<div class="demo-main-container">
<div class="demo-form-container"> 
<form action="" method="post"> 
<div class="select-block">
<select name="list_of_activities" class="form-select">
<option value="" disabled selected> </option>
<option value="swimming" <?php echo ($_POST['list_of_activities']=='swimming'?'selected':'')?>>Swimming</option>
<option value="football" <?php echo ($_POST['list_of_activities']=='football'?'selected':'')?>>Football </option>
<option value="yoga" <?php echo ($_POST['list_of_activities']=='yoga'?'selected':'')?>>Yoga</option>
<option value="golf" <?php echo ($_POST['list_of_activities']=='golf'?'selected':'')?>>Golf</option>
<option value="tennis" <?php echo ($_POST['list_of_activities']=='tennis'?'selected':'')?>>Tennis</option>
</select>
</div>
<div class="container" style="margin-top: 20px;">
<div class="row justify-content-between">
<div class="col-md-8">
<?php
if(isset($_POST['submit'])){
if(!empty($_POST['list_of_activities'])) {
$activity_selected = $_POST['list_of_activities'];
echo 'You have selected: <strong>' . $activity_selected . '</strong>';
} else {
echo 'Please select an activity';
}
}
?>
</div>
<div class="col-md-4" style="text-align: right">
<input type="submit" name="submit" value="Submit" class="btn btn-secondary button-submit">
</div>
</div>
</div> 
</form> 
</div>
</div>