:root{--sidebar:270px;--topbar:72px;--ink:#172033;--muted:#6b768a;--line:#e2e7ef;--panel:#fff;--primary:#2563eb;--primary-soft:#eaf1ff;--bg:#f4f6fa;--radius:16px;--shadow:0 10px 30px rgba(30,41,59,.06)}
*{box-sizing:border-box}html,body{margin:0;min-height:100%;font-family:Inter,system-ui,sans-serif;color:var(--ink);background:var(--bg)}button,input,select,textarea{font:inherit}button{cursor:pointer}.hidden{display:none!important}.mobile-only{display:none!important}
.sidebar{position:fixed;inset:0 auto 0 0;width:var(--sidebar);z-index:60;background:#0d1424;color:#eef4ff;padding:18px 14px;display:flex;flex-direction:column;transition:transform .2s ease,box-shadow .2s ease}.sidebar .icon-btn{background:#162137;border-color:#26334c;color:#dbe7ff}.brand-row{display:flex;align-items:center;gap:11px;padding:1px 5px 18px}.brand-mark{width:39px;height:39px;border-radius:12px;background:#2563eb;display:grid;place-items:center;font-weight:700;font-size:21px}.brand-copy{min-width:0;flex:1}.brand-name{font-weight:700;font-size:15px}.brand-sub{font-size:10px;color:#7f8aa3;margin-top:2px}.sidebar-close{width:32px!important;height:32px!important;font-size:16px!important}.sidebar-actions{display:grid;gap:11px}.btn{border:1px solid transparent;border-radius:10px;padding:9px 13px;font-weight:600;font-size:12px;display:inline-flex;align-items:center;justify-content:center;gap:7px}.btn-primary{background:var(--primary);color:#fff}.btn-primary:hover{background:#1d4ed8}.btn-secondary{background:#fff;border-color:var(--line);color:#334155}.btn-secondary:hover{background:#f8fafc}.btn-danger{background:#fff1f2;border-color:#fecdd3;color:#be123c}.btn-block{width:100%}.search-wrap{display:flex;align-items:center;gap:8px;border:1px solid #26334c;border-radius:10px;padding:0 10px;background:#111a2d;color:#7f8aa3}.search-wrap input{width:100%;border:0;outline:0;background:transparent;color:#eef4ff;padding:10px 0;font-size:12px}.sidebar-section-title{font-size:10px;text-transform:uppercase;letter-spacing:.12em;color:#65738e;font-weight:700;margin:20px 8px 8px}.student-list{display:grid;gap:4px;overflow:auto}.student-item{display:flex;align-items:center;gap:10px;width:100%;border:0;background:transparent;color:#d8e0ef;padding:9px;border-radius:10px;text-align:left}.student-item:hover{background:#131f34}.student-item.active{background:#182744}.avatar{width:34px;height:34px;border-radius:10px;background:#273650;color:#dbeafe;display:grid;place-items:center;font-size:11px;font-weight:700}.avatar.large{width:49px;height:49px;border-radius:14px;background:#eaf1ff;color:#2563eb;font-size:15px}.student-item-text{min-width:0;display:grid}.student-item-text strong{font-size:12px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.student-item-text small{font-size:10px;color:#8490a7;margin-top:3px}.sidebar-footer{margin-top:auto}.sync-card{display:flex;align-items:center;gap:9px;padding:10px;border:1px solid #25304a;border-radius:12px;background:#10182a}.sync-card strong,.sync-card small{display:block}.sync-card strong{font-size:11px}.sync-card small{color:#7f8aa3;font-size:10px;margin-top:2px}.status-dot{width:8px;height:8px;border-radius:50%;background:#22c55e;box-shadow:0 0 0 4px rgba(34,197,94,.12)}.ghost-link{margin-top:10px;width:100%;border:0;background:transparent;color:#71809b;font-size:11px;padding:7px}
.main-area{margin-left:var(--sidebar);width:calc(100% - var(--sidebar));min-height:100vh}.sidebar-collapsed .sidebar{transform:translateX(-100%)}.sidebar-collapsed .main-area{margin-left:0;width:100%}.topbar{height:var(--topbar);display:flex;align-items:center;justify-content:space-between;padding:0 28px;background:rgba(244,246,250,.9);backdrop-filter:blur(12px);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:30}.topbar-left{display:flex;align-items:center;gap:12px}.menu-btn{width:39px;height:39px;border-radius:11px;border:1px solid var(--line);background:#fff;color:#334155;font-size:19px;display:grid;place-items:center}.eyebrow,.label{font-size:11px;text-transform:uppercase;letter-spacing:.08em;font-weight:700;color:#8791a3}.topbar