如何使div始终位于浏览器窗口的最左侧?

试试这个:

div#mydiv {
    position: fixed;
    left: 0;
}

top 或 bottom

比如:

div#mydiv {
    position: fixed;
    left: 0;
    top: 200px; /* 200px from top */
}

或:

div#mydiv {
    position: fixed;
    left: 0;
    bottom: 200px; /* 200px from bottom */
}

div#mydiv {
    position: fixed;
    left: 0;
    top: 50%; /* Half way down the side */
}

设置其 position fixed 以及它的 left 到 0px

#fixedLeft{
    position:fixed; /* now it will stay fixed on the screen, even while you scroll*/
    left:0px; /* it will be stuck to the left*/
    top:50%; /* it will be in the middle (vertically)*/
}