jitsi-meet/css/_meter.scss

.jitsi-icon {
    &.metr {
        display: inline-block;

        & > svg {
            fill: #4E5E6C;
            width: 38px;
        }
    }

    &.metr--disabled {
        & > svg {
            fill: #4E5E6C;
        }
    }
}

.metr-l-0 {
    rect:first-child {
        fill: #31B76A;
    }
}

@for $i from 1 through 7 {
    .metr-l-#{$i} {
        rect:nth-child(-n+#{$i+1}) {
            fill: #31B76A;
        }
    }
}