/* 小屏幕保留四个高频入口，并用“更多”承载完整学习路径。 */
.mobile-nav{display:none}
.skip-link{position:fixed;z-index:100;top:9px;left:9px;padding:10px 13px;border-radius:10px;background:#273146;color:#fff;font-size:13px;font-weight:850;text-decoration:none;transform:translateY(-160%);transition:transform .16s}
.skip-link:focus{transform:translateY(0)}
button:focus-visible,label:focus-within,a:focus-visible{outline:3px solid #aaa4f4;outline-offset:2px}
.resume-session{display:grid;grid-template-columns:48px minmax(0,1fr) auto;gap:13px;align-items:center;margin-top:16px;padding:16px 18px;border:1px solid #d8e4db;border-radius:19px;background:linear-gradient(135deg,#eefbf6,#fff 60%,#f2f1ff)}.resume-session>i{display:grid;place-items:center;width:46px;height:46px;border-radius:15px;background:#fff;color:#4d46a8;font-size:24px;font-style:normal}.resume-session span{color:#27806b;font-size:11px;font-weight:850}.resume-session h2{margin:3px 0;color:#465166;font-size:16px}.resume-session p{margin:0;color:#6f7a8d;font-size:12px;line-height:1.55}.resume-session.compact{margin-top:13px;padding:13px 15px}.resume-session.compact h2{font-size:15px}

@media(max-width:930px){
  .shell{grid-template-columns:minmax(0,1fr);min-width:0}
  .main{width:100%;min-width:0;padding-bottom:128px;scroll-padding-bottom:112px}
  .mobile-nav{position:fixed;z-index:20;right:12px;bottom:12px;left:12px;display:grid;grid-template-columns:repeat(5,1fr);gap:4px;padding:7px;border:1px solid #dde1eb;border-radius:18px;background:rgba(255,255,255,.96);box-shadow:0 12px 32px rgba(44,49,84,.17);backdrop-filter:blur(12px)}
  .mobile-nav button,.mobile-more>summary{display:grid;gap:2px;place-items:center;min-height:49px;padding:6px 3px;border:0;border-radius:12px;background:transparent;color:#68758a;font-size:10px;font-weight:850;cursor:pointer;list-style:none}
  .mobile-nav button i,.mobile-more>summary i{font-size:17px;font-style:normal;line-height:1}
  .mobile-nav button.active{background:#f0efff;color:#5c54d6}
  .mobile-more{position:relative;min-width:0}.mobile-more>summary::-webkit-details-marker{display:none}.mobile-more[open]>summary{background:#f0efff;color:#5c54d6}.mobile-more:not([open]) .mobile-more-menu{display:none}
  .mobile-more-menu{position:absolute;right:0;bottom:calc(100% + 12px);display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px;width:min(330px,calc(100vw - 24px));padding:8px;border:1px solid #dde1eb;border-radius:16px;background:rgba(255,255,255,.98);box-shadow:0 14px 34px rgba(44,49,84,.2)}
  .mobile-more-menu button{min-height:58px;padding:7px 5px;background:#f8f8fc}.mobile-more-menu button.active{background:#eceaff}
}

@media(max-width:380px){
  .mobile-nav{right:8px;bottom:8px;left:8px}
  .mobile-nav button,.mobile-more>summary{font-size:9px}.mobile-more-menu{width:calc(100vw - 16px)}
  .resume-session{grid-template-columns:42px minmax(0,1fr)}.resume-session>i{width:40px;height:40px;font-size:21px}.resume-session>button{grid-column:2;justify-self:start}.resume-session p{font-size:11px}
}