JUMLY can change arrow style
A JavaScript library, JUMLY, is to render UML sequence diagrams. It can change styles whatever you want even arrows.
Here is a simple example.
On the other hand, here is a styled one.
Here is the style. Put this in your <style>
.sequence-diagram .message svg.arrow line {
stroke-width: 3px;
stroke: #8bc84b;
stroke-dasharray: 8, 4;
}
.sequence-diagram .message svg.arrow polyline {
stroke: #8bc84b;
fill: #8bc84b;
}
As you can see, arrow is rendered with SVG. So many properties are prepared. In detail, please see here, http://www.w3.org/TR/SVG/styling.html#SVGStylingProperties.