size watcher v3

The final result

by smnh

HTML

<div id="stage" class="preserve3d">
    <div id="contentShadow" class="preserve3d">
        <div class="bottomLayer preserve3d">
            <div class="bottomLayer">
                <div id="innerContentShadow">
                    <div id="innerScrollTopBrace" class="scrollTopBrace"><div class="scrollTopLabelWrapper"><div class="scrollTopLabel">scrollTop: <span id="innerScrollTopValue"></span></div></div></div>
                    <div class="label">inner content</div>
                </div>
            </div>
            <div id="innerWrapper" class="wrapper"><div id="innerContent"></div></div>
            <div class="label">inner wrapper</div>
            <div id="innerScrollLabel" class="scrollLabel">scrolled</div>
        </div>
        <div id="scrollTopBrace" class="scrollTopBrace"><div class="scrollTopLabelWrapper"><div class="scrollTopLabel">scrollTop: <span id="scrollTopValue"></span></div></div></div>
        <div class="label">content</div>
        <div id="decreaseHeightButton">&#9650; -40px</div>
        <div id="increaseHeightButton">&#9660; +40px</div>
    </div>
    <div id="topLayerWrapper" class="topLayer">
        <div id="wrapper" class="wrapper"><div id="content"></div></div>
        <div class="label">wrapper</div>
        <div id="scrollLabel" class="scrollLabel">scrolled</div>
    </div>
</div>

CSS

#stage {
    position:absolute;
    top:180px;
    left:230px;
    font-size: 20px;
    /* for browsers not supporting 3d transforms fallback to this */
    -webkit-transform: rotate(-30deg) skew(10deg);
    -moz-transform: rotate(-30deg) skew(10deg);
    -ms-transform: rotate(-30deg) skew(10deg);
    transform: rotate(-30deg) skew(10deg);
    /* for browsers supporting 3d transforms */
    -webkit-transform: rotateX(45deg) rotateZ(-35deg);
    -moz-transform: rotateX(45deg) rotateZ(-35deg);
    -ms-transform: rotateX(45deg) rotateZ(-35deg);
    transform: rotateX(45deg) rotateZ(-35deg);
}
#topLayerWrapper {
    position: absolute;
    width: 200px;
    height: 200px;
}
#content {
    height: 300px;
}
#contentShadow {
    position:absolute;
    background-color: #999999;
}
#decreaseHeightButton, #increaseHeightButton {
    position: absolute;
    left: -104px;
    width: 100px;
    height: 38px;
    line-height: 38px;
    text-align: center;
    border: 1px solid #999999;
    background-color: #cccccc;
    cursor: pointer;
}
#decreaseHeightButton {
    bottom: 1px;
}
#increaseHeightButton {
    bottom: -41px;
}
#innerContent {
    height: 400px;
}
#innerContentShadow {
    position: absolute;
    width: 100%;
    height: 400px;
    background-color: #cccccc;
}
.scrollTopBrace {
    position: absolute;
    top: 0;
    width: 10px;
    border: 2px solid #333333;
}
#scrollTopBrace {
    right: -15px;
    border-left-width: 0;
}
#innerScrollTopBrace {
    left: -15px;
    border-right-width: 0;
}
.scrollTopLabelWrapper {
    position: absolute;
    top: 50%;
}
.scrollTopLabel {
    position: absolute;
    white-space: nowrap;
}
#scrollTopBrace .scrollTopLabel {
    -webkit-transform: translate(20px, -50%);
    -moz-transform: translate(20px, -50%);
    -ms-transform: translate(20px, -50%);
    transform: translate(20px, -50%);
}
#innerScrollTopBrace .scrollTopLabel {
    -webkit-transform: translate(-105%, -50%);
    -moz-transform: translate(-105%, -50%);
   ...

JavaScript

var content = document.getElementById("content"),
    decreaseHeightButton = document.getElementById("decreaseHeightButton"),
    increaseHeightButton = document.getElementById("increaseHeightButton"),
    
    wrapper = document.getElementById("wrapper"),
    scrollLabel = document.getElementById("scrollLabel"),
    contentShadow = document.getElementById("contentShadow"),
    scrollTopBrace = document.getElementById("scrollTopBrace"),
    scrollTopValue = document.getElementById("scrollTopValue"),
    scrollLabelHideTimeout = null,
    
    innerWrapper = document.getElementById("innerWrapper"),
    innerScrollLabel = document.getElementById("innerScrollLabel"),
    innerContentShadow = document.getElementById("innerContentShadow"),
    innerScrollTopBrace = document.getElementById("innerScrollTopBrace"),
    innerScrollTopValue = document.getElementById("innerScrollTopValue"),
    innerScrollLabelHideTimeout = null;

function updateScrollTop() {
    contentShadow.style.top = -wrapper.scrollTop + "px";
    scrollTopBrace.style.height = wrapper.scrollTop + "px";
    scrollTopValue.textContent = wrapper.scrollTop + "px";
}

function updateInnerScrollTop() {
    innerContentShadow.style.top = -innerWrapper.scrollTop + "px";
    innerScrollTopBrace.style.height = innerWrapper.scrollTop + "px";
    innerScrollTopValue.textContent = innerWrapper.scrollTop + "px";
}

function updateContentShadowSize() {
    contentShadow.style.width = content.offsetWidth + "px";
    contentShadow.style.height = content.offsetHeight + "px";
}

function showScrollLabel() {
    scrollLabel.className = "scrollLabel show";
    window.clearTimeout(scrollLabelHideTimeout);
    scrollLabelHideTimeout = window.setTimeout(hideScrollLabel, 500);
}

function hideScrollLabel(e) {
    scrollLabel.className = "scrollLabel hide";
    scrollLabelHideTimeout = null;
}

function showInnerScrollLabel() {
    innerScrollLabel.className = "scrollLabel show";
   ...