How should I use fixed centering layout?

[ferret]

This is my container.
position: fixed;
top: 1em;
left: 50%;
transform: translateX(-50%);
However, its actual effect is like this.

[ferret]

position: fixed;
width: 100vw;
display: flex;
flex-direction: column;
align-items: center;
pointer-events: none;
top: 1em;
z-index: 99999;
I solved it using 100% width and flex layout.