<svg width="100px" height="100px" viewBox="0 0 100 100">

<line x1="10" y1="15" x2="50" y2="15"
    style="stroke: black;  stroke-width: 15;
    stroke-linecap: buttroundsquare;"/>
<!-- guide lines -->
<line x1="10" y1="0" x2="10" y2="25" style="stroke: #999;"/>
<line x1="50" y1="0" x2="50" y2="25" style="stroke: #999;"/>
</svg>