:root{--ink:#111426;--muted:#697087;--paper:#f5f7ff;--white:#fff;--line:#e0e4ee;--blue:#3157f6;--blue-dark:#203fc5;--blue-soft:#e8edff;--violet:#704bd7;--green:#20a078;--yellow:#ffd45e;--nav:76px;--shadow:0 28px 70px rgba(28,43,108,.16)}
*,*::before,*::after{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:calc(var(--nav) + 20px)}body{margin:0;color:var(--ink);background:var(--paper);font-family:"Pretendard Variable",Pretendard,-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans KR",sans-serif;-webkit-font-smoothing:antialiased;word-break:keep-all}a{color:inherit;text-decoration:none}.container{width:min(1180px,calc(100% - 48px));margin-inline:auto}.section-pad{padding-block:120px}.skip-link{position:fixed;top:12px;left:12px;z-index:1000;padding:12px 18px;color:#fff;background:var(--ink);border-radius:10px;transform:translateY(-160%)}.skip-link:focus{transform:translateY(0)}
.site-header{position:sticky;top:0;z-index:100;height:var(--nav);background:rgba(245,247,255,.88);border-bottom:1px solid rgba(218,223,237,.85);backdrop-filter:blur(18px)}.navbar{height:100%;display:flex;align-items:center;justify-content:space-between;gap:30px}.brand{display:inline-flex;align-items:center;gap:10px;font-size:23px;font-weight:850;letter-spacing:-.9px}.brand-mark{width:34px;height:34px;display:grid;place-items:center;color:#fff;background:var(--blue);border-radius:10px;box-shadow:0 8px 16px rgba(49,87,246,.24);font-size:19px;font-weight:900;letter-spacing:-2px;transform:rotate(-4deg)}.nav-links{display:flex;gap:29px;margin-left:auto}.nav-links a,.login-link{position:relative;color:#4a5066;font-size:14px;font-weight:650}.nav-links a:hover,.nav-links .active,.login-link:hover{color:var(--blue)}.nav-links .active::after{content:"";position:absolute;right:0;bottom:-11px;left:0;height:2px;background:var(--blue);border-radius:99px}.nav-actions{display:flex;align-items:center;gap:18px}.button{display:inline-flex;align-items:center;justify-content:center;gap:10px;border:1px solid transparent;border-radius:12px;font-weight:750;line-height:1;transition:.2s ease}.button:hover{transform:translateY(-2px)}.button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid rgba(49,87,246,.28);outline-offset:3px}.button-small{min-height:42px;padding:0 18px;font-size:14px}.button-large{min-height:57px;padding:0 26px;font-size:15px}.button-primary{color:#fff;background:var(--blue);box-shadow:0 12px 26px rgba(49,87,246,.23)}.button-primary:hover{background:var(--blue-dark)}.button-secondary{background:#fff;border-color:var(--line)}.button-light{color:#fff;background:rgba(255,255,255,.1);border-color:rgba(255,255,255,.17)}.button-white{color:var(--blue);background:#fff;box-shadow:0 18px 36px rgba(15,23,73,.23)}
.mobile-menu{display:none;position:relative}.mobile-menu summary{width:40px;height:40px;display:grid;align-content:center;gap:5px;padding:9px;background:#fff;border:1px solid var(--line);border-radius:10px;cursor:pointer;list-style:none}.mobile-menu summary::-webkit-details-marker{display:none}.mobile-menu summary span{height:2px;background:var(--ink);border-radius:99px}.mobile-menu>div{position:absolute;top:50px;right:0;width:210px;display:grid;padding:10px;background:#fff;border:1px solid var(--line);border-radius:14px;box-shadow:0 14px 35px rgba(28,35,76,.1)}.mobile-menu>div a{padding:12px 13px;border-radius:9px;font-size:13px;font-weight:650}.mobile-menu>div a:hover{color:var(--blue);background:var(--blue-soft)}
