```
<style type="text/css">
<!--
.style1 {
    color: #666666;
    font-weight: bold;
}
.style8 {font-size: 12px; color: #333333; }
.style9 {
    font-size: 12px;
    font-weight: bold;
    color: #FFFFFF;
}
.style12 {font-size: 12px; font-weight: bold; color: #666666; }
.style13 {font-size: 12px; font-weight: bold; color: #0066FF; }
.style14 {
    color: #0043A8;
    font-size: 16px;
}
.style15 {color: #FFFFFF}
.style16 {color: #990000}
.style18 {color: #990000; font-size: 12px; }
.style20 {font-size: 12px; font-weight: bold; color: #575757; }
-->
</style>

```

above stylesheet is enclosed in `<!-- -->` html comments tag. why? I can't get valid explanation for this; some tutorials do this while some doesn't (like <http://www.w3schools.com/css/css_howto.asp> which I think is very valid reference)
['https://Stackoverflow.com/questions/14749629', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/1684670/']
It is an antiquated method of hiding content from browsers who are older than the standard that introduced `<style>` or `<script>` tags.

There is no valid use for such a habit anymore and in fact will cause more problems than it fixes.

Unless you are developing a website for peolpe living in the 1990's (like the editors at w3schools)... don't do it!
Few browsers consider the `non-HTML` codes as plain text. This comment is used to guide that browser i.e the code is commented so that `browsers` will not display it as html output.