Make div 100% Width of Browser Window

.myDiv {
    background-color: red;
    width: 100%;
    min-height: 100vh;
    max-height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    margin: 0 auto;
}

Basically, we're fixing the div's position regardless of it's parent, and then position it using margin: 0 auto; and settings its position at the top left corner.

There are new units that you can use:

vw - viewport width

vh - viewport height

#neo_main_container1
{
   width: 100%; //fallback
   width: 100vw;
}

Help / MDN

Opera Mini does not support this, but you can use it in all other modern browsers.

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