Fix invalid CSS selector on Windows
Fix invalid CSS selector on Windows

I didn't check whether this affects anything. The rule was being ignored
previously.

gracile-fr/zotero,rmzelle/zotero,fbennett/zotero,aurimasv/zotero,LinuxMercedes/zotero,retorquere/zotero,LinuxMercedes/zotero,sendecomp/zotero,sendecomp/zotero,hoehnp/zotero,egh/zotero,egh/zotero,adunning/zotero,adunning/zotero,sendecomp/zotero,rmzelle/zotero,robamler/zotero,gracile-fr/zotero,retorquere/zotero,gracile-fr/zotero,robamler/zotero,egh/zotero,LinuxMercedes/zotero,retorquere/zotero,hoehnp/zotero,rmzelle/zotero,robamler/zotero,hoehnp/zotero,adunning/zotero