CSS自适应布局实现子元素项目整体居中，内部项目左对齐

<div class="wrap">
    <button class="btn">1</button>
    <button class="btn">2</button>
    <button class="btn">3</button>
    <button class="btn">4</button>
    <button class="btn">5</button>
    <button class="btn">6</button>
    <button class="btn">7</button>
</div>

.wrap {
    border: 2px solid black;
    margin: 0 auto;
    padding: 10px;
    width: 40%;
}
.btn {
    outline: none;
    border: none;
    width: 180px;
    height: 30px;
    background-color: cornflowerblue;
    margin: 5px;
}

.wrap {
    border: 2px solid black;
    margin: 0 auto;
    padding: 10px;
    width: 40%;
    display: grid;
    grid-template-columns: repeat(auto-fill, 200px);
    justify-content: center;
}
.btn {
    outline: none;
    border: none;
    width: 180px;
    height: 30px;
    background-color: cornflowerblue;
    margin: 5px;
}