Themes & Mods
Themes change Gallium's colours, wallpaper and feel. Mods restyle the interface itself. Every file here is checked and virus-scanned before it's listed.
Themes are only colours, a few settings and a picture. Mods are only CSS. Anything that tries to load files from the internet, run code or hide the whole window is rejected.
Every file is scanned with ClamAV whenever it changes and every week with fresh definitions. When you install it, Gallium scans it again with Microsoft Defender on your PC.
Gallium shows exactly what a file changes and asks before installing. If a mod ever breaks things, press Ctrl Shift M to turn every mod off.
How to install
Pick whichever way is easiest for you. Every way ends at the same place: Gallium shows what the file does, scans it, and asks before installing.
It switches on straight away, with an Undo button if you change your mind. Swap looks any time from the Customize button in the corner of the home screen, or in Settings › Themes & Mods.
It's on straight away. Turn it on or off, or remove it, in Settings › Themes & Mods. If anything looks wrong, press Ctrl Shift M to switch every mod off at once.
Install the latest Gallium from this site first; its installer teaches Windows to open these files with Gallium. You can also right-click the file, choose Open with, then Gallium. Or just drag the file onto Gallium's window.
Windows says that about many downloaded files. Theme and mod files are plain text that Gallium checks and scans with Microsoft Defender before anything is installed. If Gallium's check or scan fails, it won't install the file.
For a theme, click Undo right after installing, or pick another look from the Customize button or Settings › Appearance. For a mod, switch it off or remove it in Settings › Themes & Mods.
Mods are only CSS, so they can't run code, read your tabs or reach the internet, and Gallium blocks anything that tries. They can still change how Gallium looks, so only install mods from people you trust.
Check a file
Drop it here to see what it does before you install it. Nothing is uploaded: the check runs in your browser.
Make your own
The Theme Studio in Gallium shows every change live on the real browser.
On the home screen, click the Customize button in the corner, then Theme Studio. Or go to Settings, Themes & Mods.
Style, light or dark, two colours, an accent, font, corner roundness and a wallpaper, even your own photo.
Save it, then Export to get a .gtheme file. Anyone with Gallium can install it by opening or dragging it in.
{
"gallium": 1,
"type": "theme",
"name": "Ocean",
"author": "You",
"style": "glass",
"dark": false,
"colors": { "c1": "#dbe8ff", "c2": "#c9dcff", "accent": "#3f7cf2" },
"settings": { "font": "apple", "radius": 1.2 },
"wallpaper": "tide"
}{
"gallium": 1,
"type": "mod",
"name": "Big Clock",
"author": "You",
"description": "A larger clock on the home screen.",
"css": "#clock { font-size: 160px !important }"
}The rules. Colours are written like #a1b2c3. Styles are gradient, apple or glass. The wallpaper is a built-in name or an embedded JPEG, PNG or WebP picture up to 5 MB. Mods are CSS up to 100 KB, with no @import, no outside url(), nothing that hides the whole window. To get yours listed here, upload it; it's checked and scanned automatically.
Upload
Every upload is format-checked and virus-scanned before anyone can download it. Files that pass are reviewed, then added to the gallery for everyone.
It's checked right here in your browser first, so you know straight away if something's wrong.
Click Upload and submit the form on GitHub (a free account). A robot scans it with ClamAV and posts the result within about 2 minutes.
Once a clean file is approved, it appears in the gallery with its scan results, ready for anyone to install.
Now double-click it in your Downloads, or drag it onto Gallium. Using Gallium? The install sheet opens by itself. Need help?