.intro-page{overflow:clip visible}.intro-page__header{margin-bottom:0}.intro-course{width:min(1120px,100% - 48px);margin:0 auto;padding:28px 0 120px}.intro-course__hero{text-align:center;max-width:680px;margin:80px auto 72px}.intro-course__kicker,.intro-section__eyebrow{color:var(--ref-orange);letter-spacing:.14em;text-transform:uppercase;font-size:.75rem;font-weight:900;font-family:var(--font-course)}.intro-course__hero h1{color:var(--color-foreground);font-family:var(--font-serif);margin:16px 0 20px;font-size:clamp(2.2rem,5.5vw,3.8rem);font-weight:700;line-height:1.15}.intro-course__hero p:last-child{max-width:600px;color:var(--color-foreground);opacity:.8;font-family:var(--font-serif);margin:0 auto;font-size:clamp(1.05rem,1.2vw,1.2rem);line-height:1.75}.intro-course__sections{flex-direction:column;gap:0;display:flex}.intro-section{border-top:1px solid var(--ref-gray-light);text-align:left;width:100%;max-width:680px;margin:0 auto;padding:80px 0}.intro-section__header{align-items:center;gap:16px;margin-bottom:24px;display:flex}.intro-section__num{color:var(--ref-gray);font-variant-numeric:tabular-nums;-webkit-user-select:none;user-select:none;flex-shrink:0;font-size:clamp(2.5rem,5vw,4rem);font-weight:900;line-height:1}.intro-section__eyebrow{font-family:var(--font-course);letter-spacing:.08em;text-transform:uppercase;margin:0;font-size:.8rem}.intro-section__title{color:var(--color-foreground);font-family:var(--font-serif);margin:0 0 28px;font-size:clamp(1.6rem,3.5vw,2.6rem);font-weight:700;line-height:1.2}.intro-section__para{color:var(--color-foreground);font-family:var(--font-serif);opacity:.9;margin:0 0 28px;font-size:clamp(1.05rem,1.15vw,1.15rem);line-height:1.8}.intro-section__note{border-left:3px solid var(--ref-blue);background:var(--surface-elevated);color:var(--color-foreground);font-family:var(--font-serif);text-align:center;border-radius:0 8px 8px 0;max-width:600px;margin:40px auto;padding:32px 48px;font-size:1.05rem;font-style:italic;line-height:1.75;position:relative}.intro-section__note:before{content:"“";font-size:3rem;line-height:1;font-family:var(--font-serif),Georgia,serif;color:var(--ref-gray);opacity:.35;-webkit-user-select:none;user-select:none;position:absolute;top:6px;left:16px}.intro-section__note:after{content:"”";font-size:3rem;line-height:1;font-family:var(--font-serif),Georgia,serif;color:var(--ref-gray);opacity:.35;-webkit-user-select:none;user-select:none;position:absolute;bottom:-12px;right:16px}.intro-section__visual{justify-content:center;width:min(560px,100%);margin:40px auto;display:flex}.latex-display,.intro-transform-visual,.intro-det-visual{box-shadow:none;background:0 0;border:none;place-items:center;gap:18px;padding:20px 0;display:grid}.latex-display--compact{min-height:auto;box-shadow:none;padding:18px}.latex-system{color:var(--ref-black);align-items:center;gap:16px;font-family:Georgia,Times New Roman,serif;font-size:clamp(1.5rem,4vw,2.45rem);line-height:1.35;display:flex}.latex-system__brace{color:var(--ref-orange);font-size:3.2em;font-weight:300;line-height:.8}.latex-system__rows{gap:8px;display:grid}.latex-matrix{color:var(--ref-black);grid-template-columns:auto auto auto;align-items:stretch;font-family:Georgia,Times New Roman,serif;font-size:clamp(1.4rem,3vw,2.25rem);line-height:1;display:inline-grid}.latex-matrix table{border-collapse:collapse;margin:0 8px}.latex-matrix td{text-align:center;vertical-align:middle;font-variant-numeric:tabular-nums;min-width:42px;height:44px;padding:0 8px}.latex-matrix__augmented{border-left:2px solid var(--ref-orange)}.latex-bracket{border-top:2px solid var(--ref-black);border-bottom:2px solid var(--ref-black);width:12px}.latex-bracket--left{border-left:2px solid var(--ref-black)}.latex-bracket--right{border-right:2px solid