.header { position: absolute; z-index: 10; inset: 0 0 auto; width: 100%; }
.shelf-home { position: relative; height: 100svh; min-height: 760px; overflow: hidden; background: #eee7dc; }
.room-scenery { position: absolute; inset: 0; pointer-events: none; }
.room-photograph { position: absolute; left: var(--photo-x); top: var(--photo-y); width: var(--photo-w); height: var(--photo-h); max-width: none; }
.room-photograph,.room-edge { mask-image: linear-gradient(to bottom, transparent, #000 42px); }
.room-edge { position: absolute; top: var(--photo-y); width: calc(var(--edge-w) + 1px); height: var(--photo-h); }
.room-left { left: 0; transform: scaleX(-1); }
.room-right { right: 0; transform: scaleX(-1); }
.room-upper { position: absolute; top: 0; left: 0; width: 100%; height: var(--upper-h); }
.room-lower { position: absolute; top: var(--lower-y); left: 0; width: 100%; height: var(--lower-h); }
.room-intro { position: absolute; top: 110px; left: 5%; right: 5%; text-align: center; }
.room-intro .eyebrow { justify-content: center; font-size: .75rem; color: #786956; letter-spacing: 1.8px; }
.room-intro h1 { font-size: clamp(3.4rem,5.4vw,5.4rem); line-height: 1; margin: 13px 0 17px; letter-spacing: -.05em; }
.room-intro h1 em { font-weight: 400; }
.room-intro>p:last-child { font-size: 1rem; line-height: 1.5; color: #625544; }
.room-intro>p:last-child br { display: none; }
.shelf-subjects { position: absolute; left: var(--opening-x); top: var(--opening-y); width: var(--opening-w); height: var(--opening-h); display: flex; align-items: flex-end; gap: 3px; padding: 0 var(--shelf-pad); }
.shelf-binder { position: relative; flex: 0 0 var(--binder-w); height: var(--binder-h); transform-origin: 50% 95%; transition: transform .4s var(--ease),filter .4s; filter: drop-shadow(5px 3px 3px #382b2338); }
.shelf-binder img { display: block; width: 100%; height: 100%; }
.shelf-binder span { position: absolute; left: 50%; top: 31%; white-space: nowrap; transform: translate(-50%,-50%) rotate(90deg); font-size: clamp(.65rem,calc(var(--binder-h)*.073),1.05rem); font-weight: 500; color: #343830; }
.binder-math img { filter: hue-rotate(96deg) saturate(1.18); }
.binder-german img { filter: saturate(.9); }
.binder-english img { filter: hue-rotate(-58deg) saturate(1.32); }
.shelf-binder:hover, .shelf-binder:focus-visible { transform: translateY(-10px) rotate(-3deg); filter: drop-shadow(12px 8px 6px #382b233f); }
.binder-english:hover, .binder-english:focus-visible { transform: translateY(-10px) rotate(3deg); }
.shelf-binder:active { transform: translateY(-16px) scale(1.03); }
.shelf-invitation { font-family: "Bradley Hand", "Segoe Print", cursive; align-self: center; color: #6e5e48; margin: 15% 0 0 9%; font-size: 1.2rem; line-height: 1.45; transform: rotate(-5deg); }
.shelf-invitation>span { color: #4b3a2e; }
.room-bottom { position: absolute; left: 5%; right: 5%; bottom: 21px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.room-bottom>span { font-size: .75rem; letter-spacing: .7px; color: #706653; }
.room-bottom>a { display: flex; align-items: center; justify-content: center; gap: 19px; background: #fffdf4e8; border: 1px solid #e3dac7; border-radius: 99px; padding: 15px 23px; font-size: .875rem; color: #4b3a2e; box-shadow: 0 6px 17px #5f4b3212; }
.room-bottom>a:hover { background: #fffdf9; }
.notebook-basics { padding-top: 100px; padding-bottom: 80px; }
.basics-heading { margin-bottom: 54px; }
.basics-heading .eyebrow { color: var(--otter-mid); margin-bottom: 25px; }
.basics-heading h2 { font: 400 clamp(2.8rem,4.5vw,4.3rem)/1.08 Georgia,serif; color: var(--otter-dark); letter-spacing: -.045em; }
