Brand Color for Text Selection

Changes the highlight color when visitors select text on your site to match your brand.

Code

::selection {
    background: #2271b1;
    color: #ffffff;
}

Change the two colors. Keep enough contrast between background and text.

Install WPIDE on your WordPress site (it is free) and open Code Snippets.
Use snippet above adds it from the library in one click. Or copy the code into a new snippet with the same code type.
It is added inactive: review the code and settings, then switch it on.