If it’s only required to work in WebKit based browsers, and CSS is allowed in ‘purely through HTML5’, you could try:
input[type=number] {
-webkit-text-security: disc;
}
I’m not sure if there’s currently any equivalent for other browsers, in the future this may be controllable through the . The CSS3 version of appearance
CSS propertyappearance
has been dropped from the spec, so it looks like you’ll have to wait for the standardization of text-security
for a cross browser solution.