The main factor for header height is your logo. There is empty space in the image above and below the actual picture. You should be able to crop it in Shopify admin via “Edit image” button.
Crop as tight as you can – theme adds some vertical padding anyway…
As for the homepage transparent header, try this, in Customize:
- Add a 'Custom liquid"/“Custom code” section to the bottom of the “Template area” on the homepage.
- Paste this code
<style>
.main-bar:not(.sticky--active) {
filter: invert(1);
transition: all 0.5s;
z-index: 2;
}
</style>
