LilyDesignSystem.Blazor.Headless 0.6.0

Lily Design System™ - Blazor Headless

A comprehensive headless Blazor component library with accessible, unstyled Razor components for building design systems. Every component follows WCAG 2.2 AAA guidelines with full ARIA support, keyboard navigation, and internationalization readiness.

Headless means zero CSS, zero styles, zero opinions about appearance. You provide all styling. Components provide structure, semantics, accessibility, and behavior.

Features

• Headless Blazor Razor components
• .NET 10 with C#
• WCAG 2.2 AAA accessibility compliance
• Full keyboard navigation support
• ARIA attributes and roles
• Internationalization-ready (no hardcoded strings)
• Zero dependencies beyond Blazor
• Works with any CSS framework or custom styles

Quick Start

Install

Add a ProjectReference to the library:

<ProjectReference Include="../lily-design-system-blazor-headless/src/LilyBlazorHeadless/LilyBlazorHeadless.csproj" />

Basic Usage

@using LilyBlazorHeadless.Components

<Form Label="Contact" OnSubmit="HandleSubmit">
    <Field Label="Name" Required="true" Error="@GetError("name")">
        <TextInput Label="Name" Value="@name" ValueChanged="v => name = v" Required="true" />
    </Field>
    <Button Type="submit">Submit</Button>
</Form>

Commands

Project Structure

lily-design-system-blazor-headless/
├── AGENTS.md
├── CLAUDE.md
├── README.md -> index.md
├── index.md
├── spec/index.md
├── AGENTS/
│   ├── accessibility.md
│   ├── components.md
│   ├── headless.md
│   ├── internationalization.md
│   ├── lily.md
│   └── theme.md
├── src/LilyBlazorHeadless/
│   ├── LilyBlazorHeadless.csproj
│   └── Components/
│       └── {ComponentPascalCase}.razor
└── tests/LilyBlazorHeadless.Tests/
    ├── LilyBlazorHeadless.Tests.csproj
    └── Components/
        └── {ComponentPascalCase}Tests.cs

Architecture

Component Patterns

Each component is a Razor component (.razor file) in Components/:

@namespace LilyBlazorHeadless.Components

<button class="@($"button {CssClass}")" @attributes="AdditionalAttributes">
    @ChildContent
</button>

@code {
    [Parameter] public string CssClass { get; set; } = "";
    [Parameter] public RenderFragment? ChildContent { get; set; }
    [Parameter(CaptureUnmatchedValues = true)]
    public Dictionary<string, object>? AdditionalAttributes { get; set; }
}

Blazor Patterns

Root Element CSS Class

Every component's first HTML element sets a class combining the kebab-case name with consumer CssClass:

<button class="@($"button {CssClass}")">
<div class="@($"banner {CssClass}")">
<nav class="@($"breadcrumb-nav {CssClass}")">

Headless Principles

• Zero CSS in any component -- fully headless
• Semantic HTML structure
• ARIA attributes for accessibility
• Consumers provide all CSS via CssClass parameter
• Consumers provide all user-facing text via parameters (i18n-ready)
• No inline styles, colors, sizes, spacing, or visual treatment

Testing

Stack

• bUnit -- Blazor component testing library
• xUnit -- test framework
• dotnet test -- test runner

Test File Pattern

using Bunit;
using Xunit;
using LilyBlazorHeadless.Components;

public class ButtonTests : TestContext
{
    [Fact]
    public void Renders_With_Correct_Tag()
    {
        var cut = RenderComponent<Button>(parameters =>
            parameters.AddChildContent("Click me"));
        var button = cut.Find("button");
        Assert.NotNull(button);
        Assert.Contains("Click me", button.TextContent);
    }
}

Related Projects

• Lily Design System - Parent project
• Blazor Web Examples - Blazor styled example app
• React Headless - React equivalent
• Svelte Headless - Svelte equivalent
• Vue Headless - Vue equivalent
• Angular Headless — Angular 20 equivalent

License

MIT or Apache-2.0 or GPL-2.0 or GPL-3.0, or contact us for more options.

Contact

Joel Parker Henderson (joel@joelparkerhenderson.com)

Lily™ and Lily Design System™ are trademarks.