The post didn't come through above but going off of info in the post we do not have that picture marker symbol shapes in the new Map Viewer.
We do have a marker based symbol for shapes where you can define the color for the symbols, outline colors, change the size without making the symbol blurry. You can also use effects to add a similar drop shadow but also control the direction, size and color of the shadow.
Just saved the web map with the symbols you want and you will see a url in the web map JSON for the esri symbol and it will be a png you can download.
You can use ago-assistant to find the url or chrome web dev tools.