var(--ref-black)}.latex-caption{color:var(--ref-gray-dark);text-align:center;font-size:.86rem;line-height:1.55}.intro-transform-visual{grid-template-columns:minmax(160px,auto) minmax(220px,1fr)}.intro-mini-plane{width:min(320px,100%);color:var(--ref-gray)}.latex-equation{color:var(--ref-black);flex-wrap:wrap;justify-content:center;align-items:center;gap:16px;font-family:Georgia,Times New Roman,serif;font-size:clamp(1.3rem,3vw,2.1rem);display:flex}.intro-composition,.intro-inverse{flex-wrap:wrap;justify-content:center;align-items:center;display:flex}.intro-composition .latex-caption,.intro-inverse .latex-caption{flex-basis:100%}.intro-axb{align-content:center}.intro-transform-chip{border:2px solid var(--ref-blue);width:70px;height:70px;color:var(--ref-blue);place-items:center;font-size:1.35rem;font-weight:900;display:grid}.intro-transform-chip--orange{border-color:var(--ref-orange);color:var(--ref-orange)}.intro-transform-chip--purple{border-color:var(--ref-purple);color:var(--ref-purple)}.intro-transform-chip--identity{border-color:var(--ref-black);color:var(--ref-black)}.intro-flow-arrow{color:var(--ref-gray-dark);text-transform:uppercase;font-size:.85rem;font-weight:800}.intro-inverse-map{gap:12px;width:min(620px,100%);margin:0 auto;display:grid}.intro-inverse-lane{border:1px solid var(--ref-gray-light);background:var(--surface-elevated);border-radius:8px;grid-template-columns:minmax(52px,auto) auto minmax(52px,auto) auto minmax(52px,auto);justify-content:center;align-items:center;gap:10px;min-height:112px;padding:16px;display:grid}.intro-inverse-lane--works{background:#308dff0d}.intro-inverse-lane--fails{background:#ffa2300f}.intro-inverse-grid{border:2px solid var(--ref-blue);background:#308dff12;grid-template-rows:repeat(2,25px);grid-template-columns:repeat(2,25px);display:grid}.intro-inverse-grid span{border-bottom:1px solid #308dff42;border-right:1px solid #308dff42}.intro-inverse-grid--moved{border-color:var(--ref-orange);background:#ffa2301c;transform:skew(-18deg)translate(2px)}.intro-inverse-arrow{min-width:34px;color:var(--ref-orange);place-items:center;font-family:Georgia,Times New Roman,serif;font-size:1.12rem;font-weight:800;display:grid}.intro-inverse-arrow:after{content:"→";color:var(--ref-gray-dark);margin-left:5px;font-size:.95rem}.intro-inverse-arrow--undo{color:var(--ref-purple)}.intro-inverse-arrow--blocked{color:#c2410c}.intro-inverse-arrow--blocked:after{content:"×";color:#c2410c}.intro-inverse-dots{width:54px;height:54px;position:relative}.intro-inverse-dots span,.intro-inverse-line span{background:var(--ref-blue);border-radius:50%;width:10px;height:10px;position:absolute}.intro-inverse-dots span:first-child{top:9px;left:7px}.intro-inverse-dots span:nth-child(2){top:18px;left:32px}.intro-inverse-dots span:nth-child(3){top:36px;left:18px}.intro-inverse-line{border-bottom:3px solid var(--ref-orange);width:58px;height:28px;position:relative}.intro-inverse-line span{background:var(--ref-orange);bottom:-6px}.intro-inverse-line span:first-child{left:8px}.intro-inverse-line span:nth-child(2){left:24px}.intro-inverse-line span:nth-child(3){left:40px}.intro-inverse-dots--faded{opacity:.24}.intro-inverse-lane__label{color:var(--ref-gray-dark);font-family:var(--font-course);text-align:center;grid-column:1/-1;justify-items:center;gap:2px;font-size:.76rem;font-weight:900;line-height:1.25;display:grid}.intro-inverse-lane__label span{color:#686868b8;font-size:.68rem;font-weight:800}.intro-inverse-map__caption{margin-top:4px}.intro-area-svg{width:min(320px,100%)}.intro-course__closing{border-top:1px solid var(--ref-gray-light);text-align:center;max-width:680px;margin:80px auto 0;padding-top:60px}.intro-course__closing h2{color:var(--color-foreground);font-family:var(--font-serif);font-size:clamp(1.6rem,3.5vw,2.6rem);font-weight:700;line-height:1.2}.intro-course__closing p{max-width:600px;color:var(--color-foreground);opacity:.8;font-family:var(--font-serif);margin:16px auto 32px;font-size:clamp(1.05rem,1.2vw,1.2rem);line-height:1.75}.intro-course__cta{border:1px solid var(--color-foreground);color:var(--color-foreground);font-family:var(--font-course);border-radius:999px;align-items:center;gap:10px;padding:12px 