@Genesys Social Media,
I believe the main color used in that theme is :
You simply need to apply you change with say #fb0808 or whichever red you have to see if that is what you require.
Your browser "Web developer" tools can assist in doing that before actually making a permanent change in a "TRY BEFORE YOU CHANGE" test
In order to apply only a few cosmetic changes I recommend making use of this component: