Imported code into header now it's always showing

Hello!

I tried to inject some code into the header of my worksite to change social icon links...failed it! and now it's always visible in mobile and flashes up briefly in desktop when I load the site. I need to hide this obviously! 

Screen grab below. Any help appreciated-I'm a rookie and I dunno what I did!

If you're putting css in a header/footer or page injection point you need to wrap it in <style> </style> tags.
 

<style>
  //Your css here
</style>

If you insert the css into to custom css injection point you don't need the style tags.