zulip/web/styles/progress_bar.css

@keyframes progress-bar-stripes {
    from {
        background-position: 40px 0;
    }

    to {
        background-position: 0 0;
    }
}

.progress {
    overflow: hidden;
    height: 20px;
    margin-bottom: 20px;
    background: linear-gradient(to bottom, hsl(0deg 0% 96%), hsl(0deg 0% 98%));
    background-repeat: repeat-x;
    box-shadow: inset 0 1px 2px hsl(0deg 0% 0% / 10%);
    border-radius: 4px;
}

.progress .bar {
    width: 0%;
    height: 100%;
    color: hsl(0deg 0% 100%);
    float: left;
    background: linear-gradient(
        to bottom,
        hsl(200deg 84% 48%),
        hsl(200deg 96% 38%)
    );
    background-repeat: repeat-x;
    box-shadow: inset 0 -1px 2px hsl(0deg 0% 0% / 15%);
    box-sizing: border-box;
    transition: width 0.6s ease; /* stylelint-disable-line plugin/no-low-performance-animation-properties */
}

.progress.active .bar {
    animation: progress-bar-stripes 2s linear infinite;
}

.progress .bar-danger {
    background: linear-gradient(
        to bottom,
        hsl(2deg 81% 65%),
        hsl(3deg 57% 49%)
    );
    background-repeat: repeat-x;
}

.progress .bar-success {
    background: linear-gradient(
        to bottom,
        hsl(120deg 45% 58%),
        hsl(120deg 32% 50%)
    );
    background-repeat: repeat-x;
}