Shrink sticky menu/remove white spaces

Hello, Could you please help with the following. I have a child theme and here is my url https://backpackfullofmaps.com/ 1. I would like to remove the white gaps between some sections. eg before "latest from the blog" and "watch . our adventures" section? 2. I have downloaded a plugin to create the sticker header however is very large when scrolling. How can i shrink the menu when scrolling so it does not take up half the page? Thank you in advance :)