Set a Fixed div to 100% width of the parent container

Question

I have a wrapper with some padding, I then have a floating relative div with a percentage width (40%).

Inside the floating relative div I have a fixed div which I w

Answer 1

Try adding a transform to the parent (doesn't have to do anything, could be a zero translation) and set the fixed child's width to 100%

body{ height:20000px }
#wrapper {padding:10%;}
#wrap{ 
    float: left;
    position: relative;
    width: 40%; 
    background:#ccc; 
    transform: translate(0, 0);
}
#fixed{ 
    position:fixed;
    width:100%;
    padding:0px;
    height:10px;
    background-color:#333;
}

    

    Some relative item placed item