css가 안먹히는 경우 ㅠㅠ

.mini_b{

 position:relative;

  top:100px; left:900px;

  width:180px; height: 65px;

  border:1px solid black;

  z-index: 9998;

  overflow: hidden;

}

.m_img {width:180px; height: 390px;
  position: absolute;;}

.m_img li{width:180px; height: 65px; }

.mini_b img{ display: none;}

.mini_b m_g1{display: block;}

.mini_nav { cursor: pointer;
   position: absolute;right:360px;}

#mini_prev{top:90px;}

#mini_next{top:120px;}

.m_g1{background-image: url(image/main/mbanner3.jpg);}
.m_g2{background-image: url(image/main/mbanner5.jpg);}
.m_g3{background-image: url(image/main/mbanner6.jpg);}
.m_g4{background-image: url(image/main/mbanner4.jpg);}
.m_g5{background-image: url(image/main/mbanner7.jpg);}
.m_g6{background-image: url(image/main/mbanner2.jpg);}
.m_g7{background-image: url(image/main/mbanner1.jpg);}

///////////////

<div class="mini_nav" id="mini_prev">
     <a href="#"><img src="image/main/m_b1.jpg"></a>
    </div>

    <div class="mini_b">  <!--mini_b-->

     <ul class="m_img" id="m_img">
        <li class="m_g1">
         <a href="#"></a>
       </li>
        <li class="m_g2">
         <a href="#"></a>
       </li> 
        <li class="m_g3">
         <a href="#"></a>
       </li>
        <li class="m_g4">
         <a href="#"></a>
       </li> 
        <li class="m_g5">
         <a href="#"></a>
       </li>
        <li class="m_g6">
         <a href="#"></a>
       </li>
        <li class="m_g7">
         <a href="#"></a>
       </li>
     </ul>

    </div> <!--mini_b-->

    <div class="mini_nav" id="mini_next">
     <a href="#"><img src="image/main/m_b2.jpg"></a>
    </div>

.​mini_b {} 가 전혀 안먹히는데 왜그런지 좀 알려주세요... ㅠㅠㅠㅠ 백그라운드를 줘도 안나타나고 아예 아무것도 안먹혀요 ㅠㅠㅠ