Hi Kevin,
Are you using a wordpress caching plugin? If so please check if clearing or purging cache solves the issue.
If the blue box styling is still not working it’s because the woocommerce version 3.5.1 is not yet compatible with the current theme version. The latest supported woocommerce version is 3.4.5.
With that said I can think of two ways to solve this problem, you can roll back to the latest supported woocommerce version or just add this to your global CSS for a temporary fix while the version is still not compatible .
.woocommerce-notices-wrapper {
background-color: #d9edf7;
color: #3a87ad;
margin-bottom: 1.313em;
border: 1px solid #b3d1ef;
padding: 0.786em 1.25em 1em 1.15em;
font-size: 14px;
line-height: 1.5;
}
Hope this helps.
Thanks!