<?xml version="1.0"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN"
    "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">

<svg width="300" height="300">

<rect x="10" y="10" width="200" height="20"
      style="stroke: black; fill: green; fill-opacity: 0.25;">

    <animate attributeName="width" attributeType="XML"
             from="20" to="250" begin="0s" dur="8s" fill="freeze"/>
    <animate attributeName="height" attributeType="XML"
             from="20" to="200" begin="0s" dur="8s" fill="freeze"/>
    <animate attributeName="fill-opacity" attributeType="CSS"
             from="0.25" to="1" begin="0s" dur="3s" fill="freeze"/>
    <animate attributeName="fill-opacity" attributeType="CSS"
             from="1" to="0.25" begin="3s" dur="3s" fill="freeze"/>
</rect>

</svg>