Put the previous file in your configured folder and active it. Felicitation! Each canvas will get the following class & attribute : .canvas-file[data-canvas-file*="filepath"].
You can now stylize it using these state. For example, to change the canvas-color for a file named ProjectOne
:
body.canvas-file[data-canvas-file*="ProjectOne"] {
--canvas-color-1: 138,97,189 ; /* Mapple Street*/
--canvas-color-2: 110,151,23; /*Oak Street*/
--canvas-color-3: var(--color-yellow-rgb);
--canvas-color-4: 154,80,40; /* Pine Street*/