*{box-sizing:border-box}html,body{margin:0;height:100%;min-height:460px;background:#f7f9fc;color:#19334f;font-family:"Microsoft YaHei","PingFang SC",Arial,sans-serif}button,input,select{font:inherit}button{cursor:pointer}button:focus-visible,input:focus-visible,select:focus-visible{outline:2px solid #4485d0;outline-offset:2px}[hidden]{display:none!important}.shell{display:flex;flex-direction:column;height:100dvh;min-height:480px}.header{height:68px;flex-shrink:0;display:flex;align-items:center;justify-content:space-between;background:#fff;border-bottom:1px solid #e4eaf1;padding:0 25px;gap:16px;box-shadow:0 1px 7px #17365408;z-index:10}.brand{display:flex;gap:11px;align-items:center;min-width:190px}.brand-symbol{height:39px;width:39px;background:#193d62;color:white;border-radius:12px;display:grid;place-items:center;font-size:23px;font-weight:800;font-family:Georgia,serif}.brand strong{display:block;font-size:15px;letter-spacing:.04em}.brand 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.shell.panel-hidden .editor-panel{display:none}

/* V0.6 compact in-workspace teaching drawer; no extra windows */
#study-compact-toggle{background:#e9f5ef;border-color:#b5dcc8;color:#216d55}
.study-drawer{position:absolute;right:14px;top:75px;bottom:50px;width:min(405px,calc(100% - 28px));z-index:18;border:1px solid #d2e2ed;border-radius:13px;background:#fff;box-shadow:0 15px 45px #1a3a5870;display:flex;flex-direction:column;overflow:hidden}
.study-header{padding:17px 18px 13px;display:flex;align-items:flex-start;justify-content:space-between;border-bottom:1px solid #edf1f5;background:#fafcfe}
.study-header strong{font-size:16px;color:#1e4466}
.study-header p{margin:4px 0 0;font-size:11px;color:#8a9caf}
.study-header button{border:0;background:transparent;font-size:24px;color:#8b9fb0}
.study-tabs{display:flex;gap:7px;padding:10px 14px;border-bottom:1px solid #e8eff5}
.study-tabs button{flex:1;border:1px solid #e1eaf1;background:#f7fafc;color:#668095;padding:9px 4px;border-radius:8px;font-size:12px}
.study-tabs button.active{background:#215b86;border-color:#215b86;color:#fff;font-weight:700}
.study-content{padding:15px 16px;overflow:auto;min-height:0;flex:1;scrollbar-width:thin}
.study-toolbar{display:flex;justify-content:space-between;gap:8px;align-items:center;color:#8293a4;font-size:11px;margin-bottom:12px}
.study-toolbar button{padding:6px 9px;background:#f2f8fc;border:1px solid #deebf4;color:#2d6188;border-radius:7px;font-size:11px}
#study-question-select,.intersection-selectors select{height:40px;width:100%;border-radius:8px;border:1px solid #d5e4ee;padding:7px;background:white;color:#244967;font-size:12px}
.study-question-heading{display:flex;justify-content:space-between;gap:8px;padding:15px 0 5px;font-size:11px;color:#517493}
.study-question-heading strong{color:#1d5a87}
.study-question-text{font-size:15px;font-weight:750;line-height:1.85;color:#1e425f;margin:7px 0 14px}
.question-options{display:grid;gap:9px}
.question-options label{display:flex;align-items:flex-start;gap:9px;padding:10px;border:1px solid #e0e9f0;border-radius:8px;color:#385877;font-size:12px;line-height:1.65;cursor:pointer}
.question-options label:has(input:checked){border-color:#81b3d2;background:#f1f8ff}
.question-options input{accent-color:#2766a2;margin-top:4px}
.study-question-actions{display:flex;gap:8px;margin-top:15px}
.study-question-actions button{flex:1}
.study-guidance{font-size:11px;color:#91a0ae;line-height:1.8;margin:13px 0 0}
.study-feedback{margin-top:12px;border-radius:9px;padding:11px;font-size:12px;line-height:1.8}
.study-feedback p{margin:5px 0 0}
.study-feedback.correct{background:#e8f6ee;color:#2c7253}
.study-feedback.incorrect{background:#fff3ea;color:#98613a}
#study-free-answer{width:100%;height:38px;border:1px solid #d4e0ed;border-radius:7px;padding:8px}
.study-formula-series{display:flex;flex-direction:column;gap:8px;margin-bottom:13px;padding:13px;border:1px solid #dceaf4;border-radius:9px;background:#f7fbfe;overflow-wrap:anywhere}
.study-formula-series strong{font-size:13px;color:#2c5478}
.study-formula-series span{font-size:13px;font-family:"Times New Roman",serif;color:#415f7d}
.formula-detail{border:1px solid #e2eaf1;border-radius:9px;margin:8px 0;background:white;overflow:hidden}
.formula-detail summary{padding:12px;cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:8px;font-size:12px;color:#2b5376}
.formula-detail summary b{font-weight:750;text-align:right;color:#1c6890;overflow-wrap:anywhere}
.formula-detail[open] summary{background:#f5f9fc}
.formula-detail ol{padding:7px 15px 11px 34px;margin:0;color:#627e94;line-height:2;font-size:12px;overflow-wrap:anywhere}
.study-intersection{border-top:1px solid #e3edf5;margin-top:18px;padding-top:15px}
.study-intersection h3{font-size:13px;color:#1e4664;margin:0 0 13px}
.intersection-selectors{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.intersection-selectors select{min-width:0}
.intersection-toggle{margin:13px 0;display:flex;gap:8px;align-items:center;font-size:12px;color:#526f86}
.intersection-toggle input{accent-color:#9951b6}
.intersection-points{padding:10px;background:#f7f1fc;color:#7b4093;font-size:12px;line-height:1.85;border-radius:8px;overflow-wrap:anywhere}
#intersection-result{font-size:12px;color:#698397}
#study-compact-toggle{display:block}
@media(max-width:850px){#study-toggle{display:none}}
@media(max-width:650px){.study-drawer{top:59px;bottom:42px;right:6px;width:calc(100% - 12px)}.study-header{padding:13px 14px}.study-content{padding:12px}.graph-actions button#study-compact-toggle{font-size:10px;padding:0 6px}}