I have added bootstrap to my site. Here is the structure I am using. (I cannot whatsoever remove the bootstrap.css file since it I modified it to my liking).
You can also try this:
@font-face {
font-family: 'Glyphicons Halflings';
src: url('<%= asset_path("glyphicons-halflings-regular.eot") %>');
src: url('<%= asset_path("glyphicons-halflings-regular.eot?#iefix") %>') format('embedded-opentype'), url('<%= asset_path("glyphicons-halflings-regular.woff2") %>') format('woff2'), url('<%= asset_path("glyphicons-halflings-regular.woff") %>') format('woff'), url('<%= asset_path("glyphicons-halflings-regular.ttf") %>') format('truetype'), url('<%= asset_path("glyphicons-halflings-regular.svg#glyphicons_halflingsregular") %>') format('svg');
}
You just need to convert your your_css.css file to your_css.css.erb