How to change Editor colors for PE?

You can easily change editor colors for SAE & MAE using CSS but for PE you can't change editor color using CSS, because it is overwritten by colors stored in database. From Siberian CMS PE v3.6, the colors of editor of the PE are stored in database.

You can find more details in below link: 

Below are tutorial how to change default Blue Color (#0099C7) for Siberian Flat Design?

Login to your Web Hosting Panel (like Plesk) and Click on Databases. You will see your Database list like below and click on Webadmin. (Click on image to enlarge it.)

This will open phpmyAdmin in new window. Find & Click on template_block.

Now change number of rows to 100/250.

Now find #0099C7 color on this page. (You can open findbar in Google Chrome by pressing CTRL + F buttons.)

You can see in above images that there are three matching value of #0099C7. (Like #0099C7 in color-blue, font-blue...) 

Make sure that For the Flat Design, you have to edit only blocks with type_id = 4.

Here you can change color code #0099C7 to your new one.

Now this customizations will change the color of  default #0099C7 to your new color in .color-blue & font-blue CSS classes used in editor.

Note: Be very careful while editing database, because every change couldn’t be undone, so it’s recommended to backup your table before editing.