.visual-hero{position:relative;overflow:hidden;padding:105px 0 125px;background:linear-gradient(145deg,#f9faff,#eef2ff)}.hero-grid-bg{position:absolute;inset:0;background-image:linear-gradient(rgba(53,68,131,.055) 1px,transparent 1px),linear-gradient(90deg,rgba(53,68,131,.055) 1px,transparent 1px);background-size:42px 42px;mask-image:radial-gradient(ellipse 72% 70% at 70% 45%,#000,transparent 80%)}.hero-layout{position:relative;z-index:2;display:grid;grid-template-columns:.88fr 1.12fr;align-items:center;gap:75px}.eyebrow{width:fit-content;display:flex;align-items:center;gap:9px;margin:0 0 24px;padding:8px 12px;color:#4d598b;background:#fff;border:1px solid var(--line);border-radius:999px;font-size:10px;font-weight:850;letter-spacing:1.2px}.eyebrow span{width:7px;height:7px;background:var(--blue);border-radius:50%;box-shadow:0 0 0 5px rgba(49,87,246,.11)}.hero-copy h1{margin:0;font-size:clamp(47px,5.1vw,70px);line-height:1.14;letter-spacing:-3.9px}.hero-copy h1 em{color:var(--blue);font-style:normal}.hero-copy>p:not(.eyebrow){margin:27px 0 0;color:var(--muted);font-size:16px;line-height:1.8}.hero-actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:32px}.hero-caption{display:flex;align-items:center;gap:8px;margin-top:30px;color:#8c93a9;font-size: 9px;font-weight:850;letter-spacing:.6px}.hero-caption i{width:18px;height:1px;background:#c8cdda}.hero-caption span:last-child{color:var(--green)}
.hero-demo{position:relative;padding:25px 0}.demo-window{overflow:hidden;background:#fff;border:1px solid #dce1ee;border-radius:28px;box-shadow:var(--shadow);transform:perspective(1300px) rotateY(-2deg)}.demo-bar{min-height:72px;display:flex;align-items:center;justify-content:space-between;padding:0 23px;border-bottom:1px solid #e7eaf2}.demo-topic{font-size:13px;font-weight:750}.demo-step{padding:7px 10px;color:var(--blue);background:var(--blue-soft);border-radius:999px;font-size:9px;font-weight:850}.demo-stage{min-height:330px;display:grid;grid-template-columns:150px 65px 210px;align-items:center;justify-content:center;gap:14px;padding:35px;background-image:radial-gradient(#d8ddea 1px,transparent 1px);background-size:20px 20px}.circle-model{position:relative;width:150px;height:150px;background:repeating-conic-gradient(var(--blue) 0 14deg,#9cacf9 14deg 28deg);border:4px solid #fff;border-radius:50%;box-shadow:0 0 0 2px var(--blue),0 14px 25px rgba(49,87,246,.18);animation:circle-spin 18s linear infinite}.circle-model::after{content:"";position:absolute;top:50%;left:50%;width:50%;height:2px;background:#fff}.circle-model i{position:absolute;top:44%;right:23%;z-index:2;color:#fff;font-family:"SUIT Variable", "Pretendard Variable", Pretendard, sans-serif;font-size:16px}.change-arrow{display:flex;flex-direction:column;align-items:center;gap:8px;color:#858da5}.change-arrow span{font-size: 9px;line-height:1.4;text-align:center}.change-arrow strong{color:var(--blue);font-size:27px;animation:arrow 1.8s ease-in-out infinite}.area-model{position:relative;width:210px;height:105px;background:linear-gradient(135deg,#a6b4fc,var(--blue));clip-path:polygon(9% 0,100% 0,91% 100%,0 100%);filter:drop-shadow(0 15px 14px rgba(49,87,246,.2))}.area-model::after{content:"";position:absolute;top:0;bottom:0;left:50%;width:1px;background:rgba(255,255,255,.35)}.area-model .top-length,.area-model .side-length{position:absolute;color:var(--blue);font-family:"SUIT Variable", "Pretendard