diff --git a/src/styles/gantry.css b/src/styles/gantry.css
index 4da53a6..be218d1 100644
--- a/src/styles/gantry.css
+++ b/src/styles/gantry.css
@@ -579,13 +579,21 @@ html .drive-control-button svg { inline-size: 18px; block-size: 18px; }
 }
 
 /* Tooltips and the settings popover open downward from the beam. */
+/* Tooltips hang from the button's right edge so the last one never leaves
+   the viewport; the label is decorative (the button has its aria-label). */
 html .drive-control-button::after {
-  inset: calc(100% + 0.5rem) auto auto 50%;
-  transform: translate(-50%, -4px);
+  content: attr(data-tooltip) / '';
+  inset: calc(100% + 0.5rem) 0 auto auto;
+  transform: translateY(-4px);
 }
 html .drive-control-button:hover::after,
 html .drive-control-button:focus-visible::after {
-  transform: translate(-50%, 0);
+  transform: none;
+}
+/* An open popover is its own label; touch screens get no hover labels. */
+html .drive-control-button[aria-expanded='true']::after { display: none; }
+@media (hover: none) {
+  html .drive-control-button::after { display: none; }
 }
 html .drive-popover {
   position: absolute;