Can't see the send button in HTML contact form - html

Question

I'm trying to make a simple HTML contact form, but when I upload the HTML page to the internet, the send and clear buttons are not showing up - they're invisible.
The funny thing is if I hover the mouse over where they are supposed to be, I can see that there is a button there.
Why could this be?
<form action="contact.php" method="post">
<div>
<label for="contactname">Name</label>
<input type="text" name="contactname" class="textfield" id="contactname" value="" />
<span class="require"> *</span>
<label for="contactsubject">Subject</label>
<input type="text" name="contactsubject" class="textfield" id="contactsubject" value=""/>
<span class="require"> *</span>
<label for="contactemail">Your E-mail</label>
<input type="text" name="contactemail" class="textfield" id="contactemail" value="" />
<span class="require"> *</span>
<label for="contactmessage">Your Message</label>
<textarea name="contactmessage" id="contactmessage" class="textarea" cols="8" rows="12"></textarea>
<span class="require"> *</span>
<input type="submit" value="Send">
<input type="reset" value="Clear">

Answer 1

add / end slash to both send & clear
<input type="submit" value="Send"/>
and
<input type="reset" value="Clear"/>
or you can also do like this:
<input type="submit" value="Send"></input>
<input type="reset" value="Clear"></input>
<input> is starting tag
</input> is ending tag
UPDATE 1: answer for how to use image for submit button
change input type to "image"
<input type="image" value="submit" src="submit1.jpg" alt="submit Button" onMouseOver="this.src='submit1.jpg'">