I've tried different stuff now to remove the background color now, but the solution seemed to be to change the name of the field allthough I have no idea why this solved my problem. All fields had unique names before this workaround, so this doesn't explain the problem.
Let me know if anybody know why this happens:
Code that turn fields yellow:
<div align="right"><span class="apptxt"><?php echo $navn[$lang]; ?></span> </div>
<td><input name="sambofirstname" type="text" class="formstyle" id="sambofirstname" size="30"
<?php if(isset($_POST['sambofirstname']) && $_POST['sambofirstname'] != ""){ echo "value='".$_POST['sambofirstname']."'"; }?>>
</td>
<div align="right"><span class="apptxt"><?php echo $etternavntxt[$lang]; ?></span></div>
<td><input name="sambosurname" type="text" class="formstyle" id="sambosurname" size="30"
<?php if(isset($_POST['sambosurname']) && $_POST['sambosurname'] != ""){ echo "value='".$_POST['sambosurname']."'"; }?>>
</td>
Code that didn't turn fields yellow:
<div align="right"><span class="apptxt"><?php echo $navn[$lang]; ?></span> </div>
<td><input name="sambofirst" type="text" class="formstyle" id="sambofirst" size="30"
<?php if(isset($_POST['sambofirst']) && $_POST['sambofirst'] != ""){ echo "value='".$_POST['sambofirst']."'"; }?>>
</td>
<div align="right"><span class="apptxt"><?php echo $etternavntxt[$lang]; ?></span></div>
<td><input name="sambosurname" type="text" class="formstyle" id="sambosurname" size="30"
<?php if(isset($_POST['sambosurname']) && $_POST['sambosurname'] != ""){ echo "value='".$_POST['sambosurname']."'"; }?>>
</td>
Another thing, both fields had yellow background with the first example of code, none of them had background color with the second example of code(allthough i didn't change anything with the field name "sambosurname").
This is the corresponding css style if it matters:
<style>
.formstyle{
font-family: Verdana, Geneva, Arial, Helvetica, sans-serif;
font-size: 8pt;
border-right: #CCCCCC 1px solid;
border-top: #CCCCCC 1px solid;
border-bottom: #CCCCCC 1px solid;
border-left: #CCCCCC 1px solid;
color: #000000;
}
</style>