Can´t resize canvas to maximum width

Design help General
1

Hey, why can’t I drag the canvas (in the Designer) to the maximum width? I´m on a Mac Book Pro 15". Thanks for your help!

This videos show´s my problem

Bildschirmfoto 2020-07-19 um 12.56.10
Bildschirmfoto 2020-07-19 um 12.56.102880×1452 283 KB

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

2

Okay I fixed it. When you unpin the navigator it works.