/* M03K06 · Boundary-defined modes */
.boundary-chapter{padding-top:72px;scroll-margin-top:calc(var(--header-h) + 24px)}
.k06-header{display:grid;grid-template-columns:minmax(0,1.45fr) minmax(280px,.55fr);gap:28px;align-items:end}.k06-header h1{margin:9px 0 14px;font-size:clamp(3.2rem,7vw,6.7rem);line-height:.91;letter-spacing:-.062em}.k06-header .lead{max-width:880px;color:var(--muted);font-size:1.08rem}.k06-index{padding:22px;border:1px solid var(--line);border-radius:var(--radius-sm);background:var(--panel)}.k06-index>span,.boundary-card>span,.boundary-family-card>span,.boundary-limit-grid article>span{display:block;color:var(--accent);font-size:.72rem;font-weight:800;letter-spacing:.08em;text-transform:uppercase}.k06-index strong{display:block;margin:7px 0 8px;font-size:1.04rem}.k06-index p{margin:0;color:var(--muted);font-size:.9rem}
.boundary-conditions,.boundary-families,.boundary-limits{padding-top:72px}.boundary-condition-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}.boundary-card,.boundary-family-card,.boundary-limit-grid article{padding:22px;border:1px solid var(--line);border-radius:var(--radius-sm);background:var(--panel)}.boundary-card.key{border-color:var(--line-strong);background:linear-gradient(150deg,var(--panel-solid),var(--panel))}.boundary-card strong,.boundary-family-card strong,.boundary-limit-grid strong{display:block;margin:9px 0;font-size:1.2rem}.boundary-card p,.boundary-family-card p,.boundary-limit-grid p{margin:0;color:var(--muted);font-size:.9rem}.boundary-card .equation{margin:14px 0}
.boundary-selection{margin-top:72px;padding:72px 0;background:var(--panel-solid)}.boundary-family-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.boundary-family-card.key{border-color:var(--accent)}.boundary-family-card .equation{margin:12px 0}.boundary-family-card small{display:block;margin-top:10px;color:var(--muted);font-size:.78rem}.boundary-note{margin-top:14px;padding:16px 18px;border-left:2px solid var(--warm);background:color-mix(in srgb,var(--warm) 6%,transparent);color:var(--muted);font-size:.9rem}.boundary-note strong{color:var(--text)}
.boundary-lab-section{padding:82px 0}.boundary-lab-shell{display:grid;grid-template-columns:minmax(260px,320px) minmax(0,1fr);gap:16px;align-items:start}.boundary-controls{position:sticky;top:calc(var(--header-h) + 18px);display:grid;gap:14px;padding:20px;border:1px solid var(--line);border-radius:var(--radius-sm);background:var(--panel)}.boundary-preset-row{display:grid;grid-template-columns:1fr 1fr;gap:8px}.boundary-preset-row button{min-height:40px;padding:8px 9px;border:1px solid var(--line);border-radius:10px;background:var(--panel-solid);color:var(--text);font:inherit;font-size:.76rem;cursor:pointer}.boundary-preset-row button:hover,.boundary-preset-row button:focus-visible,.boundary-preset-row button.is-active{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 9%,var(--panel-solid))}.boundary-control-group{display:grid;gap:8px}.boundary-control-label{display:flex;align-items:baseline;justify-content:space-between;gap:12px;font-size:.82rem}.boundary-control-label label{color:var(--muted)}.boundary-control-label output{font-weight:800}.boundary-control-group input[type="range"]{width:100%;accent-color:var(--accent)}.boundary-range-meta{display:flex;justify-content:space-between;color:var(--muted);font-size:.69rem}.boundary-actions{display:grid;grid-template-columns:1fr 1fr;gap:8px}.boundary-actions button{min-height:40px;border:1px solid var(--line);border-radius:10px;background:var(--panel-solid);color:var(--text);cursor:pointer}.boundary-actions button:hover,.boundary-actions button:focus-visible{border-color:var(--line-strong)}.boundary-actions .boundary-snap{grid-column:1/-1}.boundary-status{grid-column:1/-1;display:flex;align-items:center;gap:8px;color:var(--muted);font-size:.8rem}.boundary-status i{width:8px;height:8px;border-radius:50%;background:var(--accent-3);box-shadow:0 0 12px color-mix(in srgb,var(--accent-3) 70%,transparent)}.boundary-stage{min-width:0;display:grid;gap:14px}.boundary-panel{overflow:hidden;border:1px solid var(--line);border-radius:var(--radius-sm);background:var(--panel)}.boundary-panel-head{display:flex;justify-content:space-between;gap:18px;align-items:center;padding:17px 20px;border-bottom:1px solid var(--line)}.boundary-panel-head span,.boundary-head-readout span{display:block;color:var(--muted);font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;font-weight:800}.boundary-panel-head strong{display:block;margin-top:4px}.boundary-head-readout{text-align:right}.boundary-field-svg{display:block;width:100%;min-height:360px;background:linear-gradient(180deg,color-mix(in srgb,var(--panel-solid) 78%,transparent),transparent)}.boundary-axis,.boundary-grid-line{stroke:var(--line-strong);stroke-width:1}.boundary-grid-line{opacity:.48}.boundary-candidate{fill:none;stroke:var(--accent);stroke-width:4;stroke-linecap:round;stroke-linejoin:round}.boundary-instant{fill:none;stroke:var(--accent-2);stroke-width:2.5;stroke-linecap:round;stroke-linejoin:round}.boundary-envelope{fill:none;stroke:var(--muted);stroke-width:1.4;stroke-dasharray:7 