‘Site identity’ customisation: logo (image) and site title (text)

I know this is a very common forum subject, but I haven’t found a working solution so far for the Hava theme.

Overall it’s a great theme, and exactly what I need; thanks for your work on it. The only thing I can’t get right yet is the ‘site identity’ customisation, particularly the logo options (above the menu bar).

At the moment, as you can see, I just have the site title at the top of each page, and that’s a great size and also shows clearly on desktop, tablet and mobile views. My ideal scenario would be to keep the size and font of the site title, but just add my logo to the left of the words.

However, if I make an image that looks like that and use it as the logo, it’s very small and seems to ‘fuzz’ (i.e. decrease in quality). I have seen the suggestion for an image 150 x 58 pixels, but whatever size image I use in that ratio, it always comes out the same.

Is there a piece of code you can suggest that would allow an uploaded image to take up the same space as the site title currently does (i.e. when there’s no logo specified under ‘customise > site identity), and how should I best ensure that such an image will look as crisp, or almost, as the site title does now?

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