meter {

    margin: 0 auto 1em;
    width: 98%;
    height: 0.5em;

    /* Applicable only to Firefox */
    background: none;
    background-color: rgba(0, 0, 0, 0.1);
}

meter::-webkit-meter-bar {
    background: none;
    background-color: rgba(0, 0, 0, 0.1);
}

/* Webkit based browsers */
meter[value="1"]::-webkit-meter-optimum-value { background: red; }
meter[value="2"]::-webkit-meter-optimum-value { background: red; }
meter[value="3"]::-webkit-meter-optimum-value { background: yellow; }
meter[value="4"]::-webkit-meter-optimum-value { background: orange; }
meter[value="5"]::-webkit-meter-optimum-value { background: green; }

/* Gecko based browsers */
meter[value="1"]::-moz-meter-bar { background: red; }
meter[value="2"]::-moz-meter-bar { background: red; }
meter[value="3"]::-moz-meter-bar { background: yellow; }
meter[value="4"]::-moz-meter-bar { background: orange; }
meter[value="5"]::-moz-meter-bar { background: green; }