Variable", Pretendard, sans-serif;font-size:14px;font-style:italic;font-weight:700}.top-length{top:-27px;left:45%}.side-length{top:43%;right:-18px}.demo-formula{min-height:76px;display:flex;align-items:center;justify-content:center;gap:17px;padding:15px;border-top:1px solid #e7eaf2;font-family:"SUIT Variable", "Pretendard Variable", Pretendard, sans-serif}.demo-formula span{color:#8b92a6;font-size:12px}.demo-formula i{color:#b1b6c4;font-style:normal}.demo-formula strong{color:#434a62;font-size:18px}.demo-formula em{padding:7px 11px;color:#fff;background:var(--blue);border-radius:8px;font-style:normal;font-weight:800}.demo-footer{min-height:47px;display:flex;align-items:center;justify-content:space-between;padding:0 23px;color:#7d8499;background:#fafbfe;font-size:9px}.demo-footer>div{display:flex;gap:5px}.demo-footer i{width:20px;height:4px;background:#dfe2eb;border-radius:99px}.demo-footer i.on{width:34px;background:var(--blue)}.float-label{position:absolute;z-index:5;display:flex;align-items:center;gap:10px;padding:11px 14px;background:rgba(255,255,255,.96);border:1px solid var(--line);border-radius:14px;box-shadow:0 14px 35px rgba(28,35,76,.1);animation:float 4s ease-in-out infinite}.float-label b{width:29px;height:29px;display:grid;place-items:center;color:var(--blue);background:var(--blue-soft);border-radius:9px;font-size:10px}.float-label span{color:#858b9e;font-size: 9px;line-height:1.4}.float-label strong{color:var(--ink);font-size:9px}.float-label-one{top:0;right:-24px}.float-label-two{bottom:0;left:-25px;animation-delay:-1.8s}
.section-heading{margin-bottom:52px}.row-heading{display:flex;align-items:flex-end;justify-content:space-between;gap:50px}.row-heading>p{margin:0;color:var(--muted);font-size:14px;line-height:1.75}.section-kicker{margin:0 0 14px;color:var(--blue);font-size:10px;font-weight:850;letter-spacing:1.7px}.section-heading h2,.step-copy h2,.difference-copy h2,.cta-inner h2{margin:0;font-size:clamp(36px,4.2vw,53px);line-height:1.25;letter-spacing:-2.7px}.visual-principles{background:#fff}.rule-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}.rule-grid article{position:relative;min-height:350px;padding:27px;background:#fff;border:1px solid var(--line);border-radius:21px;transition:.22s ease}.rule-grid article:hover{transform:translateY(-5px);box-shadow:0 17px 38px rgba(30,39,80,.08)}.rule-grid article>span{position:absolute;top:24px;right:24px;color:#a7adbd;font-family:"SUIT Variable", "Pretendard Variable", Pretendard, sans-serif;font-size:10px}.rule-icon{height:125px;display:grid;place-items:center;margin-bottom:25px;background:#f2f5ff;border-radius:15px}.icon-focus i{width:40px;height:40px;background:var(--blue);border:10px solid #cbd5ff;border-radius:50%;box-shadow:0 0 0 14px #e2e7ff}.icon-link{grid-template-columns:auto auto auto;gap:10px;padding:25px}.icon-link i{width:42px;height:42px;background:#aebcfb;border:2px solid var(--blue);border-radius:9px}.icon-link i:nth-child(2){background:#d9d0f6;border-color:var(--violet)}.icon-link b{position:absolute;color:var(--ink)}.icon-time i{width:54px;height:54px;border:6px solid #bdc9fd;border-top-color:var(--blue);border-radius:50%;animation:circle-spin 4s linear infinite}.icon-return{color:var(--green);font-size:40px;font-weight:500}.rule-grid h3{margin:0 0 12px;font-size:18px}.rule-grid p{margin:0;color:var(--muted);font-size:12px;line-height:1.7}