7;opacity:.55}.boundary-wall{stroke:var(--text);stroke-width:3}.boundary-wall-hatch{stroke:var(--muted);stroke-width:1.5}.boundary-end-dot{fill:var(--panel-solid);stroke:var(--warm);stroke-width:3}.boundary-tangent{stroke:var(--warm);stroke-width:3;stroke-linecap:round}.boundary-end-label,.boundary-axis-label,.boundary-mode-label{fill:var(--muted);font-size:13px;font-weight:700}.boundary-mode-label{fill:var(--text);font-size:14px}.boundary-legend{display:flex;flex-wrap:wrap;gap:15px;padding:13px 18px;border-top:1px solid var(--line);color:var(--muted);font-size:.75rem}.boundary-legend span{display:inline-flex;align-items:center;gap:7px}.boundary-legend i{width:20px;height:3px;border-radius:3px;background:var(--accent)}.boundary-legend .instant i{background:var(--accent-2)}.boundary-legend .condition i{background:var(--warm)}
.boundary-telemetry{display:grid;grid-template-columns:repeat(5,1fr);border-top:1px solid var(--line)}.boundary-telemetry>div{padding:14px 15px;border-right:1px solid var(--line)}.boundary-telemetry>div:last-child{border-right:0}.boundary-telemetry span,.boundary-checks span{display:block;color:var(--muted);font-size:.69rem;text-transform:uppercase;letter-spacing:.06em}.boundary-telemetry strong,.boundary-checks strong{display:block;margin-top:4px;font-size:.9rem}.boundary-detail-grid{display:grid;grid-template-columns:1.12fr .88fr;gap:14px}.boundary-check-panel,.boundary-reading-card{padding:21px;border:1px solid var(--line);border-radius:var(--radius-sm);background:var(--panel)}.boundary-check-panel>span,.boundary-reading-card>span{color:var(--accent);font-size:.72rem;font-weight:800;letter-spacing:.08em;text-transform:uppercase}.boundary-check-panel h3,.boundary-reading-card h3{margin:8px 0 13px}.boundary-checks{display:grid;grid-template-columns:1fr 1fr;border:1px solid var(--line);border-radius:10px;overflow:hidden}.boundary-checks>div{padding:13px 14px;border-right:1px solid var(--line)}.boundary-checks>div:last-child{border-right:0}.boundary-checks strong.pass{color:var(--accent-3)}.boundary-checks strong.fail{color:var(--danger)}.boundary-residual{margin-top:14px;height:8px;border-radius:999px;background:var(--panel-solid);overflow:hidden}.boundary-residual>i{display:block;height:100%;width:0;background:var(--accent-3);transition:width .12s linear}.boundary-check-panel p,.boundary-reading-card p{margin:13px 0 0;color:var(--muted);font-size:.9rem}.boundary-reading-card{background:linear-gradient(150deg,var(--panel-solid),var(--panel))}
.boundary-limit-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.boundary-takeaways{padding-top:72px}.boundary-next{margin-top:72px}.chapter-menu-link[href="#k06"].is-active span{color:var(--text)}
@media(max-width:1120px){.boundary-lab-shell{grid-template-columns:1fr}.boundary-controls{position:static;grid-template-columns:repeat(2,minmax(0,1fr))}.boundary-preset-row,.boundary-actions{align-self:end}.boundary-telemetry{grid-template-columns:repeat(3,1fr)}.boundary-telemetry>div:nth-child(3){border-right:0}.boundary-telemetry>div:nth-child(-n+3){border-bottom:1px solid var(--line)}.boundary-telemetry>div:nth-child(4){border-left:0}.boundary-detail-grid{grid-template-columns:1fr 1fr}}
@media(max-width:980px){.k06-header{grid-template-columns:1fr}.k06-index{max-width:700px}.boundary-family-grid,.boundary-limit-grid{grid-template-columns:1fr 1fr}.boundary-family-card.key{grid-column:1/-1}}
@media(max-width:760px){.boundary-chapter{padding-top:46px}.k06-header h1{font-size:clamp(2.7rem,15vw,4.6rem)}.boundary-condition-grid,.boundary-family-grid,.boundary-limit-grid,.boundary-detail-grid{grid-template-columns:1fr}.boundary-family-card.key{grid-column:auto}.boundary-controls{grid-template-columns:1fr}.boundary-telemetry{grid-template-columns:1fr 1fr}.boundary-telemetry>div{border-bottom:1px solid var(--line)}.boundary-telemetry>div:nth-child(odd){border-right:1px solid var(--line)}.boundary-telemetry>div:nth-child(even){border-right:0}.boundary-telemetry>div:last-child{grid-column:1/-1;border-right:0;border-bottom:0}.boundary-field-svg{min-height:270px}.boundary-panel-head{align-items:flex-start}.boundary-checks{grid-template-columns:1fr}.boundary-checks>div{border-right:0;border-bottom:1px solid var(--line)}.boundary-checks>div:last-child{border-bottom:0}.boundary-end-label,.boundary-axis-label,.boundary-mode-label{font-size:17px}}
@media(max-width:390px){.boundary-preset-row{grid-template-columns:1fr}.boundary-panel-head{padding:14px}.boundary-card,.boundary-family-card,.boundary-limit-grid article,.boundary-check-panel,.boundary-reading-card{padding:18px}.boundary-legend{padding-inline:14px;gap:10px}.boundary-end-label,.boundary-axis-label,.boundary-mode-label{font-size:19px}}
@media(max-width:680px){.boundary-next>div{min-width:0}.boundary-next h2,.boundary-next p{overflow-wrap:anywhere}.boundary-next .next-arrow{flex:0 0 auto}}