Custom CSS is the final layer of the styling system. You should always start with Theming for broad changes, and then use CSS for small, specific tweaks that the theme system cannot handle. Good use cases for custom CSS include:Documentation Index
Fetch the complete documentation index at: https://docs.thesys.dev/llms.txt
Use this file to discover all available pages before exploring further.
- Changing the font weight of a specific card’s title.
- Adding a unique border to an element.
- Adjusting the margin on a particular button.
How to Find CSS Classes
The most reliable way to find the correct class name for a C1 element is to use your browser’s developer tools.- In your browser, right-click the element you want to style.
- Select “Inspect” from the context menu.
- The developer tools panel will open, highlighting the element’s HTML. The
classattribute will contain the class names you can use as CSS selectors.
Applying Your Custom CSS
Let’s say we want to make the title of all C1-generated cards uppercase. You can add your override rules in a CSS file.Best Practices
- Be Specific, But Not Too Specific: Avoid overly complex selectors like
div > span > p.c1-title. These are very likely to break with SDK updates. Prefer targeting a single, stable-looking class like.c1-card-title.