.example-section{background:#f1f3f9}.centered-heading{text-align:center}.example-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.example-card{overflow:hidden;padding:26px;background:#fff;border:1px solid var(--line);border-radius:23px;box-shadow:0 15px 35px rgba(28,38,78,.055)}.card-top{display:flex;align-items:center;justify-content:space-between}.card-top span{padding:7px 10px;color:var(--blue);background:var(--blue-soft);border-radius:8px;font-size:10px;font-weight:800}.card-top small{color:#9ba1b2;font-size: 9px;font-weight:800;letter-spacing:1px}.algebra-model,.mini-graph,.matrix-model{height:210px;margin:22px 0 25px;background:#f7f8fc;border:1px solid #eceef4;border-radius:16px}.algebra-model{display:grid;grid-template-columns:3fr 1fr;grid-template-rows:3fr 1fr;gap:3px;padding:28px 45px}.algebra-model>div{display:grid;place-items:center;font-family:"SUIT Variable", "Pretendard Variable", Pretendard, sans-serif}.x-square{color:#fff;background:var(--blue);font-size:22px}.x-rect{color:#35488e;background:#becafb}.nine{color:#534494;background:#c8b9f2}.mini-graph{position:relative;overflow:hidden;background-image:linear-gradient(rgba(80,94,151,.1) 1px,transparent 1px),linear-gradient(90deg,rgba(80,94,151,.1) 1px,transparent 1px);background-size:25px 25px}.mini-x,.mini-y{position:absolute;background:#7b8298}.mini-x{top:72%;left:0;width:100%;height:1px}.mini-y{top:0;left:24%;width:1px;height:100%}.curve-before,.curve-after{position:absolute;top:20%;width:100px;height:150px;border:3px solid;border-top:0;border-radius:0 0 48% 48%}.curve-before{left:18%;border-color:#c3c8d7}.curve-after{left:49%;border-color:var(--blue)}.mini-graph>span{position:absolute;top:45%;left:43%;color:var(--blue);font-weight:800}.matrix-model{display:flex;align-items:center;justify-content:center;gap:12px}.matrix{position:relative;display:grid;grid-template-columns:repeat(2,28px);grid-template-rows:repeat(2,28px);gap:3px;padding:6px;border-right:2px solid #7e8498;border-left:2px solid #7e8498}.matrix i{display:grid;place-items:center;background:#e9ecf5;font-size:10px;font-style:normal}.matrix.left i:nth-child(1),.matrix.left i:nth-child(2){color:#fff;background:var(--blue)}.matrix.right i:nth-child(1),.matrix.right i:nth-child(3){color:#fff;background:var(--violet)}.matrix.result i{color:#fff;background:var(--green)}.matrix-model>b{color:#969cad;font-size:14px}.example-card h3{margin:0 0 11px;font-size:20px}.example-card>p{min-height:62px;margin:0;color:var(--muted);font-size:12px;line-height:1.7}.card-formula{margin:22px -26px -26px;padding:18px 26px;color:#71788d;background:#fafbfe;border-top:1px solid #eceef4;font-family:"SUIT Variable", "Pretendard Variable", Pretendard, sans-serif;font-size:12px}.card-formula span{margin:0 7px;color:#b1b6c4}.card-formula strong{color:var(--blue)}
.step-section{color:#fff;background:var(--ink)}.step-layout{display:grid;grid-template-columns:.85fr 1.15fr;align-items:center;gap:95px}.section-kicker.light{color:#91a4ff}.step-copy>p:not(.section-kicker){margin:24px 0 33px;color:#a1a8bd;font-size:14px;line-height:1.8}.step-list{display:grid;gap:11px;margin:0;padding:0;list-style:none}.step-list li{display:grid;grid-template-columns:64px 1fr 45px;align-items:center;gap:16px;min-height:95px;padding:18px 21px;background:rgba(255,255,255,.055);border:1px solid rgba(255,255,255,.09);border-radius:17px}.step-list li.active{background:rgba(49,87,246,.19);border-color:rgba(111,135,255,.42)}.step-list li>span{color:#7e88aa;font-size: 9px;font-weight:850}.step-list li div{display:flex;flex-direction:column;gap:6px}.step-list strong{font-size:14px}.step-list p{margin:0;color:#9299b0;font-size:10px}.step-list b{width:42px;height:42px;display:grid;place-items:center;color:#aebaff;background:#242c4e;border-radius:12px;font-size:16px}.step-list .active b{color:#fff;background:var(--blue)}
