Hey Christian,

This actually fall under customization, as outlined in http://stackideas.com/support
However I can help you a bit on this. Perhaps, you can apply these css code in your custom.css file:

#es input.es-navbar__search-input {

    background-color: beige;

}



#es .es-navbar__body {

    background-color: antiquewhite;

}

Having said that, if you require us to perform the customization for you, you can always request for a quote from us at https://crm.stackideas.com and select "Customizations" . Our sales person would be glad to send you a quote for the customizations that you have requested.

Yes this is what I am doing. But every time there's an update, it's deleted.

I change here: components/com_easysocial/themes/wireframe/styles
styles.mini.css

Is this the right way to make these changes?

I would like to do a template override, to avoid this. How can I do?

You can follow the documentation here on how to make template override for the custom.css
https://stackideas.com/docs/easysocial/administrators/templating/adding-custom-css-codes

I have to create the folder: com_easysocial/css/custom.css
in /templates/protostar/html ???

Yes, that is correct, however, if you using another template you need to create the file accordingly
.../templates/[YOURCURRENTTEMPLATE]/html/com_easysocial/css/custom.css

I use the theme Wireframe of easysocial

For template override we do not specified the theme that currently used. Where it will called the custom.css first to be override the current theme css file