- If you are referring to the Book Now button displayed on landing page under Our Rooms section, this section is displayed using the core module 'Display Hotel Rooms'.
Find the template at: qloapps_root_dir/modules/wkhotelroom/views/templates/hook/hotelRoomDisplayBlock.tpl
The changes that you are looking for can be made at line number 61 (may vary).
- The height of the black header strip can be changed either by setting a padding to the header elements or by changing height of the logo.
It seems you tried changing the default logo by replacing it which is located at: qloapps_root_dir/img/logo.jpg therefore the new image is using its own dimensions.
The best solution would be to redesign the logo in appropriate dimensions and upload it by modifying the current theme.
Theme logo can be uploaded at: Preferences > Themes > YOUR CURRENT THEME > LOGO Tab > Header logo