With the CSS Grid Layout Module soon shipping in Firefox and Chrome, I thought that I'd try to get a handle of how to use it.

I've tried to create a simple grid with one item a spanning the left side of all of the rows, with the other items (b, c, d, e, etc.) spanning the right side of individual rows. The amount of items spanning the right side of the rows is variable, so there might be any combination of b, c, d, e, etc., so I'm using the grid-auto-rows property. As such, I cannot define a fixed number of rows for a to span, but I would like a to span all available rows.

#container {
    display: grid;
    grid-auto-flow: column;
    grid-auto-rows: auto;
    grid-template-columns: [left] 4rem [right] 1fr;
    margin: 0rem auto;
    max-width: 32rem;
}
#a {
    background: lightgreen;
    grid-column: left;
    grid-row: 1 / auto;
    justify-self: center;
}
#b {
    grid-area: auto / right;
    background: yellow;
}
#c {
    grid-area: auto / right;
    background: pink;
}
#d {
    grid-area: auto / right;
    background: lightskyblue;
}
#e {
    background: plum;
    grid-area: auto / right;
}

    
a
    
b
    
c
    
d
    
e

What should I do to make a span all rows without knowing how many rows there will end up being?