.geometry-lesson svg.diagram {overflow:hidden;}
.geometry-lesson .board {background-image:none;}
.geometry-lesson svg.diagram > use[href="#v-plane"] {display:none;}
.geometry-lesson .textbook-drawing-host {position:relative;}
.geometry-lesson .textbook-zoom-button {position:absolute;top:8px;right:8px;z-index:1;width:36px;height:36px;padding:0;border:1px solid var(--line);border-radius:8px;background:#fff;color:var(--accent);font:600 23px/1 var(--font-body);cursor:pointer;}
.geometry-lesson .textbook-zoom-button:hover {background:#eef4f0;}
.geometry-lesson .textbook-zoom-button:focus-visible {outline:2px solid var(--accent);outline-offset:2px;}
.textbook-drawing-dialog {width:min(1100px,calc(100vw - 24px));max-width:none;padding:18px;border:1px solid var(--line);border-radius:16px;color:var(--ink);background:var(--paper,#fbfaf7);}
.textbook-drawing-dialog::backdrop {background:rgb(20 30 25 / .55);}
.textbook-drawing-dialog header {display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:14px;}
.textbook-drawing-dialog h2 {font:600 21px/1.4 var(--font-display);margin:0;}
.textbook-drawing-actions {display:flex;gap:8px;flex:none;}
.textbook-drawing-actions button {min-width:42px;min-height:42px;padding:8px 12px;border:1px solid var(--line);border-radius:8px;background:#fff;color:var(--accent);font:600 17px/1.4 var(--font-body);cursor:pointer;}
.textbook-drawing-actions button:disabled {opacity:.4;cursor:default;}
.textbook-drawing-viewport {max-height:70dvh;min-height:260px;overflow:auto;background:#fff;border:1px solid var(--line);border-radius:10px;cursor:grab;overscroll-behavior:contain;}
.textbook-drawing-viewport:active {cursor:grabbing;}
.textbook-drawing-viewport > svg {display:block;max-width:none!important;height:auto!important;margin:12px;user-select:none;}
@media(max-width:600px){.textbook-drawing-dialog{padding:12px;}.textbook-drawing-dialog header{align-items:flex-start;flex-direction:column;gap:10px;}.textbook-drawing-dialog h2{font-size:18px;}.textbook-drawing-viewport{max-height:65dvh;}}