Style - Add watermark class

Author: graphieros

src/vue-data-ui.css

@@ -21,4 +21,12 @@
 
 .vue-data-ui-zoom-minus {
     cursor: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20' height='24' width='24'><path fill='none' d='M 14.65 14.65 L 18 18' stroke-linejoin='round' stroke-width='2' stroke='white'/><path fill='none' stroke-width='1' stroke='black' d='M 9 1 A 1 1 0 0 0 9 17 A 1 1 0 0 0 9 1 M 14.65 14.65 L 18 18 M 5 9 L 13 9'/><path fill='none' d='M 9 0 A 1 1 0 0 0 9 18 A 1 1 0 0 0 9 0' stroke-width='0.5' stroke='white'/><path fill='none' d='M 4 8 L 14 8 L 14 10 L 4 10 Z' stroke-linejoin='round' stroke-width='0.5' stroke='white'/></svg>") 10 10, pointer;
+}
+
+.vue-data-ui-watermark {
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+    pointer-events: none;
 }