Using Variables when you change the standard design

You do not like the color scheme, font and sizes that Power Apps provides as “standard”. The Themes also do not exactly meet your needs. If you are going to make changes to the design, I recommend you go the extra effort and capture all of this at App OnStart in Variables.

To explain, I generally use a colour scheme around a base colour (generally a dark one) with various shades of ColorFade on different elements. If you set this base color as a Variable (as well as the more commonly used lighter ones), you simply refer to these in the elements of all the controls.

So for example (this is a really dark blue)

Set(varBaseCol,ColorFade(RGBA(9, 33, 98, 1),-30%));
Set(varBaseHover,ColorFade(varBaseCol,85%));
Set(varBaseShade,ColorFade(varBaseCol,90%));
Set(varBasePress,ColorFade(varBaseCol,30%));
Set(varBaseText,Black)

Sets the base, alternate row shade, pressed, hover and Text colours you can apply to all controls, so if in the future, you want the app to be Red, you simply change varBaseColor.

You can apply this logic to everything from particularly the colours above, to control heights and font type/sizes. If you are going to change them, seriously consider doing them in this way.