Q. How to cite a website with no author or year?

If there is not an individual author, look for a group, or corporate, author.

For example are citing a web page about Heart Disease from the Centers for Disease Control.  You would use Centers for Disease Control as the author.

Example (in APA):

Centers for Disease Control. (June 23, 2020). Heart disease. https://www.cdc.gov/heartdisease/index.htm