I’ve submitted 404 error theme below are live preview.
It’s rejected, reason below
Your template’s design does not meet our approval standards and will need to be significantly improved before being reviewed again. I’m not able to list specific areas or aspects your template needs to be improved in (in terms of design). Some aspects of a template design include typography, graphics, spacing and layout. I recommend you begin by evaluating these areas and making improvements as necessary.
Could anyone please advice more in specified ideas which can improve?
I think it’s too basic.
Ask yourself this question: “Will I buy this?” Do just try to get approved, if you want the template to sell well – try to be as uniqe as possiable.
Try adding a little spice to it it look very naked. almost as if you didn’t care about styling even the little site-map link on the bottom.
I agree with Bluz, 404 pages usually contain few texts so every detail has a real importance. For example, have a look at the spacing : your search field is not centered and not aligned with anything else, vertical spacing between each part is different, you can use a grid to get a stronger structure (example : the big space at the bottom of the search field).