Why is the site flagged as malicious?

Question

Browsers

Good day. Some users began to complain that Chrome notifies them that the site is not safe. (the site is mine, I'm helping a friend)

Swears at a specific file - content

@import url('./lib/jquery.jgrowl.min.css');
.af-message-success { background-color: green !important; }
.af-message-error { background-color: brown !important; }
.af-message-info { background-color: black !important; }
.ajax_form.af_example {
    width: 100%;
}
.ajax_form.af_example .controls input,
.ajax_form.af_example .controls textarea {
    width: 100%;
}
.ajax_form .error {
    color: brown;
}
@media screen and (min-width: 320px) {
    .ajax_form.af_example .controls button[type="submit"] {
        float: right;
    }
}
@media screen and (max-width: 320px) {
    .ajax_form.af_example .controls button {
        width: 100%;
        margin-top: 5px;
    }
}

Actually, the file itself does not visually cause me any kind of concern ...
File address

https://site.com/assets/components/ajaxform/css/default.css

Virustotal report
https://site.com - knocks out that everything is ok

https://site.com/assets/components/ajaxform/css/default.css

- Kaspersky grit knocks out that this link is phishing
Webbrut - that it is malicious ... Tell me

where to dig?