updated hover-on to display tooltips with css rather than js

It's sooo much better this way

src/content/hover.css

@@ -0,0 +1,115 @@
+[data-tooltip] {
+    display: inline-block;
+    position: relative;
+}
+
+/* Tooltip styling */
+[data-tooltip]:before {
+    content: attr(data-tooltip);
+    display: none;
+    position: absolute;
+    background: #000;
+    color: #fff;
+    padding: 4px 8px;
+    font-size: 14px;
+    line-height: 1.4;
+    min-width: 100px;
+    text-align: center;
+    border-radius: 4px;
+}
+
+/* Dynamic horizontal centering */
+[data-tooltip-position="top"]:before,
+[data-tooltip-position="bottom"]:before {
+    left: 50%;
+    -ms-transform: translateX(-50%);
+    -moz-transform: translateX(-50%);
+    -webkit-transform: translateX(-50%);
+    transform: translateX(-50%);
+}
+
+/* Dynamic vertical centering */
+[data-tooltip-position="right"]:before,
+[data-tooltip-position="left"]:before {
+    top: 50%;
+    -ms-transform: translateY(-50%);
+    -moz-transform: translateY(-50%);
+    -webkit-transform: translateY(-50%);
+    transform: translateY(-50%);
+}
+
+[data-tooltip-position="top"]:before {
+    bottom: 100%;
+    margin-bottom: 6px;
+}
+
+[data-tooltip-position="right"]:before {
+    left: 100%;
+    margin-left: 6px;
+}
+
+[data-tooltip-position="bottom"]:before {
+    top: 100%;
+    margin-top: 6px;
+}
+
+[data-tooltip-position="left"]:before {
+    right: 100%;
+    margin-right: 6px;
+}
+
+/* Tooltip arrow styling/placement */
+[data-tooltip]:after {
+    content: '';
+    display: none;
+    position: absolute;
+    width: 0;
+    height: 0;
+    border-color: transparent;
+    border-style: solid;
+}
+
+/* Dynamic horizontal centering for the tooltip */
+[data-tooltip-position="top"]:after,
+[data-tooltip-position="bottom"]:after {
+    left: 50%;
+    margin-left: -6px;
+}
+
+/* Dynamic vertical centering for the tooltip */
+[data-tooltip-position="right"]:after,
+[data-tooltip-position="left"]:after {
+    top: 50%;
+    margin-top: -6px;
+}
+
+[data-tooltip-position="top"]:after {
+    bottom: 100%;
+    border-width: 6px 6px 0;
+    border-top-color: #000;
+}
+
+[data-tooltip-position="right"]:after {
+    left: 100%;
+    border-width: 6px 6px 6px 0;
+    border-right-color: #000;
+}
+
+[data-tooltip-position="bottom"]:after {
+    top: 100%;
+    border-width: 0 6px 6px;
+    border-bottom-color: #000;
+}
+
+[data-tooltip-position="left"]:after {
+    right: 100%;
+    border-width: 6px 0 6px 6px;
+    border-left-color: #000;
+}
+
+/* Show the tooltip when hovering */
+[data-tooltip]:hover:before,
+[data-tooltip]:hover:after {
+    display: block;
+    z-index: 50;
+}

src/manifest.json

@@ -41,7 +41,8 @@
         "content/hover.js",
         "background/storage.js",
         "content/content.js"
-      ]
+      ],
+      "css": ["content/hover.css"]
     }
   ],
   "permissions": [