Support for [fixed-center] moes

public/css/yemi.css

@@ -14,6 +14,12 @@
     padding: 10px;
     border: 1px solid gray;
 }
+[moe][fixed-center] [url]:not([show]) {
+    position: fixed !important;
+    top: 50% !important;
+    left: 50% !important;
+    transform: translate(-50%, -50%) !important;
+}
 [moe] [url][right] {
     right: 0;
     min-width: 200px;