.basics-heading>p:last-child { margin-top: 23px; font-size: 1.1rem; line-height: 1.65; color: var(--muted); }
.basics-layout { display: grid; grid-template-columns: .82fr 1.18fr; gap: 8%; align-items: center; }
.feature-choices { border-top: 1px solid var(--line); }
.feature-choices button { width: 100%; display: flex; gap: 17px; align-items: flex-start; text-align: left; background: transparent; padding: 28px 0; border-bottom: 1px solid var(--line); }
.feature-choices button>span:nth-child(2) { display: flex; flex-direction: column; gap: 11px; }
.feature-choices strong { font-size: 1.2rem; line-height: 1.3; font-weight: 550; letter-spacing: -.02em; color: var(--otter-dark); }
.feature-choices button>span:nth-child(2)>span { font-size: 1rem; color: var(--muted); line-height: 1.7; }
.feature-number { font-size: .75rem; color: #8b7b66; padding-top: 5px; }
.feature-indicator { margin-left: auto; font-size: 1.2rem; color: #9f9485; transition: transform .25s; }
.feature-choices [aria-selected=true] .feature-indicator { color: #4b3a2e; transform: rotate(45deg); }
.feature-choices [aria-selected=true] .feature-number { color: #4b3a2e; font-weight: 700; }
.feature-choices [aria-selected=true] strong { text-decoration: underline; text-decoration-color: #b89572; text-decoration-thickness: 1px; text-underline-offset: 6px; }
.feature-stage { min-width: 0; }
.feature-panel { background: #fffdf9; border: 1px solid #ded6c8; border-radius: 13px; overflow: hidden; box-shadow: 0 18px 45px -22px #4b3a2e36, 2px 3px 0 #eae3d6; animation: feature-in .35s var(--ease); }
.feature-panel[hidden] { display: none; }
.app-screen-header { display: flex; align-items: center; justify-content: space-between; gap: 15px; padding: 17px 21px; border-bottom: 1px solid #e7e2d8; font-size: .875rem; color: #695c4a; }
.app-screen-header>span>span { margin: 0 8px; color: #a09785; }
.app-screen-header>span:last-child { font-size: .75rem; letter-spacing: .5px; }
.writing-screen,.organization-screen { height: 490px; overflow: hidden; }
.writing-screen img { display: block; width: 100%; height: auto; transform: translateY(-6.5%); }
.organization-screen img { display: block; width: 100%; height: auto; transform: translateY(-16%); }
.feature-caption { border-top: 1px solid #e9e2d6; padding: 15px 21px; font-size: .875rem; color: var(--muted); background: #fffdf9; }
.pdf-preview { min-height: 490px; position: relative; padding: 26px; background: #ede9e1; }
.pdf-slide { background: white; padding: 26px 30px 23px; position: relative; box-shadow: 1px 3px 8px #594a3017; }
.pdf-slide>p:first-child { font-size: .75rem; letter-spacing: 1px; color: #8b8276; }
.pdf-slide h3 { font-size: 2.25rem; font-family: Georgia,serif; font-weight: 400; margin: 16px 0 9px; }
.pdf-slide>p { font-size: .875rem; line-height: 1.5; }
.pdf-diagram { position: relative; }
.pdf-graph { width: 100%; height: 190px; margin-top: 8px; fill: #577499; }
.pdf-graph path { fill: none; }
.graph-axes { stroke: #b6b7b6; stroke-width: 1; }
.graph-curve { stroke: #557c9e; stroke-width: 3; }
.graph-tangent { stroke: #b8835d; stroke-width: 2; }
.pdf-graph text { font: italic 16px Georgia,serif; }
.pdf-annotation { position: absolute; top: 12px; left: 0; color: #3e639d; font-size: 1.125rem; max-width: 130px; transform: rotate(-6deg); }
.pdf-underlined { border-bottom: 2px solid #b6ca86; width: fit-content; }
.pdf-underlined span { margin: 0 15px; }
.pdf-margin-note { margin: 16px 10px 0; font-size: 1rem; color: #49688f; transform: rotate(-2deg); }
.basics-bottom { border-top: 1px solid var(--line); display: grid; grid-template-columns: 1fr 1fr; gap: 8%; margin-top: 57px; padding-top: 28px; }