h1{margin:3px 0 0;font-size:20px}.topbar-actions{display:flex;gap:10px}.view{padding:26px}.dashboard-grid{display:grid;grid-template-columns:minmax(280px,.8fr) minmax(420px,1.4fr);gap:20px;max-width:1320px;margin:0 auto}.panel{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow)}.student-summary-panel{min-height:310px;padding:22px}.empty-state{min-height:260px;display:grid;place-items:center;align-content:center;text-align:center;color:var(--muted)}.empty-state h2{color:var(--ink);margin:10px 0 6px;font-size:18px}.empty-state p{margin:0;max-width:260px;font-size:13px;line-height:1.55}.empty-icon{width:54px;height:54px;border-radius:15px;background:var(--primary-soft);display:grid;place-items:center;color:var(--primary);font-size:26px}.profile-row{display:flex;align-items:center;gap:12px}.profile-meta{flex:1}.profile-meta h2{margin:0;font-size:18px}.profile-meta p{margin:5px 0 0;color:var(--muted);font-size:12px}.icon-btn{width:38px;height:38px;border-radius:10px;background:#fff;border:1px solid var(--line);color:var(--ink);display:grid;place-items:center;font-size:18px}.icon-btn:hover{background:#f8fafc}.share-card{margin-top:22px;border-radius:12px;background:#f8fafc;border:1px solid var(--line);padding:14px}.share-url{font-size:12px;margin-top:6px;color:#475569;word-break:break-all;background:#fff;border:1px solid var(--line);border-radius:8px;padding:9px}.share-actions{display:flex;gap:8px;margin-top:10px}.share-actions .btn{font-size:12px;padding:8px 10px}.boards-panel{min-height:500px}.panel-header{padding:20px 22px 14px;display:flex;align-items:center;justify-content:space-between;gap:16px}.panel-header h2{font-size:18px;margin:4px 0 0}.board-list{padding:0 12px 14px}.board-card{display:grid;grid-template-columns:46px minmax(0,1fr) auto;gap:12px;align-items:center;padding:14px 10px;border-top:1px solid #edf0f5;border-radius:10px;cursor:pointer;transition:background .14s ease,transform .14s ease}.board-card:first-child{border-top-color:transparent}.board-card:hover{background:#f8fafc;transform:translateY(-1px)}.board-icon{width:42px;height:42px;border-radius:11px;background:var(--primary-soft);color:var(--primary);display:grid;place-items:center;font-size:19px}.board-card h3{font-size:13px;margin:0 0 5px}.board-card p{margin:0;font-size:11px;color:var(--muted)}.board-card-actions{display:flex;gap:6px}.board-empty{padding:64px 24px;text-align:center;color:var(--muted);font-size:13px}
.board-view{padding:0;height:calc(100vh - var(--topbar));overflow:hidden}.board-topline{height:58px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 18px}.board-title-wrap{display:flex;align-items:center;gap:12px;min-width:0}.board-title-input{border:0;background:transparent;font-size:15px;font-weight:700;color:var(--ink);outline:none;max-width:340px}.save-state{font-size:11px;color:#64748b;white-space:nowrap}.board-top-actions{display:flex;align-items:center;gap:7px}.workspace{position:relative;display:grid;grid-template-columns:78px minmax(0,1fr);height:calc(100% - 58px);background:#fff}.toolrail{background:#fff;border-right:1px solid var(--line);padding:8px 7px;display:flex;flex-direction:column;gap:3px;overflow:auto;z-index:10}.tool-btn{min-height:47px;border:0;background:transparent;border-radius:9px;display:grid;place-items:center;color:#475569;padding:5px 3px}.tool-btn span{font-size:18px;line-height:20px;font-weight:600}.tool-btn small{font-size:8.5px;margin-top:2px}.tool-btn:hover{background:#f1f5f9}.tool-btn.active{background:var(--primary-soft);color:var(--primary)}.tool-btn.math-tool{color:#6d28d9}.tool-btn.math-tool.active{background:#f5f3ff;color:#6d28d9}.canvas-shell{position:relative;overflow:hidden;touch-action:none;background:#fff;contain:layout paint}#whiteboardCanvas{position:absolute;inset:0;width:100%;height:100%;touch-action:none;background:#fff;transform:translateZ(0);backface-visibility:hidden}.student-badge{display:none!important}.selection-hint{display:none!important}.drop-hint{position:absolute;inset:18px;border:2px dashed #60a5fa;border-radius:18px;background:rgba(239,246,255,.93);display:grid;place-items:center;color:#1d4ed8;font-weight:700;font-size:17px;pointer-events:none;z-index:12}.inline-text-editor{position:absolute;min-width:24px;min-height:24px;border:1px solid #93b4f8;border-radius:6px;padding:2px 4px;background:transparent;color:#172033;outline:0;resize:none;overflow:hidden;line-height:1.25;white-space:pre-wrap}.properties{display:none;position:absolute;right:0;top:0;bottom:0;width:262px;background:#fff;border-left:1px solid var(--line);padding:16px;overflow:auto;z-index:15;box-shadow:-10px 0 30px rgba(15,23,42,.08)}.properties.open{display:block}.properties-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:12px}.properties-header strong{font-size:13px}.selected-object-info{background:#f8fafc;border:1px solid var(--line);border-radius:9px;padding:9px 10px;color:#64748b;font-size:10px}.property-group{border-top:1px solid #eef1f5;padding:14px 0}.property-group>label:first-child{font-size:11px;color:#64748b;font-weight:600;display:block;margin-bottom:10px}.color-row{display:grid;grid-template-columns:repeat(6,1fr);gap:8px}.color-swatch{width:27px;height:27px;border-radius:8px;border:2px solid #fff;background:var(--swatch);box-shadow:0 0 0 1px #d9dee7}.color-swatch.selected{box-shadow:0 0 0 2px var(--primary)}input[type=range]{width:100%;accent-color:var(--primary)}select{width:100%;border:1px solid var(--line);background:#fff;border-radius:9px;padding:9px;outline:0}.segmented{display:grid;grid-template-columns:repeat(3,1fr);background:#f1f5f9;border-radius:9px;padding:3px}.segment{border:0;background:transparent;border-radius:7px;padding:7px 5px;font-size:10px;color:#64748b}.segment.active{background:#fff;color:var(--ink);box-shadow:0 1px 3px rgba(0,0,0,.08)}.switch-row{display:flex!important;align-items:center;justify-content:space-between;gap:12px;margin:0!important;color:var(--ink)!important}.switch-row input{width:36px;height:20px;accent-color:var(--primary)}.mobile-toolbar{display:none}
.dialog{border:0;border-radius:16px;padding:0;width:min(460px,calc(100% - 28px));box-shadow:0 28px 80px rgba(15,23,42,.25)}.dialog::backdrop{background:rgba(15,23,42,.4);backdrop-filter:blur(2px)}.compact-dialog{max-width:420px}.dialog-header{padding:18px 20px;border-bottom:1px solid var(--line);display:flex;justify-content:space-between;align-items:center}.dialog-header h2{margin:0;font-size:17px}.dialog-body{padding:20px;display:grid;gap:15px}.dialog-actions{padding:14px 20px;border-top:1px solid var(--line);display:flex;justify-content:flex-end;gap:8px}.dialog-note{margin:0 20px 18px;color:#64748b;font-size:11px;line-height:1.5;background:#f8fafc;border-radius:9px;padding:10px}.field{display:grid;gap:7px}.field span{font-size:11px;font-weight:700;color:#64748b}.field input,.field textarea,.field select{width:100%;border:1px solid #dfe3ea;border-radius:10px;padding:10px 11px;outline:0;background:#fff;resize:vertical}.field input:focus,.field textarea:focus{border-color:#93b4f8;box-shadow:0 0 0 3px rgba(37,99,235,.08)}.two-col-fields{grid-template-columns:1fr 1fr}.two-col-fields .full{grid-column:1/-1}.formula-presets{display:flex;gap:7px;flex-wrap:wrap}.formula-presets button{border:1px solid var(--line);background:#f8fafc;border-radius:8px;padding:7px 9px;font-size:11px}.shape-dialog{max-width:560px}.shape-grid{padding:18px;display:grid;grid-template-columns:repeat(3,1fr);gap:9px}.shape-grid button{border:1px solid var(--line);background:#fff;border-radius:11px;padding:13px 8px;color:#334155;display:grid;place-items:center;gap:6px;font-size:11px}.shape-grid button:hover{background:#f8fafc;border-color:#bfd0ef}.shape-grid span{font-size:24px;color:#2563eb}.shape-grid .shape-icon{width:38px;height:30px;display:block}.shape-grid .shape-icon svg{width:100%;height:100%;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}.segmented.two{grid-template-columns:repeat(2,1fr)}.hidden-prop{display:none}.toast{position:fixed;left:50%;bottom:26px;transform:translateX(-50%);z-index:200;background:#111827;color:#fff;border-radius:10px;padding:10px 14px;font-size:12px;box-shadow:0 8px 30px rgba(0,0,0,.2)}
