CSS3 100매 윈도우 효과 윤방도 구현

<div class="main">
    <input type="radio" name="btn" id="btn1" checked>
    <label for="btn1">1label>
    <input type="radio" name="btn" id="btn2" >
    <label for="btn2">2label>
    <input type="radio" name="btn" id="btn3" >
    <label for="btn3">3label>
    <input type="radio" name="btn" id="btn4" >
    <label for="btn4">4label>
    <div class="content">
        <div>
            <span>span>
            <span>span>
            <span>span>
            <span>span>
        div>
        <div>
            <span>span>
            <span>span>
            <span>span>
            <span>span>
        div>
        <div>
            <span>span>
            <span>span>
            <span>span>
            <span>span>
        div>
        <div>
            <span>span>
            <span>span>
            <span>span>
            <span>span>
        div>
    div>
div>

*{ margin: 0; padding: 0; }
.main{ width: 900px; height: 500px; position: relative; }
.content{ width: 100%; height: 100%; }
.content>div{ width: 225px; height: 100%; background: #333; float: left; position: relative; overflow: hidden; }
.content>div span{ width: 100%; height: 100%; display: block; background: red; position: absolute; top: 0; left: 225px; }

input#btn1:checked~.content div span:nth-child(1){ background-image: url("./images/1.jpg") }
input#btn2:checked~.content div span:nth-child(2){ background-image: url("./images/2.jpg") }
input#btn3:checked~.content div span:nth-child(3){ background-image: url("./images/3.jpg") }
input#btn4:checked~.content div span:nth-child(4){ background-image: url("./images/4.jpg") }

.content div:nth-child(1) span{ background-position: 0px 0px; }
.content div:nth-child(2) span{ background-position: -225px 0px; }
.content div:nth-child(3) span{ background-position: -450px 0px; }
.content div:nth-child(4) span{ background-position: -675px 0px; }

input#btn1:checked ~ .content div span:nth-child(1),
input#btn2:checked ~ .content div span:nth-child(2),
input#btn3:checked ~ .content div span:nth-child(3),
input#btn4:checked ~ .content div span:nth-child(4)
        { left:0px; -webkit-transition:left 0.5s ease; }

label{ width:30px; height: 30px; background: #33FFFF; display:block; border-radius:15px; text-align:center; line-height:30px; position: absolute; z-index:333; top: 450px;}

input#btn1 + label{ left:700px; }
input#btn2 + label{ left:750px; }
input#btn3 + label{ left:800px; }
input#btn4 + label{ left:850px; }

input:checked + label{ background:#fff; border:5px solid #33FFFF; border-radius:20px;}
input{ display:none; }