.legacy-sidebar section:first-child{position:relative;overflow:hidden;padding:18px;background:linear-gradient(155deg,#10151a 0%,#060809 78%);border:1px solid #242b30;box-shadow:0 18px 42px rgba(0,0,0,.22)}
.legacy-sidebar section:first-child:before{content:"";position:absolute;right:-70px;top:-85px;width:190px;height:190px;border:1px solid rgba(25,168,239,.2);border-radius:50%;box-shadow:0 0 70px rgba(25,168,239,.12)}
.legacy-sidebar section:first-child>h2{position:relative;margin:-18px -18px 16px;padding:20px 20px 16px;background:transparent;border-bottom:1px solid #263038;font:800 21px/1 'Arial Narrow',Arial,sans-serif;letter-spacing:.07em}
.legacy-sidebar section:first-child>h2:after{content:"MENU  /  メニュー";display:block;margin-top:8px;color:#687580;font:700 9px/1 Arial,sans-serif;letter-spacing:.2em}
.sidebar-video-menu{position:relative;margin:0 0 7px;border:1px solid #232c32;background:#111619;overflow:hidden;transition:border-color .25s ease,transform .25s ease}
.sidebar-video-menu:hover,.sidebar-video-menu[open]{border-color:#19a8ef}
.sidebar-video-menu summary{list-style:none;cursor:pointer;display:flex;align-items:center;min-height:50px;padding:11px 16px;color:#f5f8fa;font-weight:700;letter-spacing:0;user-select:none}
.sidebar-video-menu summary::-webkit-details-marker{display:none}
.sidebar-video-menu summary:after{content:"";margin-left:auto;margin-right:1px;width:8px;height:8px;border-right:2px solid #19a8ef;border-bottom:2px solid #19a8ef;transform:rotate(45deg) translateY(-3px);transition:transform .2s ease}
.sidebar-video-menu[open] summary:after{transform:rotate(225deg) translate(-2px,-2px)}
.sidebar-video-menu nav{display:grid;gap:7px;padding:0 10px 11px}
.legacy-sidebar .sidebar-video-menu nav>a{display:grid!important;grid-template-columns:38px 1fr!important;grid-template-rows:auto auto;column-gap:2px;margin:0!important;padding:11px 12px 11px 8px!important;border:1px solid transparent!important;border-radius:3px;background:#151b1f!important;color:#edf3f6!important;text-decoration:none;position:relative;transition:background .2s ease,border-color .2s ease,transform .2s ease}
.legacy-sidebar .sidebar-video-menu nav>a:before{content:"";grid-column:1;grid-row:1/3;align-self:center;justify-self:center;width:8px;height:8px;border:2px solid #19a8ef;border-radius:50%;box-shadow:0 0 0 4px rgba(25,168,239,.08)}
.legacy-sidebar .sidebar-video-menu nav>a span{grid-column:2;font-weight:800;line-height:1.25}
.legacy-sidebar .sidebar-video-menu nav>a small{grid-column:2;color:#7f8d96;font-size:10px;line-height:1.35;letter-spacing:.03em}
.legacy-sidebar .sidebar-video-menu nav>a:hover,.legacy-sidebar .sidebar-video-menu nav>a[aria-current="page"]{transform:translateX(3px);border-color:#225a73!important;background:linear-gradient(90deg,#162a34,#151b1f)!important;color:#28baff!important}
.legacy-sidebar .sidebar-video-menu nav>a[aria-current="page"]:before{background:#19a8ef;box-shadow:0 0 0 5px rgba(25,168,239,.14),0 0 13px #19a8ef}
.legacy-sidebar section:first-child>a{position:relative;display:flex!important;align-items:center;min-height:50px;margin:7px 0 0!important;padding:11px 42px 11px 16px!important;border:1px solid #232c32!important;border-left:1px solid #232c32!important;background:#111619!important;color:#dbe2e6!important;font-weight:700;transition:border-color .2s ease,color .2s ease,transform .2s ease}
.legacy-sidebar section:first-child>a:after{content:"↗";position:absolute;right:16px;color:#19a8ef;font-size:15px}
.legacy-sidebar section:first-child>a:hover{transform:translateX(3px);border-color:#19a8ef!important;color:#fff!important;background:#162029!important}
.sidebar-video-menu summary:focus-visible,.legacy-sidebar section:first-child a:focus-visible{outline:2px solid #19a8ef;outline-offset:2px}
@media(max-width:850px){.legacy-sidebar section:first-child{padding:15px}.legacy-sidebar section:first-child>h2{margin:-15px -15px 14px}.sidebar-video-menu summary{min-height:50px}.legacy-sidebar .sidebar-video-menu nav>a{padding-block:13px!important}}
@media(prefers-reduced-motion:reduce){.sidebar-video-menu,.sidebar-video-menu summary:after,.legacy-sidebar .sidebar-video-menu nav>a,.legacy-sidebar section:first-child>a{transition:none}}