Use head elements and new manganis syntax in examples (#2688)

* use head elements and new manganis syntax in examples
* only enable desktop workspace example scraping during a dioxus release

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Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

examples/assets/overlay.css

@@ -0,0 +1,13 @@
+html, body {
+    height: 100px;
+    margin: 0;
+    overscroll-behavior-y: none;
+    overscroll-behavior-x: none;
+    overflow: hidden;
+}
+#main, #bodywrap {
+    height: 100%;
+    margin: 0;
+    overscroll-behavior-x: none;
+    overscroll-behavior-y: none;
+}

examples/assets/read_size.css

@@ -0,0 +1,9 @@
+html, body {
+    height: 100%;
+    width: 100%;
+    margin: 0;
+}
+#main {
+    height: 100%;
+    width: 100%;
+}