html - 如何删除html按钮之间的空格？

Question

我不知道那些空间在那里以及如何删除它们。任何帮助将不胜感激

.square{
    width:50px;
    height:50px;
    background-color:#FF9500;
    color:#000;
    font-size:50px;
    text-align:center;
    line-height: 22px;
}

<div id="allbuttons">
    <div class="line">
        <button class = "square" id="b1">1</button>
        <button class = "square" id="b2">2</button>
        <button class="square" id="b3">3</button>  
    </div>
    <div class="line" >
        <button class = "square" id="b4">4</button>
        <button class = "square" id="b5">5</button>
        <button class="square" id="b6">6</button>  
    </div>
    <div class="line">
        <button class = "square" id="b7">7</button>
        <button class = "square" id="b8">8</button>
        <button class="square" id="b9">9</button>  
    </div>
    </div>

截屏

标签： htmlcss