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CSS

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HTML 

              
                <div class="wrapper">
  <h3>タブ</h3>
  <div class="c-tab js-tab">
    <div class="c-tab__nav" role="tablist">
        <button class="c-tab__nav--item js-tab__item" role="tab" aria-selected="true" aria-controls="tab01" id="tab-nav01">tab01</button>
        <button class="c-tab__nav--item js-tab__item" role="tab" aria-selected="false" aria-controls="tab02" id="tab-nav02" tabindex="-1">tab02</button>
        <button class="c-tab__nav--item js-tab__item" role="tab" aria-selected="false" aria-controls="tab03" id="tab-nav03" tabindex="-1">tab03</button>
    </div>

    <div class="c-tab__pane js-tab__pane" tabindex="0" role="tabpanel" id="tab01" aria-labelledby="tab-nav01">
        <h4>Tab01</h4>
        <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Architecto unde consequatur accusamus quae atque? Distinctio, necessitatibus impedit ipsum, itaque id corrupti error, sunt odio facere architecto suscipit aliquam veniam delectus?</p>
    </div>
    <div class="c-tab__pane js-tab__pane" tabindex="0" role="tabpanel" id="tab02" aria-labelledby="tab-nav02" hidden="hidden">
        <h4>Tab02</h4>
        <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Architecto unde consequatur accusamus quae atque? Distinctio, necessitatibus impedit ipsum, itaque id corrupti error, sunt odio facere architecto suscipit aliquam veniam delectus?</p>
    </div>
    <div class="c-tab__pane js-tab__pane" tabindex="0" role="tabpanel" id="tab03" aria-labelledby="tab-nav03" hidden="hidden">
        <h4>Tab03</h4>
        <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Architecto unde consequatur accusamus quae atque? Distinctio, necessitatibus impedit ipsum, itaque id corrupti error, sunt odio facere architecto suscipit aliquam veniam delectus?</p>
    </div>
  </div>

 </div>
!

CSS 

              
                $tab-border-color:#eee;
$tab-border-radius:4px;
$tab-active-color:#3e82ff;

body{
  font-family: "Helvetica Neue",Arial,"Hiragino Kaku Gothic ProN","Hiragino Sans",Meiryo,sans-serif;
  color: #122322;
}
.wrapper{
  padding: 0 10px;
}

.c-tab{
	.c-tab__nav{
    display: flex;
    flex-wrap: wrap;
    margin-left: -2px;
    margin-right: -2px;
    margin-bottom: 20px;
    border-bottom: 1px solid $tab-border-color;
		.c-tab__nav--item{
      position: relative;
      -webkit-appearance: none;
      -ms-progress-appearance: none;
      appearance: none;
      cursor:pointer;
      margin: 0 2px -1px;
      background: none;
      display: block;
      text-align: left; 
      padding: 10px 20px;
      font-size: 14px;
      color:currentColor;
      border: 1px solid $tab-border-color;
      border-bottom-color: transparent;
      border-radius:$tab-border-radius $tab-border-radius 0 0;
      transition: background-color 0.3s cubic-bezier(0.19, 1, 0.22, 1), border-color 0.3s cubic-bezier(0.19, 1, 0.22, 1);
      &:hover{
        background-color: #f2f2f2;
      }
      &:focus:not(:focus-visible){
        outline: 0;
      }
      &.c-tab__active{
        background-color:#fff;
        color: $tab-active-color;
        border-color: $tab-border-color;
        border-bottom-color: #fff;
      }
      
    }
	}
	.c-tab__pane{
		  display: none;
      &.c-tab__active{
        display: block;
      }
	}
}
!

JS 

              
                class Tab {
    constructor(){
        this.tab_wrapper = '.js-tab'
        this.tab_item = '.js-tab__item'
        this.tab_pane = '.js-tab__pane'
        this.active_class = 'c-tab__active'

        this.keys = {   
            "left": 37,
            "up": 38,
            "right": 39,
            "down": 40
        }
        this.init()
    }
    init(){
        this.tab = document.querySelectorAll(this.tab_wrapper);
        this.tab_navs = [];
    
        if(this.tab.length > 0){
            this.tab.forEach( (tab,i) => {
                const tab_items = tab.querySelectorAll( this.tab_item );
                this.tab_navs.push( tab_items )

                if(tab_items.length > 0){
                    tab_items.forEach( (tab_nav,index) => {
                        if(index == 0){
                            const pane_id = tab_nav.getAttribute('aria-controls');
                            this._open(tab_nav,pane_id)
                        }
                        this._addEvent(tab_nav,i,index,tab_items);
                    })
                }
            })
        }	
		
    }

    _addEvent (el,i,index,tab_items){
        
        el.addEventListener('click',(e) => {
            
            this._hide(i);

            const pane_id = el.getAttribute('aria-controls');
            this._open(el,pane_id)
        })
        el.addEventListener('keydown',(e)=>{
            const k = e.which || e.keyCode;
            let position = index
            if (k >= this.keys.left && k <= this.keys.down){
                if (k == this.keys.left || k == this.keys.up){
                    if (position > 0) {
                        e.preventDefault()
                        position--
                        tab_items[position].click()
                        tab_items[position].focus()
                    }
                }else if (k == this.keys.right || k == this.keys.down){
                    if (position < tab_items.length-1 ) {
                        e.preventDefault()
                        position++
                        tab_items[position].click()
                        tab_items[position].focus()
                    }
                }
            }
        })
    }
    _open(item,pane_id){
        const target_pane = document.querySelector( '#' + pane_id );
        if ( !target_pane ) return;

        item.classList.add(this.active_class);
        item.setAttribute("aria-selected",true)
        item.setAttribute("tabindex",0)
        target_pane.classList.add(this.active_class);
        target_pane.removeAttribute("hidden")
    }
    _hide (i){
        const tab = this.tab[i]
        const item_active = tab.querySelector(this.tab_item+'.'+this.active_class);
        const pane_active = tab.querySelector(this.tab_pane+'.'+this.active_class);
        if(item_active){
            item_active.classList.remove(this.active_class);
            item_active.setAttribute("aria-selected",false)
            item_active.setAttribute("tabindex","-1")
        }
        if(pane_active){
            pane_active.classList.remove(this.active_class);
            pane_active.setAttribute("hidden","hidden")
        }
    }
 }

document.addEventListener('DOMContentLoaded', ()=>{
  new Tab
})
!
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