:root{
  --ink:#16213a;--navy:#1d3a66;--navy-dark:#142a4b;--accent:#159fb3;--accent-soft:#e3f5f8;
  --muted:#5d6878;--line:#e3e8ef;--tint:#f5f7fa;--paper:#fff;
  --body:24px;--small:19px;--radius:14px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:90px}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;background:var(--paper);color:var(--ink);font-family:"Zen Kaku Gothic New","Hiragino Sans","Yu Gothic",sans-serif;font-size:var(--body);line-height:1.85;-webkit-text-size-adjust:100%;-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto;display:block}
a{color:var(--navy)}
:focus-visible{outline:3px solid var(--accent);outline-offset:3px}
h1,h2,h3{line-height:1.4;font-weight:700;margin:0;letter-spacing:.01em}
p{margin:0 0 1em}
.nb{display:inline-block}
.note{font-size:var(--small);color:var(--muted)}
.center{text-align:center}

/* header */
.topbar{display:none}
.header{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:32px;padding:16px max(24px,calc((100vw - 1200px)/2));background:rgba(255,255,255,.92);backdrop-filter:saturate(1.4) blur(10px);transition:box-shadow .3s,padding .3s}
.header.scrolled{box-shadow:0 1px 0 var(--line),0 6px 24px rgba(20,33,58,.06);padding-top:10px;padding-bottom:10px}
.brand{display:flex;align-items:center;gap:10px;color:var(--ink);text-decoration:none;margin-right:auto}
.brand svg{width:38px;flex:none;fill:none;stroke:var(--accent);stroke-width:3;stroke-linecap:round;stroke-linejoin:round}
.brand-text{display:flex;flex-direction:column;line-height:1.3}
.brand-text b{font-size:24px;letter-spacing:.06em}
.brand-text small{font-size:13px;color:var(--muted)}
.gnav{display:flex;gap:26px;font-size:17px;font-weight:500}
.gnav a{color:var(--ink);text-decoration:none;position:relative;padding:4px 0}
.gnav a::after{content:"";position:absolute;left:0;right:0;bottom:-2px;height:2px;background:var(--accent);transform:scaleX(0);transform-origin:left;transition:transform .25s}
.gnav a:hover::after{transform:scaleX(1)}

/* buttons */
.btn{display:inline-block;text-align:center;text-decoration:none;font-weight:700;border-radius:999px;padding:12px 26px;font-size:18px;line-height:1.4;transition:background .2s,transform .2s,box-shadow .2s}
.btn-primary{background:var(--navy);color:#fff;box-shadow:0 6px 18px rgba(29,58,102,.22)}
.btn-primary:hover{background:var(--navy-dark);transform:translateY(-2px);box-shadow:0 10px 24px rgba(29,58,102,.28)}
.btn-lg{font-size:21px;padding:16px 36px}
.header-cta{font-size:16px;padding:10px 20px}
.text-link{font-weight:700;text-decoration:none;border-bottom:2px solid var(--accent);padding-bottom:2px}

/* layout */
.section{padding:110px 24px}
.section>*{max-width:1100px;margin-left:auto;margin-right:auto}
.section h2{font-size:clamp(32px,3.4vw,44px);text-align:center;margin-bottom:56px}
.tint{background:var(--tint)}

/* reveal */
.reveal.pending{opacity:0;transform:translateY(24px);transition:opacity .7s ease,transform .7s ease}
.reveal.pending.shown{opacity:1;transform:none}
.courses .reveal:nth-child(2),.features .reveal:nth-child(2),.plans .reveal:nth-child(2){transition-delay:.12s}
.features .reveal:nth-child(3),.plans .reveal:nth-child(3){transition-delay:.24s}

/* hero */
.hero{display:grid;grid-template-columns:minmax(0,.95fr) minmax(0,1.05fr);gap:56px;align-items:center;max-width:1200px;margin:0 auto;padding:72px 24px 88px}
.hero-tag{font-size:20px;color:var(--accent);font-weight:700;margin-bottom:14px}
.hero h1{font-size:clamp(34px,3.6vw,52px);margin-bottom:24px}
.hero-lead{color:#3a4558}
.hero-cta{display:flex;flex-wrap:wrap;gap:22px 28px;align-items:center;margin-top:34px}
.hero-text>*{animation:rise .8s ease both}
.hero-text>:nth-child(2){animation-delay:.08s}.hero-text>:nth-child(3){animation-delay:.16s}.hero-text>:nth-child(4){animation-delay:.24s}
.lab{animation:rise .9s .2s ease both}
@keyframes rise{from{opacity:0;transform:translateY(18px)}to{opacity:1;transform:none}}
@media (prefers-reduced-motion:reduce){.hero-text>*,.lab{animation:none}}

