regex CSS

regex.css

/* if contains "post" */
div[class*="post"] { 
  color: red;
}

/* if begins with "post" */
div[class^="post"] {
  color: red;
}

/* if ends with "post" */
div[class$="post"] {
  color: red;
}

/* if space separated "post" */
div[class~="post"] {
  color: red;
}

/* if dashed "post" */
div[class|="post"] {
  color: red;
}

regex.html

<!-- if contains "post" -->
<div class="post-45"></div>
<div class="last-post"></div>
<div class="last-post-with-picture"></div>

<!-- if begins with "post" -->
<div class="post-45 col-3"></div>

<!-- if ends with "post" -->
<div class="col-3 with-picture 45-post"></div>

<!-- if space separated "post" -->
<div class="col-3 post with-picture"></div>

<!-- if dashed "post" -->
<div class="last-post-with-picture"></div>