diff --git a/clients/linux/src/app.rs b/clients/linux/src/app.rs
index fe4315cd..33ebc540 100644
--- a/clients/linux/src/app.rs
+++ b/clients/linux/src/app.rs
@@ -23,6 +23,10 @@ pub const APP_ID: &str = "io.unom.Punktfunk";
 /// named palette so dark mode just works.
 const CSS: &str = "
 .pf-host-card { padding: 16px; }
+/* The FlowBoxChild draws the hover/selection highlight AROUND the card (it wraps it
+   with its own padding), so its corners must run concentric with the card's 12px —
+   radius = card radius + the child's padding ring. */
+.pf-host-grid > flowboxchild { border-radius: 15px; }
 .pf-pill { font-size: 0.72em; font-weight: bold; padding: 2px 10px; border-radius: 999px;
            color: alpha(currentColor, 0.8); background: alpha(currentColor, 0.1); }
 .pf-pill.pf-green { color: @success_color; background: alpha(@success_color, 0.15); }
diff --git a/clients/linux/src/ui_hosts.rs b/clients/linux/src/ui_hosts.rs
index 0e8ee553..847c5134 100644
--- a/clients/linux/src/ui_hosts.rs
+++ b/clients/linux/src/ui_hosts.rs
@@ -386,7 +386,7 @@ impl SimpleComponent for HostsPage {
         sender: ComponentSender<Self>,
     ) -> ComponentParts<Self> {
         let make_flow = || {
-            gtk::FlowBox::builder()
+            let f = gtk::FlowBox::builder()
                 .selection_mode(gtk::SelectionMode::None)
                 .activate_on_single_click(true)
                 .homogeneous(true)
@@ -394,7 +394,10 @@ impl SimpleComponent for HostsPage {
                 .max_children_per_line(4)
                 .column_spacing(12)
                 .row_spacing(12)
-                .build()
+                .build();
+            // Scopes the concentric hover-highlight radius (see app.rs CSS).
+            f.add_css_class("pf-host-grid");
+            f
         };
         let heading = |text: &str| {
             let l = gtk::Label::new(Some(text));
diff --git a/docs-site/content/docs/hyprland.md b/docs-site/content/docs/hyprland.md
index fa6fcd06..d58c8182 100644
--- a/docs-site/content/docs/hyprland.md
+++ b/docs-site/content/docs/hyprland.md
@@ -50,12 +50,23 @@ For how long the virtual output lives, and extend-vs-exclusive topology, see
 
 ## Requirements
 
-- A running Hyprland session (any recent release; validate on both a ≤ 0.54 and a ≥ 0.55 install).
+- A running Hyprland session (the `hyprctl`/xdph contracts are verified on **0.55.4**; older
+  releases share the same `hyprctl` surface).
 - **xdg-desktop-portal-hyprland (xdph)** installed and running — the host captures through its
   ScreenCast portal, and steers its custom picker. Without it there is no video.
 - The ScreenCast interface routed to xdph — see `scripts/headless/portals.conf` (a `[Hyprland]`
   section pins `org.freedesktop.impl.portal.ScreenCast=hyprland`).
 
+## Troubleshooting: black / no video (headless output at 0×0)
+
+A headless output only gets a framebuffer once the compositor can allocate one. On some GPU/driver
+combinations (notably NVIDIA, and in nested test setups) that GBM/dmabuf allocation fails and the
+output stays `0×0` — you'll see `GBM: Failed to allocate a GBM buffer: bo null` in the Hyprland log
+(cf. [Sunshine #4197](https://github.com/LizardByte/Sunshine/issues/4197)). The host detects this
+and fails the session with a clear error rather than streaming a blank surface. If you hit it,
+capture the Hyprland log (`hyprctl` instance dir → `hyprland.log`) and check your GPU's GBM support;
+running Hyprland as a real session (not nested) is the supported configuration.
+
 ## Permission system
 
 Hyprland's permission system (`ecosystem.enforce_permissions`, 0.49+, **off by default**) can deny