;
    background-color: #007bff;
    cursor: pointer;
}

input[type="button"]:nth-child(4n+1) {
    clear: left;
}

input[type="button"]:hover {
    background-color: #0062cc;
}

input[type="button"]:last-child {
    background-color: #dc3545;
    float: right;
}

.button-wrapper {
    float: right;
    margin-top: 10px;
}

@media (max-width: 600px) {
    form {
        padding: 10px;
    }

    input[type="text"] {
        font-size: 20px;
    }

    input[type="button"] {
        width: 48%;
        margin: 1%;
        margin-bottom: 2%;
    }

    input[type="button"]:nth-child(2n+1) {
        clear: none;
    }

    input[type="button"]:nth-child(4n+1) {
        clear: left;
    }
}