.student-mode .sidebar-actions,.student-mode .sidebar-section-title,.student-mode .sidebar-footer,.student-mode .student-list{display:none}.student-mode .sidebar{width:0;padding:0;overflow:hidden}.student-mode .main-area{margin-left:0;width:100%}.student-mode #sidebarToggle{display:none}
@media(max-width:1050px){.dashboard-grid{grid-template-columns:1fr}.workspace{grid-template-columns:74px minmax(0,1fr)}}
@media(max-width:900px){:root{--topbar:64px}.mobile-only{display:grid!important}.sidebar{width:280px;box-shadow:20px 0 50px rgba(0,0,0,.22)}.main-area{margin-left:0;width:100%}.sidebar:not(.open){transform:translateX(-100%);box-shadow:none}.sidebar.open{transform:translateX(0)}.sidebar-collapsed .sidebar.open{transform:translateX(0)}.topbar{padding:0 12px}.topbar .btn{font-size:11px;padding:8px 9px}.view{padding:14px}.dashboard-grid{gap:12px}.student-summary-panel{min-height:230px;padding:16px}.boards-panel{min-height:420px}.panel-header{padding:16px 15px 10px}.board-view{padding:0;height:calc(100vh - var(--topbar));padding-bottom:62px}.board-topline{height:52px;padding:0 9px}.board-title-input{max-width:165px}.save-state{display:none}.board-top-actions .btn{display:none}.board-top-actions .icon-btn{width:34px;height:34px}.workspace{height:calc(100% - 52px);grid-template-columns:1fr;background:#fff}.toolrail{display:none;position:absolute;left:8px;right:8px;bottom:70px;top:auto;z-index:28;background:#fff;border:1px solid var(--line);border-radius:14px;padding:8px;box-shadow:0 18px 50px rgba(15,23,42,.18);grid-template-columns:repeat(5,minmax(52px,1fr));max-height:290px;overflow:auto}.toolrail.open{display:grid}.toolrail .tool-btn{min-height:54px}.properties{display:none}.properties.open{display:block;width:min(310px,88vw)}.mobile-toolbar{display:grid;grid-template-columns:repeat(6,1fr);position:absolute;left:0;right:0;bottom:0;height:62px;background:#fff;border-top:1px solid var(--line);z-index:25;padding-bottom:env(safe-area-inset-bottom)}.mobile-tool{border:0;background:#fff;color:#64748b;display:grid;place-items:center;align-content:center;font-size:17px}.mobile-tool small{display:block;font-size:8px;margin-top:3px}.mobile-tool.active{color:var(--primary);background:var(--primary-soft)}.board-card{grid-template-columns:40px minmax(0,1fr) auto;padding:12px 5px}.topbar-actions #studentPortalBtn{display:none}.share-actions{flex-wrap:wrap}.dialog{margin:auto}.two-col-fields{grid-template-columns:1fr 1fr}.shape-grid{grid-template-columns:repeat(2,1fr)}.canvas-shell{min-width:0}.student-badge{top:8px;right:8px}.selection-hint{display:none}.color-row{grid-template-columns:repeat(6,1fr)}}

/* v6 interaction menus and math preview */
.save-state:empty{display:none}
.tool-menu-wrap{display:block}.tool-menu-wrap>.tool-btn{width:100%}
.tool-flyout{position:fixed;z-index:150;display:none;flex-direction:column;min-width:142px;padding:6px;background:#fff;border:1px solid var(--line);border-radius:10px;box-shadow:0 14px 36px rgba(15,23,42,.16)}
.tool-flyout.open,.tool-flyout.mobile-open{display:flex}
.tool-flyout button{border:0;background:transparent;text-align:left;padding:9px 10px;border-radius:7px;color:#334155;font-size:11px;white-space:nowrap}
.tool-flyout button:hover{background:#f1f5f9}
.tool-flyout button.active{background:var(--primary-soft);color:var(--primary);font-weight:700}
.formula-help{font-size:11px;line-height:1.55;color:#64748b;background:#f8fafc;border:1px solid var(--line);border-radius:9px;padding:10px}
.formula-help code{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;background:#eef2f7;padding:1px 4px;border-radius:4px;color:#334155}
.formula-preview-wrap{border:1px solid var(--line);border-radius:10px;background:#fff;padding:9px 10px;overflow:hidden}
.formula-preview-wrap>span{display:block;font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:.07em;color:#94a3b8;margin-bottom:4px}
.formula-preview-wrap canvas{display:block;max-width:100%;height:120px}
.shape-icon{width:36px;height:30px!important;display:grid;place-items:center}
