Css Question About Z Index

Ive got the product options matrix on this page, but want to be able to make it wider 700px, but when I alter the width in ff inspector it drops the whole lot to the bottom of the page. I thought i could an it as relative position and adding z index may make it stand alone but doesnt work.

does anyone know what i should do to ba able to make it wider but NOT have it drop down the page

https://www.hivis.co.uk/uneek-classic-polo-shirt-uc101.html

https://prnt.sc/gdo1k4this is what i need

this is what happens

http://prntscr.com/gdo1y1

.options-table-div table tbody {
display: block;
max-height: 250px;
overflow-y: auto;
overflow-x: auto;
max-width: 460px;
}

Please try

.options-table-div table tbody{
 max-width: 650px;
}
@media (min-width: 1224px) {
  .ty-product-detail .ty-product-block__left {
    padding-right: 0px;
  }
}

http://prntscr.com/gdwcuy

(!) Additional changes will be required for mobile version