[Theme: Adelle] Widget Area Not Wide Enough For Ads

Greetings!

I am using the Adelle theme on my self-hosted WordPress site: https://69.195.124.60/~southsp3/

The gray widget area on the right side of my site is causing me a couple of issues:

1. It is not wide enough for standard affiliate ads (which are typically 300 px x 250 px). Notice how the Amazon ads at the bottom of the gray strip are getting cut off.

I have tried modifying the attributes of the widget-area selector in the style.css file. This is the bit of code I have been tweaking:

.site-main .widget-area {
float: right;
margin: 0 2% 1.875em 0;
width: 29.411764705%;
}

I was able to make the widget area wider to accommodate the ad size by modifying ‘width: 29.411764705%;’ but this does not fix the ad display on my mobile phone (ads are still getting cut off); it only solved the problem when I viewed my site on my laptop.

2. Another issue is that those zig-zag lines that separate each widget section in the widget area repeat strangely on my mobile phone. I’d actually like to remove those and replace them with something else. Any insight on this would be greatly appreciated, though this is sort of a secondary issue; I am more concerned with getting my ads to display properly within the widget area.

Many thanks!