How do I hide the field labels and use only placeholders?

I removed field labels and created placeholders as per this article: https://yikesplugins.com/support/knowledge-base/hide-field-labels/

The issue now, that the placeholder does not disappear on the mouseclick, and when user starts typing there a real value, the new value gets mixed with the placeholder.

Is that a normal behaviour? Can it be adjusted, so the placeholder would disappear when user starts entering new value into the field?

Thanks,
Eugene