Customizing Single Post Page and Search Page

Hi! I’m wondering if it is possible to customize the single post page and the search page for my website.

https://stg3.utahwebhosting.net/why-kids-shouldnt-wear-bulky-coats-in-car-seats/
https://stg3.utahwebhosting.net/?s=asdsa

If you look at these pages on the website, I want to override the green container and conform it to the color of the main background on that page. I want to change the search page’s background color to a light blue and change the green container to a light blue as well.

Is this possible? Thanks in advance!