Hi john1987,
in order to control the visibility of the scroll buttons inside the header section of the element you simply need to changed the <b>overview</b> property to ‘hidden’. When you want to see the buttons again just set the value of the property back to it’s default value ‘auto’. Here’s how to do it:

        window.onload = function () {
            var tabs = document.querySelector('smart-tabs');
            tabs.addEventListener('mouseenter', function (event) {
                this.overflow = 'auto';
            tabs.addEventListener('mouseleave', function (event) {
                this.overflow = 'hidden';
        <smart-tab-item label="TAB 1">Content 1</smart-tab-item>
        <smart-tab-item label="TAB 2">Content 2</smart-tab-item>
        <smart-tab-item label="TAB 3">Content 3</smart-tab-item>
        <smart-tab-item label="TAB 4">Content 4</smart-tab-item>
        <smart-tab-item label="TAB 5">Content 5</smart-tab-item>
        <smart-tab-item label="TAB 6">Content 6</smart-tab-item>
        <smart-tab-item label="TAB 7">Content 7</smart-tab-item>
        <smart-tab-item label="TAB 8">Content 8</smart-tab-item>
        <smart-tab-item label="TAB 9">Content 9</smart-tab-item>
        <smart-tab-item label="TAB 10">Content 10</smart-tab-item>
        <smart-tab-item label="TAB 11">Content 11</smart-tab-item>

If you have further questions feel free to ask.
Best Regards,
Smart HTML Elements Team