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Themes and Styling

When you create an Anvil app, you’re prompted to choose a theme (such as “Material Design”). Themes contain Form templates, so you have some options to pick from when creating a new Form. For example, the Material Design theme contains Form templates for a page with a navbar and optional sidebar, and a simple blank page.

The Material Design Theme has two pre-defined Form types (plus Custom HTML Forms).

The Material Design Theme has two pre-defined Form types
(plus Custom HTML Forms).

Some themes also define Roles; these are particular styles you can add to components to modify them in ways that fit well with the theme. For example, the Material Design 3 theme defines an Elevated Card role that you can apply to ColumnPanels:

Three Material Design Cards.

Styled components using Roles in the Material Design 3 theme.

Themes consist of:

  • Assets that can be applied to and used in your Forms (HTML templates, CSS files, and images).
  • Roles that you can apply to components.
Learn about customising themes

Customising the theme

The theme is defined by HTML and CSS files that are available in the Assets Editor (under “Assets” in the App Browser).

This is an advanced feature. You don’t need to write HTML and CSS to use Anvil!

You can add, remove and edit theme assets in the Assets Editor. Choose the asset you wish to edit from the drop-down box, and make any necessary changes. You can rename or delete the asset by clicking the buttons in the top-right.

You can edit the HTML and CSS that go into your app.

You can edit the HTML and CSS that go into your app.

The theme is defined by HTML and CSS files that are available under “Assets” in the App Browser.

This is an advanced feature. You don’t need to write HTML and CSS to use Anvil!

You can add, remove and edit theme assets from the App Browser. Choose the asset you wish to edit and a new tab will open in the Editor. You can rename or delete assets by clicking the dots menu next to the asset in the App Browser.

You can edit the HTML and CSS that go into your app.

You can edit the HTML and CSS that go into your app.

Changing the HTML template of a Form

You can change the HTML template of a Form by modifying its html property.

If you set the html property of a Form to the name of an HTML file from Assets, the Form will use it as its template. You do this in a drop-down box in the Properties Panel when the Form is open and no components are selected.

Forms created from the “Blank Panel” template do not have an html property, they are simply ColumnPanels.
Selecting the HTML template of a Form using the Form’s Properties Panel.

Selecting the HTML template of a Form
using the Form’s Properties Panel.

Selecting the HTML template of a Form using the Form’s Properties Panel.

Selecting the HTML template of a Form
using the Form’s Properties Panel.

If you select ‘Custom HTML’, you can write HTML directly into the Form. This is useful if you want to tie the HTML template to this Form rather than making it a global Asset.

Adding your own asset files

You can add your own files to Assets. These could be additional HTML templates, CSS files, JavaScript files or images that you use in your Theme.

To upload or create a file, use ‘Create file’ or ‘Upload file’ in the dropdown box in the Assets Editor.

The Assets Editor with 'Create file' selected from the dropdown, and buttons to create HTML, CSS or JavaScript files.

Creating a new Asset file

The Assets Editor with 'Upload file' selected from the dropdown, and a button to upload files.

Uploading an Asset file

To upload or create a file, click on “Create or upload Asset” under “Assets” in the App Browser. This will bring up a menu for creating and uploading new Assets.

The App Browser with 'Create or upload Asset' circled in red
The menu to create or upload a new Asset

Most assets are lazily loaded when running the app, except for html files and the theme.css file, which are eagerly loaded.

Asset file URL

You can also access Asset files via URL. They are hosted at

<your-app-url>/_/theme/<filename>

For example, if I have an asset named earthrise.jpg in an app published at myapp.anvil.app, my file is hosted at

https://myapp.anvil.app/_/theme/earthrise.jpg

This allows you do things like setting your asset as the source property of an Image component.

Do you still have questions?

Our Community Forum is full of helpful information and Anvil experts.

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