Hello,

Please put the below CSS code to your theme Custom CSS box and let us know how it goes.

@media only screen and (max-width: 479px) {
.spb_box_text.coloured .box-content-wrap h1 {
    font-size: 18px;
}

.spb_box_text .box-content-wrap {
    padding: 15px;
}

}