var UI_TEMPLATE = [
  '<div id="curtain" style="opacity:0;width:100%;height:100%;margin:0;padding:0;position:absolute;top:0;left:0;background:rgba(255,255,255,0.1);"></div>',
  '<div id="outline" style="border:1px solid white;background:rgba(0,255,255,0.5);opacity:0.5; position: absolute;pointer-events:none"></div>',
  '<div id="controls" style="position: absolute;top:50px;right:50px;background:rgba(0,0,0,0.8);color:#fff;font-size:14px;min-width:300px; padding: 4px;cursor:default;">',
  'frames <input type="text" id="framecount" value="30" style="width:30px;">',
  'delay <input type="text" id="framedelay" value="0.06s" style="width:30px;">',
  '<button id="record" disabled>record</button>',
  '<button id="save" disabled>save</button>',
  '<span id="status"></span>',
  '<br>',
  'w <input type="text" id="w_el" value="" style="width:30px;"> ',
  'h <input type="text" id="h_el" value="" style="width:30px;"> ',
  'x <input type="text" id="x_el" value="" style="width:30px;"> ',
  'y <input type="text" id="y_el" value="" style="width:30px;"> ',
  '<br>',
  '<div id="preview"></div>',
  '</div>'
].join("")