I'm working on a legacy application created with HTML 4, The application is working correctly on Internet Explorer, I want to run the application on Edge chromium and chrome, but I get many style problems. There is some css styles, but to align elements we use tables and HTML attributes like align.
I tried to check if the HTML and CSS are valid using google chrome extension called Validity but I get those errors
the "align" attribute on the "td" element is obsolete. use css instead
the "bgcolor" attribute on the "td" element is obsolete. use css instead
the "width" attribute on the "table" element is obsolete. use css instead
but those attributes are working correctly with HTML 4 in the application, so why those errors ? Is there any tools to check if all the HTML 4 attributes and css are valid/correct or not ?
They are marked as errors and obsolete because they are obsolete and have been for many years.
That they still work is because browsers tend not to break the web and support such things for many years afterwards. However, one should not rely on this as support can disappear at any time without notice.
The way you check for such things is to use the W3C tools that have been around for decades:
W3C HTML Validator
W3C CSS Validator