Make a full-width block

Site URL: https://www.shiyuportfolio.com/sonyc

Hi! My goal is  to add a full-width block background color by using code on this section (see attached image). I have some knowledges about HTML and CSS so I have no problem insert a background color, but the background color is not a full-width block, it has some padding in the left and right side that align with other contents. Can somebody helps to fix it? This is the URL of the site - https://www.shiyuportfolio.com/sonyc

also on the same site, wondering how to make this image full-width as well. 

Your site is not fullwidth, very time-consuming to set code block fullwidth.

First, remove margin/padding main#page id

Next, set Code Block background color

Then, set margin/padding for all elements, Except code block