Ghost/ghost/admin/app/styles/components/splitbuttons.css

/* Splitbuttons
/* ---------------------------------------------------------- */

.splitbtn {
    position: relative;
    display: inline-block;
    vertical-align: middle;
    /* Flatten out the right side */
    /* Flatten out the left side */
}

.splitbtn .gh-btn {
    position: relative;
    float: left;
    /* Prevent double border between buttons */
    /* Make sure the hovered element is always on
    // top so overlap from .gh-btn + btn. invisible */
}

.splitbtn .gh-btn + .gh-btn {
    margin-left: -1px;
}

.splitbtn .gh-btn:hover,
.splitbtn .gh-btn:focus,
.splitbtn .gh-btn:active,
.splitbtn .gh-btn.active {
    z-index: 2;
}

.splitbtn .gh-btn:first-child {
    margin-left: 0;
}

.splitbtn .gh-btn:first-child:not(:last-child):not(.dropdown-toggle) {
    height: 31px;
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
}

.splitbtn .dropdown-toggle {
    padding-right: 12px;
    padding-left: 12px;
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
    /* This is the additional dropdown arrow, to the right of the button. */
}

.splitbtn .dropdown-toggle.gh-btn-sm {
    padding-right: 10px;
    padding-left: 10px;
    height: 31px;
}

.splitbtn .dropdown-toggle.gh-btn-lg {
    padding-right: 16px;
    padding-left: 16px;
}

.splitbtn .dropdown-toggle .options {
    color: #fff;
    text-align: center;
}

.splitbtn .dropdown-toggle svg {
    height: 10px;
    fill: #fff;
}

.splitbtn .dropdown-toggle svg path {
    stroke: #fff;
    stroke-width: 2px;
}