.shape-icon svg{width:36px;height:30px;fill:none;stroke:currentColor;stroke-width:1.6;stroke-linejoin:round;stroke-linecap:round}
.body-note{margin:0!important}
@media(max-width:900px){
  .mobile-toolbar{grid-template-columns:repeat(7,1fr)}
  .tool-flyout{display:none!important}
  .tool-flyout.mobile-open{display:flex!important;left:50%!important;top:auto!important;bottom:72px!important;transform:translateX(-50%)}
}

  
.zoom-btn{min-width:54px;height:34px;border:1px solid var(--line);border-radius:9px;background:#fff;color:#475569;font-size:11px;font-weight:700;padding:0 8px}.zoom-btn:hover{background:#f8fafc;color:#1d4ed8}
.tool-svg{width:23px;height:23px;display:grid;place-items:center}.tool-svg svg{width:23px;height:23px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}.cursor-icon svg{fill:currentColor;stroke:currentColor;stroke-width:1}.pen-icon,.marker-icon{transform:scaleX(-1)}
.pdf-dialog{width:min(620px,calc(100% - 28px))}.pdf-select-row{display:flex;gap:8px}.pdf-page-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(82px,1fr));gap:8px;max-height:360px;overflow:auto;padding:2px}.pdf-page-option{display:flex;align-items:center;gap:7px;border:1px solid var(--line);border-radius:9px;padding:9px;background:#fff;font-size:11px}.pdf-page-option:has(input:checked){border-color:#93b4f8;background:#eff6ff}.pdf-page-option input{accent-color:var(--primary)}


/* v8 editor refinements */
body.sidebar-open #sidebarToggle{position:fixed;left:calc(14px - var(--sidebar));top:16px;z-index:85;background:#162137;color:#fff;border-color:#26334c}
body.sidebar-open .brand-row{padding-left:50px}
.geogebra-layer{position:absolute;inset:0;pointer-events:none;z-index:4;overflow:visible}
.geogebra-object{position:absolute;background:#fff;border:1px solid #cbd5e1;box-shadow:0 4px 18px rgba(15,23,42,.09);overflow:hidden;transform-origin:center center;pointer-events:none}
.geogebra-object.interactive{pointer-events:auto;box-shadow:0 0 0 2px #2563eb,0 8px 24px rgba(15,23,42,.15)}
.geogebra-object .ggb-host{width:100%;height:100%}
.geogebra-object .ggb-placeholder{width:100%;height:100%;display:grid;place-items:center;align-content:center;gap:7px;background:linear-gradient(135deg,#fff,#f8fafc);color:#475569;font-size:12px;text-align:center;padding:16px}
.geogebra-object .ggb-placeholder strong{font-size:18px;color:#6d28d9}
.pdf-page-option{display:grid;grid-template-columns:22px 1fr;align-items:start;gap:7px;padding:8px}.pdf-page-option img{grid-column:1/-1;width:100%;aspect-ratio:3/4;object-fit:contain;background:#f8fafc;border:1px solid #e2e8f0;border-radius:6px}.pdf-page-option .pdf-page-label{font-size:10px;color:#475569;font-weight:700}.pdf-page-list{grid-template-columns:repeat(auto-fill,minmax(120px,1fr));max-height:460px}
.rotate-hint{font-size:10px;color:#64748b}
@media(max-width:900px){body.sidebar-open #sidebarToggle{left:12px;top:12px}.sidebar .brand-row{padding-left:48px}.geogebra-object{touch-action:auto}}
body.sidebar-open .topbar{z-index:80}

/* v9 interaction refinements */
body.board-active .main-area{margin-left:0;width:100%}
body.board-active .sidebar{box-shadow:18px 0 42px rgba(15,23,42,.20)}
body.board-active.sidebar-collapsed .sidebar{transform:translateX(-100%);box-shadow:none}
body.sidebar-open #sidebarToggle{position:fixed;left:14px;top:16px;z-index:95;background:#162137;color:#fff;border-color:#26334c}
body.sidebar-open .brand-row{padding-left:50px}
.tool-cursor-overlay{position:absolute;left:0;top:0;z-index:24;pointer-events:none;transform:translate3d(0,0,0) translate(-50%,-50%);will-change:transform;width,height;border-radius:50%;box-sizing:border-box}
.tool-cursor-overlay.pen{border:1px solid rgba(255,255,255,.9)}
.tool-cursor-overlay.marker{border:1px solid rgba(255,255,255,.65)}
.tool-cursor-overlay.eraser{background:rgba(255,255,255,.12);border:1.5px solid #334155;box-shadow:0 0 0 1px rgba(255,255,255,.75)}
@media(max-width:900px){body.sidebar-open #sidebarToggle{left:12px;top:12px}}
body.sidebar-open #sidebarToggle{left:28px}
@media(max-width:900px){body.sidebar-open #sidebarToggle{left:12px}}


