Yes, there is. You can write a CSS stylesheet and include it in your exported html files.
You can set the global variables
org-html-head-extra to any HTML that you want to include in every exported file, or you can add directives to your .org files that override these variables just for that specific file. For example:
#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="style1.css" />
#+HTML_HEAD_EXTRA: <link rel="alternate stylesheet" type="text/css" href="style2.css" />
This and other useful information can be found in chapter 12.6.11 of the Org Mode manual. You can run
M-: (info "(org)CSS Support") to jump right to it.