css中按鈕有四種狀態

1. 普通狀態
2. hover 鼠標懸停狀態
3. active 點擊狀態
4. focus 取得焦點狀態

.btn:focus{outline:0;} 可以去除按鈕或a標簽點擊後的藍色邊框

下面的例子中.btn1用focus按鈕會按下，不彈起
　　　　　　.btn2用active按鈕點擊按下，會彈起

<button class="btn btn1">Save Settings</button>
<button class="btn btn2">Submit</button>

.btn{
    appearance
 
: none;
    background: #026aa7;
    color: #fff;
    font-size: 20px;
    padding: 0.65em 1em;
    border-radius: 4px;
    box-shadow: inset 0 -4px 0 0 rgba(0,0,0,0.2);
    margin-right: 1em;
    cursor: pointer;
    border:0;
}
.btn1:hover{
    box-shadow: inset 0 -4px 0 0 rgba(0,0,0,0.6), 0 0 8px 0 rgba(0,0,0,0.5);
}
.btn1:focus
 
{
    position: relative;
    top: 4px;
    box-shadow: inset 0 3px 5px 0 rgba(0,0,0, 0.2);
    outline: 0;
}
.btn2:hover{
    box-shadow: inset 0 -4px 0 0 rgba(0,0,0,0.6), 0 0 8px 0 rgba(0,0,0,0.5);
}
.btn2:active{
    position: relative;
    top: 4px;
    box-shadow: inset 0 3px 5px 0 rgba(0,0,0,0.2);
    outline: 0;
}
.btn2:focus
 
{
    outline: 0;
}

css中按鈕的四種狀態