Nick,
You can adjust the simpleslider by changing the css. Go to "[install location]\server\apps\[App#]\jimu.js\css\jimu.css and find this:
.esriSimpleSliderTL{
top: 5px;
left: 7px;
border: 0px solid #666;
background-color: rgba(255, 255, 255, 0.3);
}
And just adjust the top property to your liking.