Set element width or height in Standards Mode
The style
property lets you specify values for CSS properties.
The CSS width
property takes a length as its value.
Lengths require units. In quirks mode, browsers tend to assume pixels if provided with an integer instead of a length. Specify units.
e1.style.width = "400px";
Try declaring the unit of width:
e1.style.width = "400px"; // width in PIXELS