zulip/static/styles/input_pill.css

.pill-container {
    display: inline-block;

    padding: 2px;
    border: 1px solid hsl(0, 0%, 86%);
    border-radius: 4px;

    font-size: 0.9em;

    cursor: text;
}

.pill-container .pill {
    position: relative;
    display: inline-block;

    padding: 0px 18px 0px 2px;
    margin: 1px 1px;

    color: #5db7b3;
    border: 1px solid #b2e4e2;

    border-radius: 4px;

    cursor: pointer;
}

.pill-container .pill:focus {
    color: #b85e5e;
    border: 1px solid #e4b2b2;

    outline: none;
}

.pill-container .input {
    display: inline-block;
    padding: 2px 4px;

    min-width: 2px;

    outline: none;
}

.pill-container .pill .exit {
    content: "\D7";
    position: absolute;
    top: 0px;
    right: 3px;

    opacity: 0.5;

    font-size: 1.3em;
}

.pill-container .pill:hover .exit {
    opacity: 1;
}

.pill-container .input.shake {
    animation: shake 0.3s cubic-bezier(.36,.07,.19,.97) both;
    transform: translate3d(0, 0, 0);
    backface-visibility: hidden;
    perspective: 1000px;
}

.pm_recipient .pill-container {
    position: absolute;
    left: 56px;
    width: 100%;
    height: 24px;

    border-top-left-radius: 0px;
    border-bottom-left-radius: 0px;
}

.pm_recipient .pill-container .pill {
    color: #fff;
    border: 1px solid #36a29b;
    background: #51c1af;
    font-weight: 600;
}

.pm_recipient .pill-container .pill:focus {
    border: 1px solid #108179;
    background: #36a29b;
}

.pm_recipient .pill-container .input {
    height: 12px;
}

@keyframes shake {
    10%, 90% {
        transform: translate3d(-1px, 0, 0);
    }

    20%,
    80% {
        transform: translate3d(2px, 0, 0);
    }

    30%,
    50%,
    70% {
        transform: translate3d(-3px, 0, 0);
    }

    40%,
    60% {
        transform: translate3d(3px, 0, 0);
    }
}