Linear-gradient() warning in skyblue/dhtmlx.css using Angular

Hello, I am using the skin skyblue in a TreeGrid using Angular.

However, I get warnings from postcss-loader such as:

WARNING in ./node_modules/dhtmlx/5.0/skins/skyblue/dhtmlx.css (./node_modules/@angular-devkit/build-angular/src/angular-cli-files/plugins/raw-css-loader.js!./node_modules/postcss-loader/src??embedded!./node_modules/dhtmlx/5.0/skins/skyblue/dhtmlx.css)
Module Warning (from ./node_modules/postcss-loader/src/index.js):
Warning

(9:225979) Gradient has outdated direction syntax. New syntax is like to left instead of right.

It seems that linear-gradient() is causing many warnings because of “to left/right” or “to bottom/top”.

Is there a way to fix this warning?

Thank you for your note. Unfortunately we’re not planning to update these css in the near time, but we’ll definitely update it in the next release.
For now I may suggest you only to attach the dhtmlx css bypassing the postcss.