/* BuildBefore30 V13 — full-width reading space, true menu hiding, mobile-first. */
.guide-menu[hidden],.menu-reopen[hidden],.toc-panel[hidden],.tools-panel[hidden]{display:none!important}
.guide-menu{height:auto!important;min-height:0!important;position:sticky!important;top:0!important;z-index:60!important}
.guide-menu::before{content:none!important}
.guide-menu .nav-shell{min-height:66px!important}
.guide-menu .nav-link{display:inline-flex!important;align-items:center;gap:8px}
.guide-menu .nav-chevron .bb-collapse-label{font-size:12px!important;transform:none!important}
.guide-menu .nav-chevron .bb-chevron-icon{transform:none!important}
.menu-reopen{position:fixed;top:12px;right:clamp(12px,3vw,30px);z-index:65;display:inline-flex;align-items:center;gap:9px;border:1px solid #387e62;background:#08281f;color:#e5fff2;box-shadow:0 7px 26px #001d1740;padding:10px 14px;border-radius:5px;font:600 12px/1.2 system-ui,sans-serif;cursor:pointer}
.menu-reopen:hover,.menu-reopen:focus-visible{background:#15513d;outline-offset:3px}
body.bb-menu-hidden .book{padding-top:16px!important}
body.bb-menu-hidden .toc-panel{display:none!important}
body.bb-menu-hidden .guide-menu{display:none!important}
body.bb-menu-hidden .sheet:first-child{margin-top:0!important}
.toc-panel{top:76px!important;max-height:calc(100dvh - 92px)!important;z-index:70!important}
.book .sheet,.book.reader .sheet{min-width:0!important;max-width:100%!important;overflow-wrap:anywhere!important}
.book .sheet img{max-width:100%;height:auto}
.book .sheet .bb-real-photo img{height:clamp(190px,28vw,320px)}
@media(max-width:760px){
 .guide-menu .nav-shell{min-height:60px!important;display:grid!important;grid-template-columns:minmax(0,1fr) auto!important;gap:0!important;padding:10px 16px!important}
 .guide-menu .nav-brand{grid-column:1;grid-row:1;font-size:19px!important;min-width:0;overflow:hidden;text-overflow:ellipsis}
 .guide-menu .nav-brand small{display:none!important}
 .guide-menu .nav-chevron{grid-column:2;grid-row:1;min-width:0!important;width:auto!important;min-height:42px!important;border-left:1px solid #295144!important;margin:0!important;padding:0 0 0 12px!important}
 .guide-menu .nav-chevron .bb-collapse-label{display:inline!important;font-size:11px!important}
 .guide-menu .nav-items{grid-column:1/-1;grid-row:2;display:grid!important;grid-template-columns:1fr 1fr!important;width:100%;margin:9px 0 0!important;padding:9px 0 0!important;gap:0!important;border-top:1px solid #295144}
 .guide-menu .nav-link{font-size:12px!important;min-height:44px;justify-content:flex-start;padding:10px 8px!important;white-space:normal!important;border-left:0!important}
 .guide-menu .nav-link:nth-child(2n){border-left:1px solid #295144!important}
 .guide-menu .nav-link:nth-child(n+3){border-top:1px solid #295144!important}
 .toc-panel{top:165px!important;left:10px!important;right:10px!important;width:auto!important;max-height:calc(100dvh - 180px)!important}
 .book{width:100%!important;max-width:100%!important;padding:12px 10px 55px!important}
 .book .sheet,.book.reader .sheet{padding:26px 20px!important;margin-bottom:14px!important;border-radius:10px!important}
 .book .sheet h1{overflow-wrap:anywhere!important;hyphens:auto}
 .book .sheet .mini-grid{grid-template-columns:1fr!important}
 .book .sheet .visual-steps,.book .sheet .visual-equation,.book .sheet .visual-decisions{flex-wrap:wrap!important}
 .book .sheet .visual-steps>span,.book .sheet .visual-equation>span{min-width:90px!important}
 .book .sheet table{max-width:100%;overflow-x:auto!important;display:block!important}
 .book .sheet .bb-real-photo img{height:195px!important}
 .tools-panel{width:min(100vw,100%)!important;max-width:100%!important;overflow-x:hidden!important}
}
@media(max-width:390px){.guide-menu .nav-chevron .bb-collapse-label{font-size:10px!important}.guide-menu .nav-brand{font-size:17px!important}.book .sheet{padding:23px 16px!important}}
@media print{.menu-reopen,.guide-menu{display:none!important}.book{padding:0!important}}