In fact, the problem is in the mobile menu (I was calling categories). The background of the mobile menu does not appear every time. I put an image to see if it corrected, and did not correct.

The site link is this: eletronicoimportado.com

I uploaded the images to another service. Here’s what I’m going to try to explain. I noticed that there is an image in conjunction with a demo theme on the mobile theme of the demo tech theme: https://imgur.com/T4ZlcIj.
Then I went to my website and saw that a gradient appeared too, which is what I want, so there is no confusion: https://imgur.com/r7jmp3j
However, this gradient does not remain. When you refresh the page, it looks the same as I reported: https://imgur.com/9SekzqG

I hope you understood my problem. I’m using Google Translate, so there may be a bit of confusion.

Well, I noticed that the demo has a background in the categories and then I went back to see my site and noticed a gradient appeared, but it disappeared again.

Other problems have appeared here. I’m having problems with some thumbnails (the posts have pictures but are not recognized in the thumbnail) and the body images in the post are with a blur

Another question, how to remove or change the name of these categories?