To redirect the url - php

Question

in the below code i am searching a data before searching my url will be in coursemaster_site and when i search it will be in coursemaster_site/index1 and when i close the search results the url will be in coursemaster_site /coursemaster_site but i want url to be in coursemaster_site after closing the search results.
controller:coursemaster_site
function index1()
{
$data = array();
$keyword = $this->input->post('keyword');
if($keyword!=""){
$data['results'] = $this->coursemaster_model->search($keyword);
}
$this->load->view('coursemaster_view', $data);
}
view:coursemaster_view
<form action="<?php echo site_url('coursemaster_site/index1');?>" method = "post">
<br/><center>SEARCH:<input type="text" name = "keyword" required/>
<input type="submit" name="submit" id="opn" value = "Search" onClick="hide1('hiddendiv')" class="btn-success btn" /></center>
</form>
<?php
if (isset($_POST['submit'])) { // Here
// Do the search here
if($results){
?> <div id='hideme'>
CLOSE<a href='coursemaster_site' class='close_notification' title='Click to Close'>
<img src="<?php echo base_url('img/close.png'); ?>" width="15" height="15" alt="Close" onClick="hide('hideme')"/>
</a><div style="background:#FFFFFF; width:1000px; height: 540px; position: absolute; left: 20%; top: 35%; margin-left: -100px; margin-top: -120px" id="modal" >
<table class="display2 table table-bordered table-striped" id='results'>
<tr>
<th>course_code</th>
<th>course name</th>
</tr>
<tr><?php
foreach ($results as $row) {
?>
<td><?php echo $row->course_code;?></td>
<td><?php echo $row->course_name;?></td>
</tr>
<?php
}
}else{
echo"<div id='hideme'>
CLOSE<a href='coursemaster_site' class='close_notification' title='Click to Close'>";
echo "<div id='modal' style='background:#FFFFFF; width:1000px; height: 525px; position: absolute; left: 20%; top: 35%; margin-left: -100px; margin-top: -110px'>";
}
echo"no results";
echo'</div>';
echo '</div>'; }
// If closing
?>
</table>
</div></div>
<script>
$('a.modal').bind('click', function(event) {
event.preventDefault();
$('#modal').fadeIn(10);
});
function hide(obj) {
var el = document.getElementById(obj);
el.style.display = 'none';
}
function hide1(obj) {
var el = document.getElementById(obj);
el.style.display = 'none';
}
</script>

Answer 1

Change to:
<div id='hideme'>CLOSE
<a href='/coursemaster_site' class='close_notification' title='Click to Close'>
...
on both places. The leading slash makes the href start from root.

Answer 2

Do the following changes and check if it works or not:
<div id='hideme'>
CLOSE<a href='javascript:void(0);' class='close_notification' title='Click to Close'>";