Headline cut off in Mobile

Hello Everyone,

My Headline is almost cut off in one of my pages in mobile view. I tried make it smaller with the following code but it did not change the headline:

@media screen and (max-width:640px) {
header#header * {
    font-size: 10px;
    text-align: justify;
    text-align-last: left;
}
}

Any help would be much appreciated. Thank you in advance!

Difficult to help without site url.

Each template will have different mobile header class.