How to make your own app theme in Barside, step by step

If the 25 built-in looks are close but not quite right, you can make your own app theme in Barside in a few minutes, with no code. Open Settings & backups, find Look & feel and choose Create a theme. The theme builder opens beside the app, and the whole window wears your draft while you change it. Start from a built-in theme, a blank one, one color, a picture or a few words for your AI. Then change 14 colors, the font, the corners and the background. The builder checks contrast as you go, and Fix contrast repairs text that is hard to read.

The theme builder arrived in Barside 1.40. This guide walks through every part of it, from the first click to sharing a finished theme as a file. For the ready-made looks, see all 25 desktop app themes.

How to make your own app theme in 8 steps

1. Open Settings & backups from Barside's sidebar, or type settings in the search bar.
2. Under Look & feel, in Appearance, choose Create a theme. The builder opens on its Start tab with a copy of the theme you are using; a copy of a built-in theme is named "My" plus that theme's name.
3. Type a name in the field at the top, up to 60 characters.
4. On Start, pick a starting point, or choose Surprise me.
5. On Colors, click any swatch to change it.
6. On Type & shape, choose the font, the text size, the corners and a style.
7. On Effects, choose a solid, gradient or moving background, glass panels and shadows.
8. Look at the status at the bottom of the builder. When it says Easy to read, choose Save theme or press Ctrl+S. If it counts contrast issues, click it, and the Contrast tab opens with Fix contrast.

Barside says "Saved “Harbor”. Barside is using it now." and every open window switches to your theme. Cancel, the X or Escape puts your saved theme back instead. If you changed something, Escape first asks "Discard your changes?", with Keep editing and Discard.

Start: pick a starting point

The Start tab offers five starting points. Each one replaces the draft, and everything stays editable afterward.

• A Barside theme. Any of the 25 built-in themes, as it is. Choose a family, then a theme, and the builder copies its colors, font, shape and background.
• A blank theme. Blank dark or Blank light: plain surfaces, ready for your colors. The font you picked stays.
• One color. Pick Your color, and Barside builds a whole palette around it. Choose a Harmony (One hue, Neighbors, Opposite, Three-way or Split), Light or dark, and how much Color in backgrounds you want, from 0 to 100%. Each change redraws the palette.
• A picture. Choose a picture… opens a PNG, JPEG, WebP, GIF or BMP file of up to 40 MB, such as a photo or your wallpaper. Barside finds its main colors and builds the palette from them. Click one of the picture's colors to make it the accent, and set Light or dark to Like the picture, Dark or Light.
• Describe it. Type up to 300 characters, like "A calm forest at dawn, with soft greens and warm light", and choose Create. The AI you connected in Settings → AI designs the theme, and Stop cancels the request. Its answer is checked like an imported file, so anything that is not a valid theme is refused. If no AI is connected, the option says so; the AI assistant guide explains how to connect Claude, ChatGPT, Gemini or OpenRouter.

Surprise me makes a random theme from a random hue, harmony and style, then fixes its contrast so it stays readable. Your font and text size stay as they are. The dice button at the top of the builder does the same from any tab, so you can press it a few times and keep the one you like.

Colors: 14 colors with plain names

The Colors tab lists every color of the theme, in five groups:

Each color has a swatch that opens a picker: a square for saturation and brightness (the arrow keys move it too), a hue bar, and the colors already in your theme. Hover tint and Shadow are the only see-through colors, so they also get an opacity bar. Beside each swatch, a hex field takes #rgb, #rrggbb or #rrggbbaa, with or without the #. On Windows, a pipette button picks any color on your screen; Linux has no screen color picker, so the button does not show there, and Barside for Mac has it.

Text colors show their lowest contrast right next to them, so you see a problem the moment you make one. Two buttons sit at the top of the tab: Light twin (or Dark twin) and Fix contrast.

Type & shape, and effects

Type & shape sets how the app reads and feels:

• Font. Inter (Barside's own), Noto Sans and Ubuntu Sans (both included), your System font, Segoe UI on Windows, a Serif or a Monospace. Fonts on this computer lists the fonts installed on your computer, with a search box, when your system lets Barside read the list.
• Text size, from 90% to 115%. Letters grow or shrink, and windows, boxes and menus keep their size.
• Shape. Corners for Buttons and fields (0 to 20 px) and for Panels and cards (0 to 28 px), with a small preview of both.
• Style. Borrow the title bars, buttons and borders of a built-in family: Barside, Windows, iOS, Ubuntu, KDE, Glass, Gradient or Fluid. A short note under it says what each one changes.

Effects sets what sits behind everything:

• Background. Solid, Gradient or Moving. A gradient takes two or three colors (Add a color, Remove color 3) and an Angle. A moving background takes four colors, a Motion (Drift, Breathe, Sway, Turn, Circle or Rise), a Speed from 25% to 200% and a Color strength. A new moving background starts as strong as text stays readable over it. Switching back to solid keeps your gradient and moving settings for later.
• Glass. Glass panels let the background show through, with Transparency and Blur (0 to 40 px). Glass turns on by itself when you move from a solid background to a gradient or moving one, and you can turn it off.
• Shadows. Shadow strength, from 0 to 100%.