.fraction-quick-controls{position:absolute;z-index:24;transform:translateY(-50%);display:grid;gap:6px;background:rgba(255,255,255,.96);border:1px solid #dbe3ef;border-radius:12px;padding:7px;box-shadow:0 8px 24px rgba(15,23,42,.14);font-size:10px;user-select:none}.fraction-quick-row{display:grid;grid-template-columns:24px 38px 24px;align-items:center;gap:4px}.fraction-quick-row>span{text-align:center;font-weight:700;color:#475569}.fraction-quick-row button{width:24px;height:24px;border:1px solid #dbe3ef;border-radius:7px;background:#fff;color:#1d4ed8;font-weight:800;display:grid;place-items:center;padding:0}.fraction-quick-row button:hover{background:#eff6ff}.snap-note{color:#f43f5e}


/* v11 performance and interaction refinements */
.live-drawing-layer{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;z-index:6;transform:translateZ(0);backface-visibility:hidden}
.tree-probability-layer{position:absolute;inset:0;pointer-events:none;z-index:23}
.tree-probability-input{position:absolute;transform:translate(-50%,-50%);width:58px;height:25px;border:1px solid #cbd5e1;border-radius:7px;background:rgba(255,255,255,.96);padding:2px 6px;font-size:11px;text-align:center;color:#334155;outline:none;pointer-events:auto;box-shadow:0 2px 8px rgba(15,23,42,.08)}
.tree-probability-input:focus{border-color:#60a5fa;box-shadow:0 0 0 2px rgba(37,99,235,.12)}
body:not(.board-active) #sidebarToggle{display:none}
body:not(.board-active) .sidebar{transform:none!important}
body:not(.board-active) .main-area{margin-left:var(--sidebar);width:calc(100% - var(--sidebar))}
body.board-active .sidebar{z-index:100}
body.board-active.sidebar-open .topbar{z-index:30}
body.board-active.sidebar-open #sidebarToggle{position:fixed;left:14px;top:16px;z-index:110;background:#162137;color:#fff;border-color:#26334c}
body.board-active.sidebar-open .brand-row{padding-left:50px}
@media(max-width:900px){body:not(.board-active) #sidebarToggle{display:none}body:not(.board-active) .sidebar{transform:none!important;width:280px}body:not(.board-active) .main-area{margin-left:280px;width:calc(100% - 280px)}body.board-active.sidebar-open #sidebarToggle{left:12px;top:12px}}

/* v14 interaction fixes */
.tree-label-input{position:absolute;transform:translate(-50%,-50%);width:104px;height:25px;border:1px solid #cbd5e1;border-radius:7px;background:rgba(255,255,255,.97);padding:2px 7px;font-size:11px;text-align:left;color:#334155;outline:none;pointer-events:auto;box-shadow:0 2px 8px rgba(15,23,42,.08)}
.tree-label-input:focus{border-color:#60a5fa;box-shadow:0 0 0 2px rgba(37,99,235,.12)}
body.board-active .sidebar{z-index:1000!important}
body.board-active.sidebar-open .sidebar{transform:translateX(0)!important}
body.board-active.sidebar-open #sidebarToggle{display:grid!important;position:fixed!important;left:14px!important;top:16px!important;z-index:1100!important;transform:none!important;background:#162137!important;color:#fff!important;border-color:#26334c!important}
body.board-active.sidebar-open .brand-row{padding-left:50px!important}
@media(max-width:900px){body.board-active.sidebar-open #sidebarToggle{left:12px!important;top:12px!important}}

/* v15 dashboard, table editor and board controls */
#sidebarToggle{display:none!important}
body.board-active .sidebar{transform:translateX(-100%)!important;box-shadow:none!important}
body.board-active .main-area{margin-left:0!important;width:100%!important}
body:not(.board-active) .sidebar{transform:none!important}
body:not(.board-active) .main-area{margin-left:var(--sidebar)!important;width:calc(100% - var(--sidebar))!important}
.dashboard-grid{display:grid!important;grid-template-columns:1fr!important;gap:14px!important;max-width:1500px!important}
.student-summary-panel{min-height:0!important;padding:14px 18px!important}
.student-summary-panel .profile-row{min-height:46px}
.student-summary-panel .avatar.large{width:40px;height:40px;border-radius:11px;font-size:12px}
.student-summary-panel .profile-meta h2{font-size:16px}
.student-summary-panel .profile-meta p{margin-top:2px;font-size:10px}