.difference-section{background:#fff}.difference-grid{display:grid;grid-template-columns:.78fr 1.22fr;align-items:center;gap:90px}.difference-copy>p:not(.section-kicker){margin:23px 0 0;color:var(--muted);font-size:14px;line-height:1.8}.difference-cards{display:grid;grid-template-columns:repeat(2,1fr);gap:15px}.difference-cards article{padding:27px;border:1px solid var(--line);border-radius:21px}.difference-cards>article>span{font-size:10px;font-weight:850}.difference-cards ul{display:grid;gap:13px;margin:25px 0;padding:0;list-style:none}.difference-cards li{position:relative;padding-left:17px;color:var(--muted);font-size:11px}.difference-cards li::before{content:"";position:absolute;top:5px;left:0;width:6px;height:6px;border-radius:50%}.not-card{background:#f4f5f7}.not-card li::before{background:#a8adba}.yes-card{color:#fff;background:linear-gradient(145deg,var(--blue),#5940d0);box-shadow:0 20px 40px rgba(48,70,175,.2)}.yes-card li{color:#d7ddff}.yes-card li::before{background:var(--yellow)}.difference-cards strong{display:block;padding-top:18px;border-top:1px solid rgba(126,132,150,.2);font-size:12px}.yes-card strong{border-color:rgba(255,255,255,.16)}
.final-cta{padding:105px 0;color:#fff;background:linear-gradient(135deg,var(--blue),#5a3ed1)}.cta-inner{display:flex;flex-direction:column;align-items:center;text-align:center}.cta-inner>p{margin:0 0 16px;color:#c9d1ff;font-size:9px;font-weight:850;letter-spacing:2px}.cta-inner h2{font-size:clamp(39px,4.8vw,60px)}.cta-inner .button{margin-top:33px}.site-footer{color:#8a90a4;background:#0e1120}.footer-inner{min-height:85px;display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:30px}.footer-brand{color:#fff}.footer-inner p{margin:0;font-size:10px}.footer-inner>div{display:flex;justify-content:flex-end;gap:17px;font-size:9px}.footer-inner a:hover{color:#fff}
@keyframes circle-spin{to{transform:rotate(360deg)}}@keyframes arrow{0%,100%{transform:translateX(0)}50%{transform:translateX(7px)}}@keyframes float{0%,100%{transform:translateY(0)}50%{transform:translateY(-8px)}}
@media(max-width:1050px){.nav-links{gap:18px}.hero-layout{gap:38px}.demo-stage{grid-template-columns:125px 45px 170px}.circle-model{width:125px;height:125px}.area-model{width:170px;height:90px}.rule-grid{grid-template-columns:repeat(2,1fr)}.example-grid{grid-template-columns:1fr}.example-card{display:grid;grid-template-columns:1fr 1fr;column-gap:35px}.example-card .card-top,.example-card h3,.example-card>p,.example-card .card-formula{grid-column:2}.algebra-model,.mini-graph,.matrix-model{grid-column:1;grid-row:1/5}.card-formula{align-self:end}.step-layout,.difference-grid{gap:50px}}
@media(max-width:900px){:root{--nav:68px}.section-pad{padding-block:88px}.nav-links{display:none}.mobile-menu{display:block}.nav-actions{margin-left:auto}.visual-hero{padding:75px 0 95px}.hero-layout{grid-template-columns:1fr;gap:55px}.hero-copy{max-width:700px;margin:auto;text-align:center}.eyebrow,.hero-actions,.hero-caption{justify-content:center;margin-inline:auto}.hero-actions,.hero-caption{margin-top:28px}.hero-demo{width:min(680px,100%);margin:auto}.demo-window{transform:none}.row-heading{display:block}.row-heading>p{margin-top:20px}.step-layout,.difference-grid{grid-template-columns:1fr}.difference-copy,.step-copy{max-width:700px}.difference-cards{max-width:700px}.footer-inner{grid-template-columns:1fr auto}.footer-inner p{display:none}}
