canvas.css

.drag-in-progress .drop-target-placeholder {
    border: 1px dotted #ababab;
    background-color: #ffffaa;
    min-height: 36px;
    min-width: 36px;
    max-width: 100%;
    vertical-align: middle;
    display: block;
}

.drag-in-progress .drop-target-placeholder.button,
.drag-in-progress .drop-target-placeholder.text,
.drag-in-progress .drop-target-placeholder.input {
    display: inline-block;
}

.overlay-body {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 10;
    cursor: pointer;
}

html, body, body > div {
    height: 100%;
    overflow: hidden;
}

body > div div {
    border: 1px dashed #d7d7d7;
    margin: 2px;
    padding: 2px;
    min-height: 40px;
}

button, input, span {
    margin: 2px;
}