# ToastViewport
The fixed container that holds all `Toast` notifications. Place exactly one `ToastViewport` in your main layout (e.g. `MainLayout.htmx`). The viewport is invisible when empty and stacks toasts upward as they are added.
---
## HTML structure
```
div[id={id}].toast-viewport.fixed.bottom-4.right-4.z-50.flex.flex-col-reverse.gap-2.w-80.pointer-events-none
```
---
## CSS mechanics
| Class | Effect |
|---|---|
| `fixed bottom-4 right-4` | Anchored to the bottom-right corner of the viewport |
| `z-50` | Floats above all other content including dialogs and dropdowns |
| `flex flex-col-reverse gap-2` | New toasts appear on top; older ones push downward |
| `w-80` | Matches the default toast width |
| `pointer-events-none` | The container itself doesn't capture clicks — toasts set `pointer-events-auto` individually |
---
## Constructor signature
```csharp
public ToastViewport(string id = "toast-viewport")
```
| Parameter | Description |
|---|---|
| `id` | Element id (default: `"toast-viewport"`). `components.js` queries `#toast-viewport` by default — only change this if you also update the JS lookup. |
---
## Usage examples
### Place in MainLayout
```html
$$Body$$
$$ToastViewport$$
```
```csharp
// MainLayout.htmx.cs
public IHtmxComponent ToastViewport { get; } = new ToastViewport();
protected override void RenderToastViewport(HtmxRenderContext ctx)
=> ToastViewport.Render(ctx.Next());
```
### Custom id (advanced)
```csharp
new ToastViewport(id: "notifications-container")
```
Then update the JS lookup:
```js
// In components.js or a custom script:
const viewport = document.getElementById('notifications-container');
```
### Custom position (bottom-left)
The position is set by Tailwind classes on the rendered element. To change position, subclass the component or pass `extraClasses` if supported, or override the `toast-viewport` class in your `input.css`:
```css
.toast-viewport {
bottom: 1rem;
left: 1rem;
right: auto;
}
```
---
## Tips and tricks
- Place `ToastViewport` once in the outermost layout — not inside HTMX swap targets, since HTMX replaces the target's contents and would remove the viewport.
- The default id `"toast-viewport"` is hard-coded in `components.js` for the `showToast` lookup. If you rename it, update the JS too.
- `ToastViewport` renders as an empty `div` — it has no visual presence until a toast is appended to it.
- Multiple viewports on the same page are valid for different toast regions (e.g. top-right and bottom-right), but `showToast` will target whichever viewport id it is configured for.
- Multiple viewports on the same page are valid for different toast regions (e.g. top-right and bottom-right), but `showToast` will target whichever viewport id it is configured for.
---
## Complete page example
`ToastViewport` is a layout-level concern — it lives in `MainLayout`, not in individual page templates. The example below shows the full integration pattern.
**`Templates/MainLayout.htmx`** (excerpt)
```html
$$NavBar$$
$$Content$$
$$ToastViewport$$
$$Scripts$$
```
**`Templates/MainLayout.htmx.cs`** (excerpt)
```csharp
namespace Htmx.ApiDemo.Templates;
public sealed class MainLayout : MainLayoutBase
{
private readonly IHtmxComponent _nav;
private readonly IHtmxComponent _content;
private readonly IHtmxComponent _viewport;
public MainLayout(IHtmxComponent content, IHtmxComponent nav)
{
_nav = nav;
_content = content;
// Place one viewport at bottom-right for all pages
_viewport = new Components.ToastViewport(
id: "toast-viewport",
position: "bottom-right");
}
protected override void RenderNavBar(HtmxRenderContext ctx) => _nav.Render(ctx.Next());
protected override void RenderContent(HtmxRenderContext ctx) => _content.Render(ctx.Next());
protected override void RenderToastViewport(HtmxRenderContext ctx) => _viewport.Render(ctx.Next());
}
```
**Triggering a toast from any handler**
```csharp
// Any POST handler can fire a toast without changing the ToastViewport markup.
ctx.Response.Headers["HX-Trigger"] =
"""{"showToast":{"title":"Saved!","description":"Your changes have been persisted."}}""";
```
**Two-viewport layout** (top-right errors + bottom-right successes)
```csharp
_errorViewport = new Components.ToastViewport(id: "error-viewport", position: "top-right");
_successViewport = new Components.ToastViewport(id: "success-viewport", position: "bottom-right");
// Error toast
ctx.Response.Headers["HX-Trigger"] =
"""{"showToast":{"viewportId":"error-viewport","title":"Something went wrong."}}""";
```