styles.css

body {
    background-color: #1f1f1f;
    color: #ffffff;
    font-family: Arial, sans-serif;
}

.gr-form input[type="text"],
.gr-form select {
    background-color: #333333 !important;
    border: 1px solid #777777 !important;
    color: #ffffff !important;
}

.gr-output {
    background-color: #333333 !important;
    border: 2px solid #777777 !important;
    border-radius: 5px;
    padding: 10px;
    margin-top: 20px;
}

.gr-control.gr-number input {
    width: 100px !important;
}