Hello,
You can use "Front-end CSS File" or "Styles for the front-end", see this documentation to see how to proceed.
And here some explanations to understand how to build high priority css command :
1. First the minimum necessary to function properly :
Check that your selector is well written, good class (or Id) html and no mistake or typo
If your command is visible in your browser inspector tool, but is overridden (css command crossed out), then his priority isn't strong enough.
2. Now, some css priority system explanation :
From less to the highest priority :
.html_class_element {command: value}
.html_class_module .html_class_element {command: value}
.html_class_page .html_class_module .html_class_element {command: value}
.html_class_page .html_class_module .html_class_element {command: value !important;}
Note, that if
2 css commands have strictly the
same selector, then the
last written in the css file will be the one used.
Hope this will help you to achieve what you need.
Regards