.theory-layout{grid-template-columns:150px minmax(0,1fr);align-items:start;gap:40px;max-width:1100px;margin:0 auto;padding:30px 24px 60px;display:grid}@media (width<=768px){.theory-layout{grid-template-columns:minmax(0,1fr)}}@media (width>=769px){.theory-layout{grid-template-columns:210px minmax(0,1fr);gap:28px;max-width:1160px;margin:0}.topbar-inner,.topbar-crumb{max-width:1160px;margin:0}}.theory-main{min-width:0}.theory-rail{flex-direction:column;align-self:start;max-height:calc(100vh - 40px);display:flex;position:sticky;top:20px}.rail-back{min-height:40px;font-family:var(--sans);color:var(--interactive);border-bottom:1px solid var(--border);flex-shrink:0;align-items:center;margin-bottom:8px;padding-bottom:10px;font-size:12.5px;font-weight:600;text-decoration:none;display:flex}.rail-back:hover{text-decoration:underline}.rail-title{font-family:var(--mono);letter-spacing:.09em;color:var(--muted);flex-shrink:0;margin-bottom:4px;padding:0 8px;font-size:10px}.rail-index{overscroll-behavior:contain;flex:1;min-height:0;overflow-y:auto}.rail-group{font-family:var(--mono);letter-spacing:.09em;text-transform:uppercase;color:var(--muted);margin:16px 0 4px;padding:0 8px;font-size:9.5px}.rail-group:first-child{margin-top:2px}.theory-rail .rail-item{border-radius:0 var(--r-sm) var(--r-sm) 0;border-left:2px solid #0000;grid-template-columns:auto minmax(0,1fr);align-items:start;gap:7px;min-height:40px;padding:7px 8px;line-height:1.35;text-decoration:none;display:grid}.theory-rail .rail-item .rail-num{font-family:var(--mono);color:var(--interactive);white-space:nowrap;word-spacing:-3px;padding-top:1.5px;font-size:10.5px}.theory-rail .rail-item .rail-name{font-family:var(--sans);color:var(--body-soft);overflow-wrap:anywhere;font-size:11.5px}.theory-rail .rail-item:hover{background:var(--surface-alt)}.theory-rail .rail-item:hover .rail-name{color:var(--ink)}.theory-rail .rail-item.active{border-left-color:var(--ink);background:var(--interactive-bg)}.theory-rail .rail-item.active .rail-name{color:var(--ink);font-weight:600}@media (width<=768px){.theory-rail{display:none}}.chip-rail{display:none}@media (width<=768px){.chip-rail{background:var(--white);border-bottom:1px solid var(--border);z-index:10;align-items:center;gap:10px;padding:8px 16px 8px 68px;display:flex;position:sticky;top:0}.crumb-back{display:none!important}.chip-back{min-height:40px;font-family:var(--sans);color:var(--interactive);border-right:1px solid var(--border);flex-shrink:0;align-items:center;padding-right:10px;font-size:12px;font-weight:600;text-decoration:none;display:inline-flex}.chip-scroll{-webkit-overflow-scrolling:touch;flex:1;gap:8px;min-width:0;display:flex;overflow-x:auto}.chip-rail .chip{min-width:40px;min-height:40px;font-family:var(--mono);border:1px solid var(--border);color:var(--body-soft);white-space:nowrap;word-spacing:-3px;border-radius:999px;flex-shrink:0;justify-content:center;align-items:center;padding:0 12px;font-size:11px;text-decoration:none;display:inline-flex}}.theory-main h1{font-family:var(--serif);color:var(--ink);margin-bottom:20px;font-size:27px;font-weight:700}.def-card{border:1px solid var(--border);border-radius:var(--r-lg);background:var(--white);margin-bottom:14px;padding:0;scroll-margin-top:20px}@media (width<=768px){.def-card{scroll-margin-top:70px}}.def-card summary{cursor:pointer;font-family:var(--serif);color:var(--ink);align-items:baseline;gap:8px;padding:16px 20px;font-size:15px;font-weight:600;list-style:none;display:flex}.def-card summary::-webkit-details-marker{display:none}.def-card .rn{font-family:var(--mono);color:var(--interactive);word-spacing:-3px;flex-shrink:0;font-size:12px}.def-card .def-body{padding:0 20px 18px}.def-card .def-body p{font-family:var(--sans);color:var(--body);margin-bottom:10px;font-size:13.5px;line-height:1.7}.def-card .def-body p:last-child{margin-bottom:0}.def-card .def-body ul,.def-card .def-body ol{margin:8px 0 10px 22px}.def-card .def-body li{font-family:var(--sans);color:var(--body);margin-bottom:4px;font-size:13px;line-height:1.65}.def-body .fml{background:var(--surface);border:1px solid var(--border);border-radius:var(--r-lg);text-align:center;color:var(--ink);max-width:100%;margin:10px 0;padding:14px 18px;overflow:auto hidden}.def-body :where(p,li){overflow-wrap:break-word}.def-body .fig{border:1px solid var(--border);border-radius:var(--r-lg);max-width:100%;margin:14px 0;display:inline-block;overflow:hidden}.def-body .fig img{max-width:100%;height:auto;display:block}.def-body .fig .stage{position:relative}.def-body .fig .fig-caption{background:var(--surface-alt);border-top:1px solid var(--border);font-family:var(--sans);color:var(--body-soft);justify-content:space-between;align-items:center;gap:10px;padding:8px 12px;font-size:11.5px;display:flex}.def-body .fig .toggle{color:var(--interactive);font-family:var(--sans);cursor:pointer;background:0 0;border:none;flex-shrink:0;justify-content:center;align-items:center;min-height:40px;padding:8px 12px;font-size:11.5px;font-weight:600;display:inline-flex}.def-body .fig .toggle:disabled{opacity:.55;cursor:default}.def-body .fig .stage .canvas3d{background:#f7f4ef;position:absolute;inset:0}.def-body .fig .rotate-hint{font-family:var(--sans);color:var(--muted);text-align:center;padding:6px 0 2px;font-size:11px}.group-head{font-family:var(--mono);letter-spacing:.09em;text-transform:uppercase;color:var(--muted);border-top:1px solid var(--border);margin:26px 0 10px;padding-top:10px;font-size:11px}.group-head:first-child{border-top:none;margin-top:0;padding-top:0}