I've got the following css rule:

.icon {
    content: "✓";
    color: #337ab7;
    display: inline-block;
    width: 1em;
    margin-left: -1em;
}

where I use UTF-8 character ✓. But I've found that sometimes this symbol gets replaced with "✓"symbol on a page.

Why it happens?

[Update]:

• Chorme browser of 72.0.3626.121 version.
• Header section contains declaration

[Update 2]: I've found that css file responds with the response header:

content-encoding: br