CSS マウスオーバーで吹き出しを表示 | 私的雑録#menu div { position: relative; } .arrow_box { display: none; position: absolute; padding: 16px; -webkit-border-radius: 8px; -moz-border-radius: 8px; border-radius: 8px; background: #333; color: #fff; } .arrow_box:after { position: absolute; bottom: 100%; left: 50%; width: 0; height: 0; margin-left: -10px; border: solid transparent; border-color: rgba(51, 51, 51, 0); border-bottom-color: #333; bor