@media(max-width:640px){.container{width:min(100% - 32px,1180px)}.section-pad{padding-block:72px}.brand{font-size:20px}.brand-mark{width:31px;height:31px;font-size:17px}.login-link{display:none}.button-small{min-height:39px;padding:0 13px;font-size:12px}.visual-hero{padding-top:55px}.hero-copy h1{font-size:40px;letter-spacing:-2.5px}.hero-copy>p:not(.eyebrow){font-size:14px}.hero-actions{width:100%;display:grid}.hero-actions .button{width:100%}.hero-caption{display:none}.demo-bar{padding:0 15px}.demo-stage{min-height:440px;grid-template-columns:1fr;justify-items:center;gap:25px}.change-arrow{transform:rotate(90deg)}.change-arrow span{display:none}.demo-formula{flex-wrap:wrap;gap:10px}.demo-formula span{width:100%;text-align:center}.demo-footer span,.float-label{display:none}.section-heading h2,.step-copy h2,.difference-copy h2,.cta-inner h2{font-size:33px;letter-spacing:-1.8px}.rule-grid{grid-template-columns:1fr}.rule-grid article{min-height:320px}.example-card{display:block}.algebra-model,.mini-graph,.matrix-model{height:195px}.example-card>p{min-height:auto}.difference-cards{grid-template-columns:1fr}.step-list li{grid-template-columns:52px 1fr}.step-list li>b{display:none}.footer-inner>div a:first-child{display:none}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}

/* Interactive circle-area walkthrough */
.demo-window .circle-model,.demo-window .change-arrow,.demo-window .area-model,.demo-window .demo-formula>*{transition:opacity .42s ease,transform .55s cubic-bezier(.2,.75,.25,1),filter .42s ease}.demo-controls{display:flex;align-items:center;gap:6px}.demo-step-button{width:26px;height:24px;padding:0;color:#8b92a6;background:#e3e6ef;border:0;border-radius:8px;font-family:inherit;font-size:9px;font-weight:800;line-height:1;cursor:pointer;transition:width .22s ease,color .22s ease,background .22s ease,transform .22s ease}.demo-step-button:hover{color:var(--blue);transform:translateY(-1px)}.demo-step-button.active{width:60px;color:#fff;background:var(--blue);box-shadow:0 7px 15px rgba(49,87,246,.22)}.demo-step-button.active span::before{content:"STEP ";font-size: 9px}.demo-step-button:focus-visible{outline:3px solid rgba(49,87,246,.25);outline-offset:2px}.demo-window[data-current-step="1"] .circle-model{background:var(--blue);animation:visual-circle-breathe 2.4s ease-in-out infinite}.demo-window[data-current-step="1"] .change-arrow,.demo-window[data-current-step="1"] .area-model{opacity:0;transform:scale(.72)}.demo-window[data-current-step="1"] .demo-formula>*{opacity:.18;transform:translateY(6px)}.demo-window[data-current-step="2"] .circle-model{animation:visual-sector-focus 2.2s ease-in-out infinite}.demo-window[data-current-step="2"] .change-arrow,.demo-window[data-current-step="2"] .area-model{opacity:0;transform:scale(.78)}.demo-window[data-current-step="2"] .demo-formula>*{opacity:.28}.demo-window[data-current-step="3"] .circle-model{animation:circle-spin 8s linear infinite}.demo-window[data-current-step="3"] .change-arrow,.demo-window[data-current-step="3"] .area-model{opacity:1;transform:none}.demo-window[data-current-step="3"].is-changing .area-model{animation:visual-rearrange .7s cubic-bezier(.2,.8,.25,1) both}.demo-window[data-current-step="3"] .demo-formula span,.demo-window[data-current-step="3"] .demo-formula strong{opacity:1}.demo-window[data-current-step="3"] .demo-formula