.student-summary-panel .share-card{margin:10px 0 0!important;padding:9px 10px!important;display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:end;gap:9px;background:#fbfcfe}
.student-summary-panel .share-card .label{font-size:9px}
.student-summary-panel .share-url{margin-top:3px;padding:6px 8px;font-size:10px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.student-summary-panel .share-actions{margin:0!important;flex-wrap:nowrap!important}
.student-summary-panel .share-actions .btn{padding:7px 9px!important;font-size:10px!important}
.boards-panel{min-height:420px!important}
.board-list{display:grid!important;grid-template-columns:repeat(5,minmax(0,1fr));gap:14px!important;padding:0 18px 20px!important}
.board-card{position:relative!important;display:block!important;padding:0!important;border:1px solid #e4e9f1!important;border-radius:14px!important;overflow:hidden;background:#fff!important;min-width:0;transform:none!important}
.board-card:hover{border-color:#b9c9e6!important;box-shadow:0 9px 26px rgba(15,23,42,.08);transform:translateY(-2px)!important}
.board-preview-wrap{aspect-ratio:16/9;background:#f8fafc;border-bottom:1px solid #e8edf4;overflow:hidden}
.board-preview{display:block;width:100%;height:100%;background:#fff}
.board-card-meta{padding:10px 11px 12px;display:grid;grid-template-columns:1fr auto;gap:3px 8px;align-items:center}
.board-card-meta h3{grid-column:1/-1;margin:0 0 3px!important;font-size:12px!important;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.board-card-meta p{margin:0!important;font-size:9.5px!important;color:#64748b}
.board-card-meta strong{font-size:10px;color:#334155;font-weight:700}
.board-card>.board-delete{position:absolute;right:7px;top:7px;width:29px;height:29px;background:rgba(255,255,255,.92);backdrop-filter:blur(5px);font-size:16px}
.board-bg-controls{display:grid;grid-template-columns:repeat(3,auto)!important;width:auto!important;padding:2px!important;gap:1px;min-width:150px}
.board-bg-controls .segment{padding:6px 8px!important;font-size:9px!important;white-space:nowrap}
.table-quick-control{position:absolute;z-index:25;transform:translate(0,-50%);pointer-events:auto}
.table-quick-control button{width:30px;height:30px;border:1px solid #cbd5e1;border-radius:9px;background:#fff;color:#2563eb;font-weight:800;box-shadow:0 5px 16px rgba(15,23,42,.13)}
.table-quick-control button.active{background:#2563eb;color:#fff;border-color:#2563eb}
.table-cell-editor{position:absolute;z-index:28;transform:translate(-50%,-50%);height:30px;border:2px solid #2563eb;border-radius:7px;background:#fff;padding:3px 7px;color:#172033;outline:none;box-shadow:0 6px 18px rgba(15,23,42,.15);text-align:left}
.tree-label-input{text-align:center!important;border-radius:9px!important;font-weight:600}
.tree-probability-input{width:64px!important}
.fraction-quick-controls{z-index:26!important}
@media(max-width:1250px){.board-list{grid-template-columns:repeat(4,minmax(0,1fr))!important}}
@media(max-width:1000px){.board-list{grid-template-columns:repeat(3,minmax(0,1fr))!important}.board-bg-controls{min-width:132px}.board-bg-controls .segment{padding:6px 6px!important}}
@media(max-width:900px){body:not(.board-active) .sidebar{width:250px!important}body:not(.board-active) .main-area{margin-left:250px!important;width:calc(100% - 250px)!important}.board-list{grid-template-columns:repeat(2,minmax(0,1fr))!important}.student-summary-panel .share-card{grid-template-columns:1fr}.student-summary-panel .share-actions{justify-content:flex-start}.board-bg-controls{display:none}}
@media(max-width:620px){body:not(.board-active) .sidebar{width:210px!important}body:not(.board-active) .main-area{margin-left:210px!important;width:calc(100% - 210px)!important}.board-list{grid-template-columns:1fr!important}}
body.student-mode:not(.board-active) .main-area{margin-left:0!important;width:100%!important}
.student-summary-panel #studentSummary:not(.hidden){display:grid;grid-template-columns:minmax(210px,.55fr) minmax(420px,1.45fr);align-items:center;gap:16px}
.student-summary-panel #studentSummary .share-card{margin:0!important}
