Htmlv2 style

Various fixes.
Looks a bit different now: file:///home/buck/trees/mine/MySQLdb1/build/temp.linux-x86_64-2.7/_mysql.c.init_mysql-refcount-errors.v2.html

In particular:

 * saved some vertical space and (imo) made it more readable by combining the two old top bars
 * made top-level errors more prominent by giving them their own full-width line.
 * fixed FOUC issues
 * abandoned prefixfree in favor of pre-processing with autoprefixer
 * reworked flow bullets to not wiggle in webkit on mouseover