.numpad-content {
    width: 400px;
}

.numpad-content input {
    font-size: 30px;
    line-height: 50px;
    height: 50px;
    text-align: center;
    letter-spacing: 5px;
}

.numpad-content .row {
    margin-bottom: 10px;
}

.numpad-content .btn-numpad {
    font-size: 2.5em;
    width: 100%;
}

.numpad-content .btn-numpad i {
    font-size: inherit;
}