The font of the s.s. is defined as 1em, so the result varies from theme to theme. If you had the Custom Design upgrade, you could change this once for all. Without the upgrade you can only change it for each separate s.s.:
Ugly horizontal bar has appeared in almost all codes. using the div tags is a solution, and I already use it to introduce vertical scroll bars, at this moment it will be really inconvenient to add those divs to every code to decrease font.