Custom Header Logo via WordPress Customizer [Image Quality]


I love this theme, I almost managed to customize it to match my preferences, but can’t solve this issue:

I want to replace the Header Text, which is the blog’s name, with my Logo. But the problem is, if I upload a logo of 300px by 76px, it loses quality. Is there any way to upload a bigger and proportional image, which will be resized automatically to match de 300x76 dimensions?

I have little experience in coding, and hope my english is good enough to be understood.

Thank you very much!

Solved! Just added this piece of code to the Custom CSS.

#logo img {
    width: 300px;
    height: 76px;