Make the sidebar menu slightly wider so the arrow
does not get pushed to the next line.
Also remove `text-transform: capitalize;` so we can have,
e.g., "Table of Contents" rather than "Table Of Contents".
With two entries of frequently encountered or obscured troubles so far:
- "Categories with accented characters" Unicode NFC/NFD mismatch
on Mac OS X (See #739)
- `hugo new` aborts with cryptic EOF error (See #776)