/* circuit lab */
.lab{margin:0;background:linear-gradient(180deg,#f7fafc,#eef3f8);border-radius:24px;padding:28px 28px 22px;box-shadow:inset 0 0 0 1px var(--line)}
.circuit{width:100%;height:auto;overflow:visible}
.circuit .wire{fill:none;stroke:#c9d3df;stroke-width:6;stroke-linejoin:round}
.circuit .current{fill:none;stroke:var(--accent);stroke-width:6;stroke-linecap:round;stroke-dasharray:2 26}
.circuit .part rect{fill:#f3f7fa;stroke:none}
.circuit .symbol{fill:none;stroke:var(--ink);stroke-width:4;stroke-linecap:round;stroke-linejoin:round}
.circuit .led .symbol{fill:#fff}
.circuit .glow{fill:#ffd84a;opacity:.5;filter:blur(10px);transition:opacity .3s}
.circuit text{font-size:20px;fill:var(--muted);font-family:inherit;text-anchor:middle}
.circuit .part:nth-of-type(2) text{text-anchor:end}
.circuit .led text{text-anchor:start}
.lab-controls{display:grid;grid-template-columns:1fr 1fr;gap:10px 24px;margin-top:10px}
.lab-controls .ctl{font-size:18px;font-weight:700;display:flex;flex-wrap:wrap;align-items:baseline;gap:0 6px}
.lab-controls output{font-size:26px;color:var(--navy);min-width:1.4em;text-align:right}
.lab-controls input{width:100%;accent-color:var(--accent);height:28px;cursor:pointer}
.formula{grid-column:1/-1;margin:6px 0 0;font-size:22px;font-weight:700;text-align:center;background:#fff;border-radius:10px;padding:10px}
.formula span{color:var(--accent);font-size:28px}
.lab figcaption{font-size:16px;color:var(--muted);margin-top:12px;text-align:center}

/* facts */
.facts{display:grid;grid-template-columns:repeat(3,1fr);max-width:1100px;margin:0 auto;padding:0 24px}
.facts>div{padding:26px 28px;border-top:1px solid var(--line);border-bottom:1px solid var(--line);line-height:1.45}
.facts>div+div{border-left:1px solid var(--line)}
.facts span{display:block;font-size:17px;color:var(--muted)}
.facts b{font-size:38px;color:var(--navy);letter-spacing:.02em}
.facts small{display:block;font-size:15px;color:var(--muted);margin-top:4px}

/* worries */
.worries{list-style:none;padding:0;display:grid;grid-template-columns:1fr 1fr;gap:18px 48px}
.worries li{position:relative;padding:4px 0 4px 34px}
.worries li::before{content:"";position:absolute;left:0;top:.62em;width:14px;height:14px;border-radius:50%;border:3px solid var(--accent)}
.worries-after{text-align:center;margin-top:44px;font-weight:700;font-size:26px}

/* courses */
.courses{display:grid;grid-template-columns:1fr 1fr;gap:32px}
.course{background:#fff;border-radius:var(--radius);overflow:hidden;box-shadow:0 1px 2px rgba(20,33,58,.05),0 12px 32px rgba(20,33,58,.06);transition:transform .35s,box-shadow .35s}
.course:hover{transform:translateY(-4px);box-shadow:0 2px 4px rgba(20,33,58,.05),0 20px 44px rgba(20,33,58,.1)}
.course-img{overflow:hidden;aspect-ratio:16/10}
.course-img img{width:100%;height:100%;object-fit:cover;transition:transform .8s ease}
.course:hover .course-img img{transform:scale(1.04)}
.course-body{padding:28px 32px 32px}
.course-for{font-size:17px;color:var(--accent);font-weight:700;margin:0 0 2px}
.course h3{font-size:30px;margin-bottom:14px}
.units{padding-left:1.1em;margin:0 0 20px;font-size:22px}
.units li{margin-bottom:4px}
.units li::marker{color:var(--accent)}
.more{font-weight:700;font-size:19px;text-decoration:none;border-bottom:2px solid var(--accent)}
#subjects .note{margin-top:24px;text-align:center}

