input输入框获得焦点、失去焦点效果
废话shao shuo ! 直接看效果图，好吧！
效果图：
code:
<!DOCTYPE html><html><head><title></title><meta charset="utf-8" /><style type="text/css">*{margin:0;padding:0;}#box{width:200px;height:30px;border-bottom:1px solid #a8a8a8;margin:30px auto;position:relative;}#box .input{width:100%;height:100%;outline:none;border:none;font-size:16px;}#box .line{width:0px;height:2px;background:#00aeff;position:absolute;bottom:-1px;left:50%;transform:translateX(-50%);transition:width 0.4s ease;}#box .placeh{position:absolute;left:4px;top:5px;transition:top 0.4s ease;color:#cbcbcb;}#box .placeh:hover{cursor:text;}#box .input:focus ~ .line{width:100%;}#box .input:focus ~ .placeh,#box .input:valid ~ .placeh{top:-26px;color:#00a2ff;}</style></head><body><div id="box"><input type="text" id="input" class="input" required ><span class="line"></span><label class="placeh" for="input">Enter your account</label></div></body><script></script></html>
---- 结束 ----
仅学习。
