Ghost/core/client/assets/sass/components/splitbuttons.scss

//
// Base Splitbutton
// --------------------------------------------------

%splitbtn {
    display: inline-block;
    position: relative;
    font-size: 0; // hack to stop space after button
    white-space: nowrap;

    button {
        font-size: 11px; // hack to restore font size
        @include border-right-radius(0);
    }

    // This is the additional dropdown arrow, to the right of the button.
    .options {
        display: inline-block;
        position:relative;
        width: 35px;
        height: 35px;
        margin-left: -1px;
        vertical-align: top;
        text-align: center;
        color: #fff;
        background: #e5e5e5;
        border-radius: 0 2px 2px 0;
        border-left: 0;
        box-shadow:
            rgba(0,0,0,0.02) 0 1px 0 inset,
            rgba(0,0,0,0.02) -1px 0 0 inset,
            rgba(0,0,0,0.02) 0 -1px 0 inset;

        @include icon($i-chevron-down, 9px) {
            position: absolute;
            top: 50%;
            right: 50%;
            margin-top: -3px;
            margin-right: -5px;
            @include transition(margin-top 0.3s ease);
            /* Transition of transform properties are split out due to a
                defect in the vendor prefixing of transform transitions.
                See: http://github.com/thoughtbot/bourbon/pull/86 */
            @include transition-property(transform);
            @include transition-duration(0.3);
            @include transition-timing-function(ease);
        };

        @include transition(background-color 0.3s linear);

        // Keep the arrow spun when the associated menu is open
        &.active:before {
            @include transform(rotate(360deg));
        }

        &.up.active:before {
            margin-top:-4px;
            @include transform(rotate(540deg));
        }

        // Spin the arrow on hover and while menu is open
        &:hover,
        &:focus {
            will-change: box-shadow, background;
            box-shadow: none;
            background: #f8f8f8;
            @include icon($i-chevron-down) {
                will-change: transform;
                @include transform(rotate(360deg));
            };
        }

        // If it has a class of "up" spin it an extra 180degress to point up
        &.up:hover,
        &.up:focus {
            @include icon($i-chevron-down) {
                margin-top:-4px;
                @include transform(rotate(540deg));
                @include transition-property(transform);
                @include transition-duration(0.6);
                @include transition-timing-function(ease);
            };
        }
    }
}


//
// The Splitbuttons
// --------------------------------------------------

// The default splitbutton
.splitbutton {
    @extend %splitbtn;
    .options {
        color:#777;
        &:hover,
        &:focus {
            box-shadow:
                rgba(0,0,0,0.07) 0 1px 0 inset,
                rgba(0,0,0,0.07) -1px 0 0 inset,
                rgba(0,0,0,0.07) 0 -1px 0 inset;
        }
    }
}

// For save/next/continue/confirm actions
.splitbutton-save {
    @extend %splitbtn;
    .options {
        background: darken($blue, 5%);
        &:hover,
        &.active,
        &:focus {
            background: darken($blue, 10%);
        }
    }
}

// For actions which add something
.splitbutton-add {
    @extend %splitbtn;
    .options {
        background: darken($green, 6%);
        &:hover,
        &:focus {
            background: darken($green, 8%);
        }
    }
}

// For actions which delete something
.splitbutton-delete {
    @extend %splitbtn;
    .options {
        background: darken($red, 6%);
        &:hover,
        &:focus {
            background: darken($red, 10%);
        }
    }
}

// Alternative style with more visual attention, 
// but no extra semantic meaning
.splitbutton-alt {
    @extend %splitbtn;
    .options {
        background: lighten($darkgrey, 4%);
        &:hover,
        &:focus {
            background: $darkgrey;
        }
    }
}