We are glad to know that you considered using Basel for your web-site. I hope you will be happy with it.
The logo height is limited by header height option. Try to increase it in Theme Settings -> Header -> Header layout. Also, you have some empty white space on the logo and we suggest you to remove it (cut the image and reupload). And 3000x3000 is too large and bad for performance. Try to upload 300×300 for example.
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