モバイルメニュー全画面オーバーレイ

<div class="d11-03-10-phone">
          <div class="d11-03-10-screen">
            <div class="d11-03-10-bar">
              <span class="d11-03-10-logo">MySite</span>
              <button class="d11-03-10-burger" id="d11-03-10-burger" aria-label="メニュー"><span></span><span></span><span></span></button>
            </div>
            <div class="d11-03-10-body">ページ内容</div>
            <div class="d11-03-10-overlay" id="d11-03-10-ov">
              <button class="d11-03-10-x" id="d11-03-10-x" aria-label="閉じる">×</button>
              <nav class="d11-03-10-menu">
                <a style="--i:0">ホーム</a>
                <a style="--i:1">サービス</a>
                <a style="--i:2">実績紹介</a>
                <a style="--i:3">お問い合わせ</a>
              </nav>
            </div>
          </div>
        </div>

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        .d11-03-10-screen{position:absolute;inset:0;background:#f8fafc}
        .d11-03-10-bar{position:absolute;top:0;left:0;right:0;height:42px;display:flex;align-items:center;justify-content:space-between;padding:0 14px;background:#fff;border-bottom:1px solid #eef2f7;z-index:2}
        .d11-03-10-logo{font-size:13px;font-weight:700;color:#1e293b}
        .d11-03-10-burger{width:22px;height:16px;border:0;background:none;padding:0;cursor:pointer;position:relative}
        .d11-03-10-burger span{position:absolute;left:0;right:0;height:2px;background:#1e293b;border-radius:2px}
        .d11-03-10-burger span:nth-child(1){top:0}.d11-03-10-burger span:nth-child(2){top:7px}.d11-03-10-burger span:nth-child(3){top:14px}
        .d11-03-10-body{position:absolute;top:42px;left:0;right:0;bottom:0;display:flex;align-items:center;justify-content:center;color:#94a3b8;font-size:13px}
        .d11-03-10-overlay{position:absolute;inset:0;background:linear-gradient(160deg,#4f46e5,#7c3aed);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:6px;opacity:0;pointer-events:none;transition:opacity .35s;z-index:5}
        .d11-03-10-overlay.d11-03-10-on{opacity:1;pointer-events:auto}
        .d11-03-10-x{position:absolute;top:8px;right:12px;border:0;background:none;color:#fff;font-size:26px;line-height:1;cursor:pointer}
        .d11-03-10-menu{display:flex;flex-direction:column;align-items:center;gap:10px}
        .d11-03-10-menu a{color:#fff;font-size:15px;font-weight:600;opacity:0;transform:translateY(12px);cursor:pointer}
        .d11-03-10-overlay.d11-03-10-on .d11-03-10-menu a{animation:d11-03-10-in .4s forwards;animation-delay:calc(var(--i)*.08s + .1s)}
        @keyframes d11-03-10-in{to{opacity:1;transform:translateY(0)}}

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        var b=root.querySelector('#d11-03-10-burger'),ov=root.querySelector('#d11-03-10-ov'),x=root.querySelector('#d11-03-10-x');
        b.addEventListener('click',function(){ov.classList.add('d11-03-10-on');});
        x.addEventListener('click',function(){ov.classList.remove('d11-03-10-on');});
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