Make font sizes specified not in pixels, but something fluent and responsive like 'ems' or percent.

[RobertLRead]

I'd like to not use pixels for font sizes and margins to try to keep the GUI as responsive as possible to resolution changes (phone or Raspberry PI to giant Mac screen.) I think the last pull request created some code like:

    <div class="vertical_alarms">
          <div class="limit-max">
            <label for="max_h">H:</label>
            <slot name="obs-max">111</slot>
            <input style="font-size: 50px; margin: 100px 30px 0 10px;" class="fence" 

Also, I would much rather that be placed on the "limit-max" or "fence" class in the .css and moved to .css file completely.