If search removes the header, how can I exit from search? Maybe making a Back/Cancel button/link would be a good idea.
Your browser has a back button The search results page leaves in the quick jump menu though that is actually a board specific setting and not everyone will have that turned on.
Maybe I went a little overboard hiding some of the necessities. I'll take another look at the skin this weekend and consider adding parts back in. For now though you can edit Dark-Pun.css:
/* Search
--------------------------------------------------------------*/
#brd-search #brd-head,
#brd-search #brd-visit,
#brd-search #brd-main #brd-crumbs-top,
#brd-search #brd-main #brd-crumbs-end,
#brd-search #brd-about,
#brd-search #brd-main .ct-box {display:none;}
Removing
#brd-search #brd-head,
from the above should do it