*{ box-sizing: border-box; padding: 0; margin: 0; } :root { --grid-cols: 1; --grid-rows: 1; } #container { display: grid; /*grid-template-rows: repeat(var(--grid-rows), 1fr); not working in Firefox*/ grid-auto-rows: calc(100vh/var(--grid-rows)); grid-auto-columns: calc(100vw/var(--grid-cols)); grid-template-columns: repeat(var(--grid-cols), 1fr); width: 100vw; height: 100vh; } .grid-item { border: none; background-color: #fff; text-align: center; } .grid-item-invis{ border: none; text-align: center; width: 0px; height: 0px; background-color: #fff; } .formbutton{ position: relative; top: -6em; right: 2em; z-index: 9; padding: 1em; float: right; }