.basics-bottom>div { display: flex; gap: 17px; }
.basics-bottom>div>span { color: var(--otter-mid); font-size: 1.5rem; }
.basics-bottom p { font-size: .9375rem; line-height: 1.7; color: var(--muted); }
.basics-bottom strong { display: block; font-weight: 550; color: var(--otter-dark); }
.demo-section { border-top: 1px solid var(--line); padding-block: 85px; }
.demo-title { font: 400 clamp(3rem,5vw,4.8rem)/1.08 Georgia,serif; letter-spacing: -.045em; color: var(--otter-dark); margin: 27px 0; }
.demo-section .hero-note { font-size: 1rem; line-height: 1.7; max-width: 345px; margin-top: 28px; }
.demo-section .hero-description { font-size: 1.15rem; }
.faq { border-top: 1px solid var(--line); }
@keyframes feature-in { from {opacity: 0; transform: translateY(5px);} to {opacity: 1; transform: translateY(0);} }
@media(min-width:1600px) { .shelf-home { max-height: 1200px; } }
@media(max-width:1000px) {
  .room-bottom>span { display: none; }
  .room-bottom { justify-content: center; }
  .basics-layout { gap: 5%; }
  .feature-choices strong { font-size: 1.1rem; }
  .feature-choices button { gap: 11px; }
  .feature-choices button>span:nth-child(2)>span { font-size: .9375rem; }
  .app-screen-header { padding: 15px; }
  .app-screen-header>span:last-child { display: none; }
  .writing-screen,.organization-screen { height: 430px; }
  .pdf-preview { min-height: 430px; }
  .pdf-preview { padding: 18px; }
  .pdf-slide { padding: 22px; }
  .pdf-graph { height: 160px; }
  .pdf-annotation { top: 8px; font-size: 1rem; }
}
@media(max-width:760px) {
  .header { padding-block: 21px; }
  .header .nav-story { display: none; }
  .shelf-home { min-height: 780px; }
  .room-intro { top: 123px; }
  .room-intro h1 { font-size: 3.65rem; max-width: 290px; margin: 18px auto; }
  .room-intro>p:last-child { font-size: 1rem; }
  .room-intro>p:last-child br { display: initial; }
  .room-intro .eyebrow { font-size: .75rem; letter-spacing: 1px; }
  .shelf-binder { min-width: 42px; }
  .shelf-invitation { margin: 6% 0 0 5%; font-size: 1rem; }
  .shelf-invitation>span:last-child { display: none; }
  .room-bottom { bottom: 25px; }
  .room-bottom>a { font-size: .875rem; padding: 14px 20px; }
  .notebook-basics { padding-top: 65px; padding-bottom: 65px; }
  .basics-heading { margin-bottom: 30px; }
  .basics-heading h2 { font-size: 2.65rem; }
  .basics-heading>p:last-child { font-size: 1rem; }
  .basics-heading>p:last-child br { display: none; }
  .basics-layout { grid-template-columns: 1fr; gap: 29px; }
  .feature-choices button { padding: 21px 0; gap: 13px; }
  .feature-choices strong { font-size: 1.15rem; }
  .feature-choices button>span:nth-child(2)>span { font-size: 1rem; }
  .feature-choices [aria-selected=false]>span:nth-child(2)>span { display: none; }
  .writing-screen,.organization-screen { height: 390px; }
  .pdf-preview { height: auto; min-height: 440px; }
  .feature-caption { font-size: .875rem; padding: 13px 17px; }
  .basics-bottom { grid-template-columns: 1fr; gap: 25px; margin-top: 35px; padding-top: 27px; }
  .demo-section { padding-top: 65px; padding-bottom: 60px; }
  .demo-title { font-size: 3.15rem; }
  .demo-section .hero-note { font-size: 1rem; max-width: 400px; }
}
@media(max-width:390px) {
  .room-intro h1 { font-size: 3.25rem; max-width: 250px; }
  .shelf-invitation { font-size: .9rem; margin-left: 6%; }
  .shelf-binder { min-width: 39px; }
  .basics-heading h2 { font-size: 2.4rem; }
  .pdf-annotation { left: 0; font-size: .9rem; max-width: 115px; }
}
@media(prefers-reduced-motion:reduce) { .shelf-binder:hover,.shelf-binder:focus-visible,.shelf-binder:active { transform: none; } }