Not all CSS formatting is being loaded by JSP

I'm working on a J2ee web project and in my JSP. CSS is being inconsistent when I deploy my application and I check out the front-end. I load the CSS file using

<style>
    <%@include file="/css/indexCSS.css"%>
</style>

and also I've used

<link rel="stylesheet" type="text/css" href="${pageContext.request.contextPath}/css/indexCSS.css"/> 

The thing is, both of these work, but not completely, and are very inconsistent and finicky. For example, I will change something on my CSS, save, and republish the server, and deploy my application, and it doesn't show the change. A lot of the CSS is being displayed, but not all of it. Sometimes it works for some reason a couple days later even if I didn't change some of the CSS code. Does anyone know why the code I'm using to load CSS is finicky?