24px;font-size:.9rem;font-weight:700;text-decoration:none;transition:background .2s,color .2s,transform .2s;display:inline-flex}.intro-course__cta:hover{background:var(--color-foreground);color:var(--background);transform:translateY(-1px)}.intro-section--hero{padding:96px 0}.intro-section--hero .intro-section__title{font-size:clamp(1.8rem,4vw,3rem)}.intro-section--hero .intro-section__visual{width:min(620px,100%);margin:48px auto}.intro-section--hero .intro-section__num{color:var(--ref-orange)}.intro-canvas-block{flex-direction:column;align-items:center;gap:16px;width:100%;display:flex}.intro-basis-guide{flex-wrap:wrap;justify-content:center;align-items:center;gap:12px;width:min(620px,100%);padding:4px 0;display:flex}.intro-basis-guide__item{justify-items:center;gap:8px;min-width:132px;display:grid}.intro-labeled-matrix{justify-items:center;gap:2px;width:max-content;display:grid}.intro-labeled-matrix__labels{width:calc(100% - 40px);margin:0 20px;display:grid}.intro-labeled-matrix__labels span{color:var(--ref-gray-dark);font-family:var(--font-course);text-align:center;font-size:.68rem;font-style:italic;font-weight:900;line-height:1}.intro-basis-guide__item .latex-matrix{font-size:clamp(1.15rem,2.4vw,1.55rem)}.intro-basis-guide__item .latex-matrix td{min-width:30px;height:32px;padding:0 5px}.intro-basis-guide__item--active .latex-bracket{border-color:var(--ref-orange)}.intro-basis-guide__label{color:var(--ref-black);font-family:var(--font-course);font-size:.78rem;font-weight:900}.intro-basis-guide__caption{color:var(--ref-gray-dark);font-family:var(--font-course);text-align:center;font-size:.76rem;font-weight:700;line-height:1.35}.intro-basis-guide__arrow{color:var(--ref-orange);font-family:Georgia,Times New Roman,serif;font-size:1.6rem;font-weight:700}.intro-basis-guide__equations{min-width:128px;color:var(--ref-blue);gap:6px;padding:4px 0;font-family:Georgia,Times New Roman,serif;font-size:clamp(1rem,2.1vw,1.25rem);font-weight:700;line-height:1.3;display:grid}.intro-canvas-frame{border:1px solid var(--ref-gray-light);aspect-ratio:560/340;background:#0f0f1a;border-radius:16px;width:100%;max-width:560px;position:relative;overflow:hidden;box-shadow:0 8px 24px #0000001f}.intro-canvas-frame>*,.intro-canvas-frame div,.intro-canvas-frame canvas{box-sizing:border-box!important;width:100%!important;max-width:100%!important;height:100%!important;max-height:100%!important;display:block!important;position:absolute!important;top:0!important;left:0!important}.intro-canvas-placeholder{color:#ffffffb8;width:100%;height:100%;font-family:var(--font-course);place-items:center;font-size:.82rem;font-weight:800;display:grid}.intro-canvas-controls{flex-wrap:wrap;justify-content:center;align-items:center;gap:10px;width:min(560px,100%);display:flex}.intro-replay-button,.intro-det-tab{border:1px solid var(--ref-gray);background:var(--ref-white);min-height:32px;color:var(--ref-gray-dark);cursor:pointer;font-family:var(--font-course);border-radius:999px;padding:6px 10px;font-size:.78rem;font-weight:900;transition:border-color .16s,background-color .16s,color .16s}.intro-replay-button:hover,.intro-det-tab:hover,.intro-det-tab--active{border-color:var(--ref-blue);color:var(--ref-blue);background:#308dff14}.intro-composition-map{grid-template-columns:repeat(2,minmax(170px,1fr));gap:12px;width:100%;max-width:620px;margin:0 auto;display:grid}.intro-composition-core{background:#308dff12;border:1px solid #308dff38;border-radius:8px;grid-column:1/-1;justify-content:center;align-items:center;min-height:116px;display:flex;position:relative;overflow:hidden}.intro-composition-plane{transform-origin:50%;opacity:.88;grid-template-columns:repeat(3,1fr);display:grid;position:absolute;inset:16px;transform:skew(-18deg)scaleX(1.08)}.intro-composition-plane span{border-bottom:1px solid #308dff38;border-right:1px solid #308dff38}.intro-composition-core__label{z-index:1;border:2px