Adding a summary block duplicates banner bg image

Site URL: http://www.trondheimopen.org/

I added a summary block showing a carousel of different upcoming events to my site and the summary block added a duplicate banner background image which doesn't seem to follow the same rules as the first image.

If i delete the summary block the duplicate image disappears.

I am very confused, please help me.

Here's the (likely very broken) code for the banner.
 

Quote

header {
      position: fixed;
      height:200px;
      top: -50px;
      z-index: 99;
      width: 100% !important;
      background:rgba(255, 255, 255, 0);
      background-image: url("https://static1.squarespace.com/static/574ca513d51cd43e7b85ab28/t/5f00ab37f65fdc5e99e3aa5d/1593879353085/Header-bg4.png");
      background-position: center;
      background-repeat: no-repeat;
      background-size: contain;
}

Have you solved this yet?