#leftheader
{
padding: 30px;
float: left;
border: 1px solid black;
background-color: #2A2A2A;
color: white;
border-radius: 10px;
}
#leftheader > .leftprofile > progress
{
height: 8px;
background: #444;
border-radius: 10px;
}
#leftheader > .leftprofile > progress::-webkit-progress-bar {
background: transparent;
}
#leftheader > .leftprofile > progress::-webkit-progress-value
{
background: linear-gradient(to right, red, black);
border-radius: 10px;
}
<div class="leftprofile">
<img src="img/stats/health.png" alt=""> Health<br>
<progress value="100" max="100"></progress><br>
<img src="img/stats/energy.png" alt=""> Energy<br>
<progress value="90" max="100"></progress><br>
<img src="img/stats/drink.png" alt=""> Drink<br>
<progress value="70" max="100"></progress><br>
<img src="img/stats/food.png" alt=""> Food<br>
<progress value="60" max="100"></progress><br>
<img src="img/stats/hygiene.png" alt=""> Hygiene<br>
<progress value="100" max="100"></progress><br>
<img src="img/stats/exp.png" alt=""> Level 0<br>
<progress value="10" max="100"></progress><br>
</div>
Na Google Chrome działa, na Mozilli nie. Chodzi o kolory progrss baru, a konkretnie ten gradient.