I noticed a weird bug after a bit of digging.
As I go through local squid cache proxy, if Via header is included, chan's layout is messed up. The culprit turned out to be, that it tries to get style.htm instead of style.css for some reason. The current workaround is either:
via off
or for more fine-grained approach:
acl sankaku dstdomain .sankakucomplex.com
request_header_access Via deny sankaku

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