You need a “child theme”
style.css for it –
/*
Theme Name: Corporate-lite Child
Description: Child Theme of corporate-lite
Author: Vlad
Template: corporate-lite
*/
@import url(“../corporate-lite/style.css”);
.header .logo h1{ color:#abcdef;}
Or just change style.css in theme, but you will lost changes after theme update
Or use Simple Custom CSS and JS module for it.
Or for logo – try create custom css in footer and paste it:
.header .logo h1{ display:none;}
.header {
background: url("https://assets.onestore.ms/cdnfiles/onestorerolling-1604-22001/shell/v3/images/logo/microsoft.png") no-repeat scroll left top rgba(0, 0, 0, 0);
}