@media(max-width:1050px){.student-summary-panel #studentSummary:not(.hidden){grid-template-columns:1fr}.student-summary-panel #studentSummary .share-card{margin-top:8px!important}}
/* v16 refinements */
.board-title-input{display:none!important}
.board-card-meta{grid-template-columns:1fr auto;min-height:46px}
.board-card-meta p{font-size:10px!important;font-weight:600;color:#475569!important}
#propertiesToggleBtn{display:none!important}

.pen-icon svg{transform:scaleX(-1);transform-origin:center}
.table-insert-control{position:absolute;z-index:32;transform:translate(-50%,-50%);pointer-events:auto}
.table-insert-control button{width:25px;height:25px;border-radius:50%;border:2px solid #fff;background:#2563eb;color:#fff;font-size:18px;line-height:19px;font-weight:700;display:grid;place-items:center;box-shadow:0 3px 12px rgba(37,99,235,.28);padding:0}
.table-insert-control button:hover{transform:scale(1.08);background:#1d4ed8}
\n\n/* v22 Cloud */\n.cloud-gate{position:fixed;inset:0;z-index:1000;background:linear-gradient(145deg,#f4f6fa,#eaf1ff);display:grid;place-items:center;padding:24px}\n.cloud-gate-card{width:min(430px,100%);background:#fff;border:1px solid #dfe5ef;border-radius:20px;box-shadow:0 28px 80px rgba(15,23,42,.16);padding:30px}\n.cloud-gate-mark{width:52px;height:52px;border-radius:15px;background:#2563eb;color:#fff;display:grid;place-items:center;font-weight:800;font-size:28px;margin-bottom:18px}\n.cloud-gate-card h1{font-size:24px;margin:0 0 8px}.cloud-gate-card>p{font-size:13px;line-height:1.6;color:#64748b;margin:0 0 20px}\n.cloud-auth-form{display:grid;gap:12px}.cloud-auth-form .btn{min-height:42px}.cloud-gate-message{min-height:20px;margin-top:14px;font-size:11px;line-height:1.55;color:#64748b}\n.cloud-warning .status-dot{background:#f59e0b;box-shadow:0 0 0 4px rgba(245,158,11,.14)}\n.student-mode #cloudLogoutBtn{display:none!important}\n

/* v24: Sidebar exists only in teacher overview. Fixed toggle never moves. */
#sidebarToggle{display:none!important}
body:not(.student-mode):not(.board-active) #sidebarToggle{
  display:grid!important;position:fixed!important;left:14px!important;top:16px!important;
  z-index:1300!important;transform:none!important;background:#fff!important;color:#334155!important;border-color:var(--line)!important
}
body:not(.student-mode):not(.board-active).sidebar-open #sidebarToggle{
  left:14px!important;top:16px!important;background:#162137!important;color:#fff!important;border-color:#26334c!important
}
body:not(.student-mode):not(.board-active) .sidebar{
  display:flex!important;visibility:visible!important;pointer-events:none!important;transform:translateX(-100%)!important;
  box-shadow:none!important;z-index:1200!important
}
body:not(.student-mode):not(.board-active).sidebar-open .sidebar{
  pointer-events:auto!important;transform:translateX(0)!important;box-shadow:18px 0 42px rgba(15,23,42,.20)!important
}
body:not(.student-mode):not(.board-active).sidebar-open .brand-row{padding-left:50px!important}
body:not(.student-mode):not(.board-active) .main-area{margin-left:0!important;width:100%!important}
body:not(.student-mode):not(.board-active) .topbar-left{padding-left:48px}
body.board-active .sidebar,body.student-mode .sidebar{
  display:none!important;visibility:hidden!important;pointer-events:none!important;transform:translateX(-100%)!important;box-shadow:none!important
}
body.board-active #sidebarToggle,body.student-mode #sidebarToggle{display:none!important}
body.board-active .main-area,body.student-mode .main-area{margin-left:0!important;width:100%!important}
body.board-active.sidebar-open,body.student-mode.sidebar-open{--sidebar:270px}
@media(max-width:900px){
  body:not(.student-mode):not(.board-active) #sidebarToggle,body:not(.student-mode):not(.board-active).sidebar-open #sidebarToggle{left:12px!important;top:12px!important}
  body:not(.student-mode):not(.board-active) .sidebar{width:280px!important}
  body:not(.student-mode):not(.board-active) .main-area{margin-left:0!important;width:100%!important}
  body:not(.student-mode):not(.board-active) .topbar-left{padding-left:48px}
}