Contrast checks and Fix contrast

The Contrast tab measures every text color against what sits behind it, using WCAG AA, which asks for a contrast of at least 4.5:1 between text and its background:

• Text, Secondary text, Hints and Accent text on each of the five backgrounds.
• Button text on the accent.
• With a gradient or moving background, text and secondary text on each gradient color, and on each moving color at its brightest.

Each pair shows a sample with its ratio, and each check says Passes or Needs 4.5:1. Ratios are rounded down, so 4.49 shows as 4.4 and never passes by rounding. Glass panels are measured as solid colors. The Contrast tab carries a number when pairs fail, and the status at the bottom of the builder counts them from every tab.

Fix contrast repairs them with as few changes as it can. It first softens a moving background, then tries changing one color, then two, and so on, and picks the fix that looks closest to your draft. Each changed color keeps its hue and gets only as much lighter or darker as it needs. Barside says what it did, like "Changed one color: secondary text.", and Undo the fix takes it back.

Undo, redo and Peek at the app

• Undo and Redo are the arrows at the top of the builder, or Ctrl+Z and Ctrl+Shift+Z (or Ctrl+Y) outside text fields. A drag or a burst of typing counts as one step.
• Peek at the app, the eye button, slides the builder away so you can see the whole window in your draft. Back to the builder brings it back, and so does Escape.
• More, the three dots, holds Make a light twin (or Make a dark twin), Start over and Export theme file….
• The builder stays readable whatever you do to the draft. If your text and surfaces get too close, its own panel falls back to black or white text, while the app behind it still shows your colors.

The builder works with the keyboard alone: Tab, the arrow keys in the tabs, choices, sliders and the color square, Enter and Escape. In a narrow docked window, it takes the whole width below the title bar.

Save, rename, duplicate and make a twin

Your themes come first in the gallery, under My themes. Each card has a pencil (Edit) and a More menu:

You can keep up to 50 themes. If a name is taken, Barside adds a number, such as "Harbor 2". A twin gets "Light" or "Dark" after its name. If you delete the theme you are using, Barside switches to Default or Light, whichever matches it.

Export and import a theme file

To share a theme, or to move it to another computer:

1. In My themes, open a theme's More menu and choose Export…. In the builder, More → Export theme file… exports the draft.
2. Pick a place to save it. Barside suggests your Documents folder and a file named after the theme, like Harbor.barside-theme.
3. On the other computer, open Look & feel and choose Import (or Import a theme while My themes is empty), then pick the file.

Barside checks every file before it adds it. It keeps only known fields, accepts only real hex colors, keeps every number within its limits, and never lets a theme carry code or styles of its own. A damaged file is refused with "This file is not a Barside theme. It may be damaged.", and a theme from a newer version with "This theme was made with a newer Barside. Update Barside, then import it again." An imported theme lands in My themes, and Barside says "Imported “Harbor”. Click it to use it."

Where your themes show up

A saved theme reaches every Barside window: the main window, notes pinned to the desktop, the desktop bar, the search bar, Spaces, the Passwords window, clipboard history and meetings. While you edit, only the window with the builder shows the draft; the others switch when you save, and they follow later edits too.

The search bar knows your themes as well. Press Alt+Shift+Space in any app, type a theme's name and choose Theme: Harbor. Your themes are listed before the built-in ones, and Barside says "Theme changed."

Your themes are settings of each computer. They travel in ZIP backups and cloud backups and come back with a restore, but cloud sync keeps settings separate, so they do not sync; Export… and Import move them. Read how to sync notes between computers and local-first storage and private backups for the details.

Motion, readability and your system

• Less motion. A moving background in your own theme stands still when your computer asks for less motion, and the Effects tab says so. Since 1.40, the built-in Fluid themes stop at once too. On Windows 11, turn off Animation effects in Settings → Accessibility → Visual effects; on Linux, the setting's name depends on your desktop.
• Readable by default. Palettes made from one color or a picture, and every Surprise me theme, are built to pass the contrast checks. A theme started from a built-in Fluid theme can show contrast issues for secondary text over its moving colors, and Fix contrast softens them.
• Windows, Linux and Mac. The builder is the same in Barside for Windows, for Linux and for Mac. The differences are small: Segoe UI is offered on Windows, the screen color picker is on Windows only, and the list of installed fonts appears only where the system allows it.

Privacy

Themes are local. A theme you build is sent nowhere, with one exception that you choose: Describe it sends your sentence to the AI company you connected, only when you choose Create, and that company's data policy applies. A picture you start from is read on your computer, shrunk and never uploaded or kept. The list of your fonts is read on your computer, and only when you ask for it. See the AI you connect and your data.

Works well with