Creating single page versus index with panels - which is best practice?

Site URL: https://mobile-mentor.com

Looking for guidance on best practice for site creation. We are a B2B IT services company. We have productized services, which we promote on one page each.

Currently, we are treating each service as an index, then creating 'panels' in that service to hold the various sections of information we want to show to our customers. Content aside, what is the best practice for creating pages vs indexes?

We have setup the current schema due to the desire to stick to the styling provided by a firm, which includes soft gray backgrounds on some panels and navy blue backgrounds on others, with white being the most common.

We cannot find a way to adhere to that background setup without creating indexes and using panels with CSS to set the background color. 

Is this a bad practice? What effects will this have on SEO, maintenance, otherwise? Is this innocuous and really a choice?

Is there a workaround to get part of a page to have a full background color while leaving the rest of the page intact?

https://www.mobile-mentor.com

I don't think there is such a thing as a bad practice. There are just different approaches to get the look you want. If you find what works use it. If it takes code to do it then we should be grateful that SS is set up to do that, take custom css, makes things a whole lot easier than when I was building sites using Publisher and other programs that is for sure. 

As far as a background color workaround, you can use a background image quite easily on a single page in most templates. That image can be one solid color if you want. I have used single image background myself a few times, site wide and just for one page. The latter takes a bit of code using my template.