you can't

fortunately I am colour blind !

You can use CSS in a Formula field to change the colors. This changes the side bar color to grey...

html("
<style>
.HudContainer_root{background-color: grey;}
</style>
")

Herb,

It goes in a Formula field on your Form view and you can hide it. When I get a chance, I'll post the other CSS classes that you'll want to change.

Ok, I want to point out that this only works when you are working with one of your tables in your database and the Form view is active. It does not work for Table view (your database name), "Find" or "Calendar". Also, you can't hide the field using "Display field only, if:", you need to set the background color to match the background color of your form and set the "Label position" to "Hidden". Here is the code...

html("
<style>
.HudContainer_root{background-color: YourColor;}
.header{background-color: YourColor;}
.nav-item.selected{background-color: YourColor;}
.nav-item:hover{background-color: YourColor;}
</style>
")

I set up a table for selecting the colors dynamically using a Color field and a Formula field so I could see the value, but you could just use the 4 Color fields. Here is the code if you do that...

html("
<style>
.HudContainer_root{background-color: " + text(ColorField1) + ";}
.header{background-color: " + text(ColorField2) + ";}
.nav-item.selected{background-color: " + text(ColorField3) + ";}
.nav-item:hover{background-color: " + text(ColorField4) + ";}
</style>
")

If you have more than one table, I would create a user defined function in "Global script definitions" and use the function name in a Formula field in each of your tables. That way, you only have to change the colors in one location if you decide it's time for a change.

FORMULA FIELD. It is the first field you can select from "Create field"

Hi I am also very interested in getting rid of the blue/purple color but since I am an absolute novice I would very much appreciate if either of you or someone could write exactly how this is done. Thanks in advance! Colors are important! :-) 

Great! Thanks Sean for sharing.