Have a look at this post, this is your problem and its the apps that use gtk font sizes under kde, i.e. firefox, gimp etc
http://www.knoppix.net/forum/viewtop...light=gtk+font
First of all, I am using the Knoppix 5.0.1 live DVD at work when I work on the company's website, due to the software I primarily use (GIMP, Inkscape, etc.) not running reliably on my Windows 98 box. I have noticed that certain apps under KDE control the size of their fonts based on the monitor's DPI as reported by the X server. Unfortunately, if the DPI is not set correctly, this can lead to fonts being too large or too small. In my case, they're too small--almost unreadable. The application in my case is Mozilla Firefox. I have tried the many suggestions I have found all over the web for manually setting the monitor's DPI, but to no avail. It seems as though all of my manual configuration attempts are ignored by KDE, and my settings are stuck at 75 DPI, whereas my monitor should be at 96 DPI. I have tried:
- added DisplaySize xxx xxx to xorg.conf under the Monitor section
added Option "UseEdidDpi" "False" under the Device section
added ServerArgsLocal=-dpi 96 -nolisten tcp to /etc/kde3/kdm/kdmrc
I found the following web page particularly informative during my attempted customizations: http://www.mozilla.org/unix/dpi.html
Does anybody know how this can be done? The small fonts drive me nuts! I would rather not force Mozilla font sizes with .css files as some have done, since I don't believe that is the solution to the real problem, only a coverup. I have also read that some people with NVIDIA graphics cards have solved the problem by switching from the open source nv driver to NVIDIA's driver, but I don't see how this would be possible running from the live DVD. Since Gnome defaults to 96 DPI, I am currently running Knoppix with that desktop mode. In Gnome, the fonts are just the right size, but things aren't set up very well compared to the KDE profile (as is to be expected since Knoppix was designed to be run under KDE).
Thanks for your time,
-~Chris
Have a look at this post, this is your problem and its the apps that use gtk font sizes under kde, i.e. firefox, gimp etc
http://www.knoppix.net/forum/viewtop...light=gtk+font
Thanks for the helpful info Hal8000,
It seems the problem has been resolved in the 5.1.1 version of Knoppix (I had been using 5.0.1).

LENOVO THINKPAD T14s GEN 2a Ryzen 7 PRO 5850U 1.9GHz 16GB 256GB TOUCH - NO OS
$299.95
Lenovo ThinkPad L14 Gen 3 Laptop 14” FHD Core i5 12th 16GB RAM 512GB SSD Win 11
$374.99
Lenovo ThinkPad L15 Gen 3 15.6" 16GB, Thunder Black
$242.00
Lenovo Thinkpad E15 15.6" Laptop i5/i3 8GB RAM Up to 1TB SSD HDD Tested Working
$136.55
Lenovo ThinkPad T460 Intel Core i5-6300U @ 2.40 GHz 8GB 128GB SSD Windows 10 Pro
$89.95
Lenovo Thinkpad T14 Gen 2i 14" 16GB 512GB, Black
$313.00
Lenovo LOQ 15 15.6" FHD 144Hz 8-Core i5-12450HX 16GB 512GB SSD GeForce RTX 4050
$760.00
Lenovo Legion 5 Gaming 15.1" WQXGA OLED 165Hz Core i9-14900HX 16GB 1TB RTX 5070
$1439.00
Lenovo Thinkpad T14 Gen 2 14" 32GB, Thunder Black
$287.95
Lenovo ThinkPad T580 15.6" FHD W11 Pro Laptop i5-8250U 8GB 256GB Backlit / USB C
$175.00