Rambox-CE/ext/packages/ext-theme-base/sass/src/tab/Bar.scss

.#{$prefix}tab-bar {
    z-index: 0;
    position: relative;
}

.#{$prefix}tab-bar-body {
    position: relative;
}

.#{$prefix}tab-bar-strip {
    position: absolute;
    line-height: 0;
    font-size: 0;
    z-index: 2;

    .#{$prefix}tab-bar-top > & {
        bottom: 0;
    }

    .#{$prefix}tab-bar-bottom > &{
        top: 0;
    }

    .#{$prefix}tab-bar-left > & {
        right: 0;

        @if $include-rtl {
           &.#{$prefix}rtl {
                right: auto;
                left: 0;
            }
        }
    }

    .#{$prefix}tab-bar-right > & {
        left: 0;

        @if $include-rtl {
            &.#{$prefix}rtl {
                left: auto;
                right: 0;
            }
        }
    }
}

.#{$prefix}tab-bar-horizontal .#{$prefix}tab-bar-strip {
    width: 100%;
    left: 0;
}

.#{$prefix}tab-bar-vertical {
    // vertical tabbars use display:table-cell so that they doen't expand to fill their
    // container when rendered outside of a tabpanel. (display:table doesn't work in IE9
    // because getComputedStyle doesn't return the correct border/padding info)
    display: table-cell;

    .#{$prefix}tab-bar-strip {
        height: 100%;
        top: 0;
    }
}

.#{$prefix}tab-bar-plain {
    background: transparent !important;
}

.#{$prefix}box-scroller-plain {
    background-color: transparent !important;
}