Off canvas sidebars

Hello,

I need your help for two things :
Firstly, I need to include 2 sidebars on my website (one including the menu, the other a TOC). With the current configuration, when the window is shrunk, the sidebars contents appear after the entry content of the theme, which is not useful. I would like for those sidebars to appear with an off-canvas option, so that the user can read the menus on small devices (both left and right sidebars).

Moreover, I would like the excerpt of a search result page to be shown not from the beginning of the page, but where there is the searched word. That is to say to show in the excerpt the part of the page where the searched word is (and not the beginning of the page).

If you have any idea, thanks for your answer 🙂 .