Google Search Box in Sidebar widget

I’m trying to add a Google search bar to the sidebar. This is what it’s supposed to look like: –

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After pasting the code into online html viewers etc they all show it this way. However… When I put it into the html widget in the sidebar, I get this: –

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It’s weird. If I type something random in the html widget then there are no borders. Also, again if I put the google search html somewhere else then it acts as it should. It is only when they are combined that I get these horrible borders around and inside it. Can anyone help?

Here’s the homepage I’m having problems with: https://englishxp.co.uk

The page I need help with: [log in to see the link]