title: Change Emacs theme with mode
body: <p>I would like to switch from 'solarized-dark (with my theme by default) to 'solarized-light when typing LATEX or Markdown.
  I'm using Emacs 24 and solarized from <a href="https://github.com/sellout/emacs-color-theme-solarized" rel="nofollow noreferrer">https://github.com/sellout/emacs-color-theme-solarized</a>.</p>
  <p>In my custom.el, I wrote the following lines :</p>
  <pre><code>(add-to-list 'custom-theme-load-path (make-plugin-path &quot;color-theme-solarized&quot;))
  (load-theme 'solarized 1)
  
  (add-hook 'markdown-mode-hook
        (lambda (frame)
          (set-frame-parameter frame 'background-mode 'light))
        )
  </code></pre>
  <p>But it doesn't work properly, i.e. loading a .md file does not make Emacs switch from 'dark to 'light solarized theme.</p>