How do I center my header as well as my categories on my product page?

Site URL: https://www.helloshelbyalvarez.com/

The code i used but isn't working was :

/* center shop title */

h2.nested-category-title.nested-category-title-padding {

    text-align: center !important;

    -webkit-box-pack: center;

        -ms-flex-pack: center;

            justify-content: center;

}

Hi. What is site access password?