# Preparations
* in IDE:
1. create `/themes/advanced/compress_fixture.css` file with this content:
```
lang=css
@media screen and (min-width: 480px) and (max-width: 639px) {
body {
background-color: red;
}
}
@media screen and (max-width: 640px) {
body {
background-color: green;
}
}
```
2. create `/themes/advanced/compress_fixture.tpl` file with this content:
```
lang=html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<link rel="stylesheet" rev="stylesheet" href="<inp2:m_Compress files='compress_fixture.css'/>" type="text/css" />
</head>
<body>
</body>
</html>
```
3. in `/system/config.php` change `CompressionEngine` setting value to `yui`
* in Admin Console:
# go to {nav Configuration > Website > Themes} section
# press `Rescan Themes` button on toolbar
# Part 1
NOTE: Test with both Debug Mode enabled and disabled.
* on Front-End:
# open this URL: `.../compress_fixture.html` (replace `...` with base url of your In-Portal installation)
# resize window to be smaller than 640px in width
# confirm, that window background color is green