solid var(--ref-orange);background:var(--ref-white);width:58px;height:58px;color:var(--ref-orange);border-radius:50%;place-items:center;font-family:Georgia,Times New Roman,serif;font-size:1.7rem;font-weight:800;display:grid;box-shadow:0 10px 24px #308dff1f}.intro-composition-branch{border:1px solid var(--ref-gray-light);background:var(--surface-elevated);border-radius:8px;place-content:center;justify-items:center;gap:8px;min-height:96px;padding:14px;transition:border-color .2s,transform .2s;display:grid;position:relative}.intro-composition-branch:hover{border-color:var(--ref-orange);transform:translateY(-2px)}.intro-composition-branch:before{content:"";background:var(--ref-gray-light);width:1px;height:12px;position:absolute;top:-12px;left:50%}.intro-composition-branch__visual{justify-content:center;align-items:center;gap:9px;display:flex}.intro-composition-branch__label{color:var(--ref-gray-dark);font-family:var(--font-course);letter-spacing:.02em;text-align:center;justify-items:center;gap:2px;font-size:.72rem;font-weight:900;line-height:1.25;display:grid}.intro-composition-branch__label span{color:#686868b8;letter-spacing:0;font-size:.66rem;font-weight:800}.intro-composition-node,.intro-composition-point{border:2px solid var(--ref-blue);background:var(--ref-white);min-width:40px;height:40px;color:var(--ref-blue);border-radius:8px;place-items:center;padding:0 8px;font-family:Georgia,Times New Roman,serif;font-size:1.05rem;font-weight:800;display:grid}.intro-composition-node--result{border-color:var(--ref-orange);color:var(--ref-orange)}.intro-composition-node--undo{border-color:var(--ref-purple);color:var(--ref-purple)}.intro-composition-arrow,.intro-composition-loop{color:var(--ref-gray-dark);font-family:Georgia,Times New Roman,serif;font-size:1.15rem;font-weight:800}.intro-composition-loop{color:var(--ref-purple);font-size:1.7rem}.intro-area-box{border:2px solid var(--ref-blue);background:#308dff14;display:block}.intro-area-box--unit{width:32px;height:32px}.intro-area-box--scaled{border-color:var(--ref-orange);background:#ffa2301f;width:52px;height:28px;transform:skew(-14deg)}.intro-composition-formula{color:var(--ref-orange);font-family:Georgia,Times New Roman,serif;font-size:1.2rem;font-weight:800}.intro-composition-point{border-radius:50%;min-width:36px;height:36px}.intro-composition-point--unknown{color:var(--ref-gray-dark);border-style:dashed}.intro-composition-point--target{border-color:var(--ref-orange);color:var(--ref-orange)}.intro-composition-map__caption{grid-column:1/-1;margin-top:8px}@media (max-width:640px){.intro-section--hero{padding:64px 0}.intro-basis-guide{align-items:stretch;gap:10px;padding:0}.intro-basis-guide__item,.intro-basis-guide__equations{flex:100%}.intro-basis-guide__arrow{text-align:center;flex:100%;font-size:1.25rem;line-height:1}.intro-composition-map{grid-template-columns:1fr 1fr;gap:10px}.intro-composition-core{min-height:96px}.intro-composition-branch{gap:6px;min-height:84px;padding:10px}.intro-composition-node,.intro-composition-point{min-width:32px;height:32px;padding:0 6px;font-size:.9rem}}.intro-det-equations{flex-direction:row;justify-content:center;align-items:center;gap:32px;width:100%;display:flex}.intro-det-equation-group{flex-direction:column;align-items:center;gap:8px;display:flex}.intro-det-equation-label{font-family:var(--font-course);letter-spacing:.05em;font-size:.8rem;font-weight:700}.intro-det-equation-label--stretch{color:var(--ref-blue)}.intro-det-equation-label--collapse{color:var(--ref-orange)}.intro-det-equation-label--flip{color:var(--ref-purple)}.intro-det-divider{background-color:var(--ref-gray-light);align-self:center;width:1px;height:48px}@media (max-width:768px){.intro-det-equations{flex-direction:column;gap:20px}.intro-det-divider{display:none}}.intro-det-picker{flex-direction:column;align-items:center;gap:18px;width:100%;display:flex}.intro-det-tabs{flex-wrap:wrap;justify-content:center;gap:8px;display:flex}