Hello Bern (@BernSh) 
You could ask Mike Pasini (@mrpasini) for help on coding your own Palette with HTML - he has posted Macros in the past which are using Custom coded Palettes.
I’ve tagged him to jump in here - I’m really sure he will provide you useful Code you could use to make your own.
Greetings from Germany 
Tobias
[jumping in]
It's true that when you find the basic UI options in Keyboard Maestro limiting, the answer is the HTML Prompt action (which is not restricted to using forms). You can style them with CSS and expand their functionality with JavaScript.
I've contributed many examples of that in my own contributions here but I realize adapting that to one's own situation can be daunting. But if you see something you like in those examples (which usually include screen shots of the HTML), let me know your specifics and I'll see what I can conjure up.
Thank you! Indeed Mike has!
Backatcha from the US 
Bern
Mike, thank you for your generous offer!
The picture show palettes in the tool & side bars in Mail.
Could we rebuild them as HTML windows that:
1. keep the same background (or allow pickable colors) and text colors (or allow pickable colors),
2. let us change text size in the vertical bar, and
3. let us scale images in the horizontal bar?
Today, palette dimension ratios are fixed, making text and icons density fixed. Independent height and width controls would let us resize each dimension, keep triggers aligned, and make the initial layout far easier.
Pick a color for each background (I'll show you how to change it).
Tell me what size you want the text to be (and supply that text, please).
How big do you want that text to be? Can it overwrite what's underneath it?
I see a horizontal palette at the top (whose icons, I guess, link to Keyboard Maestro actions) and a vertical palette on the side that looks like a list of Mail Folders. It would be nice to have samples of those palettes to work with (not the real ones but smaller ones derived from them as examples).
It also looks like you have the Keyboard Maestro Applications Palette running on the left side along with another mysterious one-button palette you've outlined in red. Neither of these are involved?
It also seems you are overlaying these palettes on the Mail interface or some window of it. (i don't use Mail myself so again I'm guessing). Overwriting what's underneath as you resize these palettes might be a problem. It would, in any case, be helpful to know the functions of the horizontal palette's actions.
The more accurately we can define the specifications, the less work it's going to be.
Can I PM you to set up a screen share to walk you through the pieces and design? It'd be a lot easier and more efficient.
I'm still going to need answers to my specific questions (and the sample palettes), Bern. So let's start there to see if I can help you at all.
Yes these are all Keyboard Maestro palettes linked to Keyboard Maestro actions. The horizontal palette style is icons that link to Keyboard Maestro actions and the vertical palette style is text of the macros
Yes the macros cover all the Mail's tool and side bars. The mysterious one-button palette hides all palettes resurfacing the native Mail interface.
I've annotated the pic with all the actions and their functions and am including a bunch of measures in case we get far enough to need them.
The "TF/TEM" in the upper left corner is shows/hides a palette mostly filled with "Insert Text by Pasting" actions and a few premade emails templates. Nothing fancy.
Let me know if these descriptions are enough or if you still want palettes samples.
Thank you for considering this project!
Well, the immediate problem I see is that you have a fixed palette space within which you want to enlarge your text and images. HTML isn't going to help with that. More likely you should redesign your icons.
For example, for the six that select a mailbox, you could use a solid background color with larger text. Everything else on that palette seems sufficiently large in your screen shot (and I'm squinting with double vision at the moment).
You could do some menu reorganization but it appears you prefer discrete buttons for every action (rather than, say, drop down menus for the horizontal menu or fly-outs from the vertical menu). You could put all of your app activation macros under one drop down in the horizontal palette to eliminate that vertical palette, as an example. But it you want buttons for them that won't fly, I'm guessing.
Then there's the issue (which you've no doubt resolved) of what happens when you move the Mail window (you don't, I suspect). The palettes stay where they were put.
So I suspect you aren't moving or resizing the window and the opaque backgrounds of the palettes overlay the Mail interface. Dan's Sticky Palettes would allow you to move your existing palettes outside the window to let you move the window and have the Mail interface available (and eliminate the need for toggling visibility of your main palettes).
So for the AS macros that copy emails to folders, you could use larger font sizes by expanding the width of the Mail window and eating up the new space with a wider palette. Or just eliminate the two vertical palettes to its left as suggested above. But then you'd see fewer destinations at a time.
Those changes would allow you to enlarge your custom text and images without resorting to an HTML palette or two, I believe. (But if you want to continue this discussion, I have a feeling we should start a new thread.)
Right, we've moved a tad from coloring palettes. New thread if you're up for it or call it here. My interest, your time, your call.
