Why does FF overwrite text on some web pages, esp. in titles or headlines? One line overlaps the next one below it.
Many web pages appear with one line overlapping the one below it--the two lines are not vertically spaced far enough apart to prevent overlap.
ప్రత్యుత్తరాలన్నీ (1)
Reset the page zoom on websites that look wrong: "View > Zoom > Reset" (Ctrl + 0 (zero))
See http://kb.mozillazine.org/Zoom_text_of_web_pages
If you increased the minimum font size then try a lower setting (default is none) as a too high value can cause issues like you described.
Tools > Options > Content : Fonts & Colors: Advanced > Minimum Font Size Tools > Options > Content : Fonts & Colors: Advanced > "Allow pages to choose their own fonts, instead of my selections above"