#main{color:#444;border:1px solid;padding:4rem 2rem}#main.math{border-color:#0054a7}#main.science{border-color:#004714}.main_tit{margin:0 auto}.ac_menu{margin:0 auto 4rem;width:900px}.ac_wrap{margin:0 auto 20px;width:100%}.ac_wrap.show .ac_icon{transform:rotate(0);-ms-transform:rotate(0);-webkit-transform:rotate(0);-moz-transform:rotate(0)}.ac_wrap .ac_icon{transform:rotate(180deg);-ms-transform:rotate(180deg);-webkit-transform:rotate(180deg);-moz-transform:rotate(180deg)}.ac_header{display:block;width:100%;cursor:pointer;position:relative}.ac_body{display:none;padding:20px 30px;font-size:1.6rem;line-height:1.75}.ac_icon{position:absolute;right:1.1rem;top:10px;width:30px;height:30px}.math .ac_icon{background:url(/keirinkan/text/chu/h28textbook/parents_math/images/math_accordion_icon.png) no-repeat;background-size:30px 30px}.science .ac_icon{background:url(/keirinkan/text/chu/h28textbook/parents_science/images/science_accordion_icon.png) no-repeat;background-size:30px 30px}@media only screen and (max-width:768px){#main{width:92%;padding:3% 1% 4%;margin:0 3%}.ac_header img,.ac_menu,.main_tit{width:100%}.ac_wrap{margin-bottom:2.5rem}.ac_menu{margin:2.5rem 0}.ac_icon{right:3%;top:20%;width:5%;width:4.6%;height:50%;padding-top:.25%;background-size:contain!important}.ac_body{padding:4% 3.5%;line-height:1.5}}.return_top{margin:30px auto 70px;text-align:center}.return_top p{background-color:#DCDDDD;border-radius:25px;padding:10px 40px 10px 10px;font-size:19px;color:#727172;display:inline-block}.return_top p:before{content:"";width:0;height:0;margin-right:30px;display:inline-block;border-top:7px solid transparent;border-right:10px solid #727172;border-bottom:7px solid transparent;border-left:8px solid transparent}@media only screen and (max-width:768px){.main_bottom{width:92%;margin:0 4%}.return_top{margin:8% auto 16%}.return_top p{font-size:1em;margin-left:1%;padding:3% 5%}.return_top p:before{vertical-align:-.15em;border-top:.5em solid transparent;border-right:.8em solid #727172;border-bottom:.5em solid transparent;border-left:1px solid transparent;margin-right:.7em}}