class '.close' of bootstrap breaks layout of code snippets when you use _close.scss of Bootstrap.

[Mishurin]

I think, it is reasonable to add some styles for .close class since it is used for styling in rainbow. For example,
.rainbow {
.close {
float: none;
font-size: inherit;
font-weight: inherit;
line-height: inherit;
text-shadow: none;
opacity: 1;
filter: none;
&:hover,
&:focus {
color: inherit;
text-decoration: inherit;
cursor: inherit;
opacity: 1;
}
}
}
This means, that in scope of .rainbow we have defined styles for .close class.

[Mishurin]

Otherwise you will get broken html code examples as I got.

[htanjo]

Thank you for reporting!
Actually we can prevent the layout issue by overriding with .rainbow .close { ... }, but I don't think it's perfect. (see: ccampbell/rainbow#101)

I'm planning to switch the syntax highlighting library itself.
I will choose a new library that uses high compatibility class names, like .some-prefix-close.