Light gray box around pictures

Hello everyone, I am currently using the TIME theme, and every picture that I post on the page has a faint box around it that I would love to get rid of. The website is beta.leanwerks.com

From reading posts it looks like I need to edit the CSS. When I go to the style sheet editor it says I must go the data/css folder to edit. I have tried entering many so called fixes into the Custom CSS field with no luck. Where can I view the CSS and edit it? and what should I be changing or adding to get rid of those little boxes? Below I posted what is in the style sheet.

when I post the media in the pages it tries to post it as a link, I removed the link so its not linked to anything.

Any help would be appreciated.

Thanks.

/**
* Theme Name: Time
* Theme URI: https://themes.kubasto.com/time/
* Description: Time is a responsive, Retina-ready, premium WordPress theme.
* Author: Kuba Sto
* Author URI: https://themes.kubasto.com
* Version: 1.2.2
*/

/*
*
*/If you want to customize CSS, please place your code in the Custom CSS field in Theme Options / Advanced (so you won’t loose the changes after future theme updates).
* If you want to find the original CSS code, it’s in the data/css folder.