style: emphasize update download cancellation

Render the active download cancellation action with a red background and black text, retaining the danger styling while cancellation is pending.

renderer/app.js

@@ -7690,6 +7690,7 @@ function _setUpdateDialogBusy(busy, cancelable = false) {
   if (installButton) installButton.disabled = busy;
   if (closeButton) closeButton.disabled = busy;
   if (dismissButton) {
+    dismissButton.classList.toggle('update-cancel-button', Boolean(busy && cancelable));
     dismissButton.disabled = Boolean(busy && (!cancelable || _updateCancelBusy));
     dismissButton.textContent = busy && cancelable
       ? (_updateCancelBusy ? 'Abbrechen…' : 'Download abbrechen')

renderer/styles.css

@@ -2484,6 +2484,18 @@ select.hs-input { max-width: none; width: auto; min-width: 140px; }
   text-align: right;
 }
 
+#dismissUpdateBtn.update-cancel-button {
+  border-color: transparent;
+  background: var(--danger);
+  color: #000;
+}
+
+#dismissUpdateBtn.update-cancel-button:hover {
+  border-color: transparent;
+  background: color-mix(in srgb, var(--danger) 82%, #fff);
+  color: #000;
+}
+
 .update-dialog-actions {
   grid-column: 1 / -1;
   display: flex;

tests/ui-smoke.js

@@ -2470,6 +2470,7 @@ setTimeout(async () => {
         closeDisabled: document.getElementById('updateCloseBtn').disabled,
         dismissDisabled: document.getElementById('dismissUpdateBtn').disabled,
         dismissText: document.getElementById('dismissUpdateBtn').textContent,
+        dismissDanger: document.getElementById('dismissUpdateBtn').classList.contains('update-cancel-button'),
         headerHidden: header.hidden,
         messageHidden: document.getElementById('updateMessage').hidden,
         messageText: document.getElementById('updateMessage').textContent,
@@ -2477,7 +2478,7 @@ setTimeout(async () => {
         progressText: progress.getAttribute('aria-valuetext')
       };
     })()\`);
-    check('Busy update keeps its progress dialog open with download cancellation available', busyUpdateState.display === 'flex' && busyUpdateState.hidden === 'false' && busyUpdateState.closeDisabled === true && busyUpdateState.dismissDisabled === false && busyUpdateState.dismissText === 'Download abbrechen' && busyUpdateState.headerHidden === false);
+    check('Busy update keeps its progress dialog open with a dangerous download cancellation action', busyUpdateState.display === 'flex' && busyUpdateState.hidden === 'false' && busyUpdateState.closeDisabled === true && busyUpdateState.dismissDisabled === false && busyUpdateState.dismissText === 'Download abbrechen' && busyUpdateState.dismissDanger === true && busyUpdateState.headerHidden === false);
     check('Update progress exposes an accessible live value', busyUpdateState.progressLabel === 'Update-Fortschritt' && busyUpdateState.progressText === 'Download 50%');
     check('Busy update shows progress only below the bar', busyUpdateState.messageHidden === true && busyUpdateState.messageText === 'Update v9.9.9 verfügbar');