Style references need to be relative.

There are two style sheet references:

<link rel="stylesheet" href="/theme/css/main.css">

<link rel="stylesheet" href="/theme/css/solarized-light.css">

These should be relative as either

<link rel="stylesheet" href="theme/css/main.css">

<link rel="stylesheet" href="theme/css/solarized-light.css">

or

<link rel="stylesheet" href="./theme/css/main.css">

<link rel="stylesheet" href="./theme/css/solarized-light.css">