add css to only in mobile

@media (max-width: 768px) {
    .jeg_content p {
        font-family: “PT Serif”, Helvetica, Arial, sans-serif;
        font-size: 16px;
        margin: 0 0 1.25em;
        color: #333;
        font-size: 16px;
        line-height: 1.575em;
        word-break: normal;
        -ms-word-wrap: break-word;
        word-wrap: break-word;
    }
}