i,.demo-window[data-current-step="3"] .demo-formula em{opacity:.35}.demo-window[data-current-step="4"] .circle-model{opacity:.24;filter:saturate(.4);animation:none;transform:scale(.9)}.demo-window[data-current-step="4"] .change-arrow{opacity:.48}.demo-window[data-current-step="4"] .area-model{opacity:1;transform:scale(1.06);filter:drop-shadow(0 18px 16px rgba(49,87,246,.28))}.demo-window[data-current-step="4"] .demo-formula>*{opacity:1;transform:none}.demo-window[data-current-step="4"].is-changing .demo-formula em{animation:visual-formula-pop .65s cubic-bezier(.2,.8,.25,1) both}@keyframes visual-circle-breathe{0%,100%{box-shadow:0 0 0 2px var(--blue),0 14px 25px rgba(49,87,246,.18)}50%{box-shadow:0 0 0 9px rgba(49,87,246,.12),0 18px 32px rgba(49,87,246,.25)}}@keyframes visual-sector-focus{0%,100%{transform:rotate(0) scale(1)}50%{transform:rotate(14deg) scale(1.04)}}@keyframes visual-rearrange{0%{opacity:0;transform:translateX(-35px) skewX(-8deg) scale(.82)}100%{opacity:1;transform:translateX(0) skewX(0) scale(1)}}@keyframes visual-formula-pop{0%{transform:scale(.72)}65%{transform:scale(1.16)}100%{transform:scale(1)}}
@media(max-width:640px){.demo-window[data-current-step="1"] .change-arrow,.demo-window[data-current-step="2"] .change-arrow{transform:rotate(90deg) scale(.72)}.demo-window[data-current-step="3"] .change-arrow,.demo-window[data-current-step="4"] .change-arrow{transform:rotate(90deg)}.demo-footer .demo-step-button span{display:inline}.demo-step-button{height:27px}.demo-step-button.active{width:55px}}

/* Keep supporting badges outside the teaching canvas. */
.demo-badges{display:flex;align-items:center;justify-content:flex-end;gap:10px;padding:14px 8px 0}.demo-badges .float-label{position:static;animation:none;box-shadow:0 9px 24px rgba(28,35,76,.08)}

/* Step 4: explain where πr and r come from. */
.demo-stage{grid-template-columns:150px 65px 240px}.area-wrap{position:relative;width:240px;height:158px;display:flex;align-items:flex-start;padding-top:5px}.area-wrap .area-model{flex:0 0 auto}.dimension-label{position:absolute;z-index:3;display:flex;flex-direction:column;gap:2px;padding:7px 9px;color:#59617a;background:rgba(255,255,255,.97);border:1px solid #dce2f2;border-radius:8px;box-shadow:0 7px 16px rgba(34,48,104,.1);font-family:inherit;font-style:normal;line-height:1.2;opacity:0;transform:translateY(7px);transition:opacity .35s ease,transform .45s cubic-bezier(.2,.75,.25,1)}.dimension-label b{color:var(--blue);font-size:11px}.dimension-label small{font-size: 9px;white-space:nowrap}.base-label{bottom:0;left:33px;text-align:center}.height-label{top:36px;right:-2px}.demo-window[data-current-step="4"] .dimension-label{opacity:1;transform:none}.demo-window[data-current-step="4"].is-changing .base-label{transition-delay:.18s}.demo-window[data-current-step="4"].is-changing .height-label{transition-delay:.34s}.demo-formula strong b{font-style:normal}.demo-window[data-current-step="4"] .base-term{color:var(--blue)}.demo-window[data-current-step="4"] .height-term{color:var(--green)}
@media(max-width:1050px){.demo-stage{grid-template-columns:125px 45px 205px}.area-wrap{width:205px;height:145px}.base-label{left:18px}.height-label{top:30px;right:-2px}}
@media(max-width:640px){.demo-badges{display:none}.area-wrap{width:225px;height:155px}.base-label{left:26px}.height-label{top:34px;right:-2px}.demo-window[data-current-step="1"] .area-wrap,.demo-window[data-current-step="2"] .area-wrap{opacity:.25}}