/* binary toy */
.binary{display:grid;grid-template-columns:1fr 1.1fr;gap:56px;align-items:center}
.binary h2{text-align:left;margin-bottom:20px}
.bits{display:grid;grid-template-columns:repeat(8,1fr);gap:8px}
.bits button{font:inherit;border:0;border-radius:12px;background:var(--tint);box-shadow:inset 0 0 0 1px var(--line);padding:14px 0 8px;cursor:pointer;display:flex;flex-direction:column;align-items:center;transition:background .2s,transform .15s,box-shadow .2s;color:var(--ink)}
.bits button b{font-size:34px;line-height:1.1}
.bits button small{font-size:14px;color:var(--muted)}
.bits button:hover{transform:translateY(-2px)}
.bits button[aria-pressed=true]{background:var(--navy);color:#fff;box-shadow:0 6px 16px rgba(29,58,102,.25)}
.bits button[aria-pressed=true] small{color:#cfe0f5}
.binary-out{display:flex;justify-content:center;gap:40px;margin:22px 0 0;font-size:20px;color:var(--muted)}
.binary-out b{font-size:40px;color:var(--navy);margin-left:8px;font-variant-numeric:tabular-nums}

/* features */
.features{display:grid;grid-template-columns:repeat(3,1fr);gap:28px}
.feature{background:#fff;border-radius:var(--radius);padding:34px 30px;border-top:4px solid var(--accent)}
.feature h3{font-size:26px;margin-bottom:14px}
.feature p{margin:0;font-size:21px;color:#3a4558}

/* plans */
.plans{display:grid;grid-template-columns:1.2fr 1fr 1fr;gap:24px;align-items:stretch}
.plan{border-radius:var(--radius);padding:32px 30px;box-shadow:inset 0 0 0 1px var(--line);background:#fff}
.plan h3{font-size:26px}
.plan-spec{color:var(--muted);font-size:19px;margin:4px 0 10px}
.plan-price{margin:0 0 14px;font-size:20px}
.plan-price b{font-size:52px;color:var(--navy);line-height:1.1;letter-spacing:.01em}
.plan-price s{display:block;font-size:18px;color:var(--muted)}
.plan-price small{font-size:16px;color:var(--muted)}
.plan>p:last-child{margin:0;font-size:20px;color:#3a4558}
.plan-main{background:var(--navy);color:#fff;box-shadow:0 18px 40px rgba(29,58,102,.25)}
.plan-main .plan-spec,.plan-main .plan-price s,.plan-main .plan-price small,.plan-main>p:last-child{color:#c9d7ea}
.plan-main .plan-price b{color:#fff}
.plan-badge{display:inline-block;font-size:15px;font-weight:700;background:var(--accent);color:#fff;border-radius:999px;padding:2px 14px;margin-bottom:12px}
#price .note{margin-top:28px}

/* teacher */
.teacher{max-width:860px}
.teacher h2{margin-bottom:36px}
.teacher .note{margin:0}

/* flow */
.flow{list-style:none;padding:0;display:grid;grid-template-columns:repeat(4,1fr);gap:28px;counter-reset:step;position:relative}
.flow::before{content:"";position:absolute;top:22px;left:22px;right:22px;height:2px;background:var(--line)}
.flow::after{content:"";position:absolute;top:22px;left:22px;right:22px;height:2px;background:var(--accent);transform:scaleX(0);transform-origin:left;transition:transform 1.4s ease .2s}
.flow.shown::after,.flow:not(.pending)::after{transform:scaleX(1)}
.flow li{counter-increment:step;position:relative}
.flow li::before{content:counter(step);display:grid;place-items:center;width:46px;height:46px;border-radius:50%;background:#fff;box-shadow:inset 0 0 0 2px var(--accent);color:var(--navy);font-weight:700;font-size:21px;margin-bottom:16px;position:relative;z-index:1}
.flow h3{font-size:24px;margin-bottom:8px}
.flow p{font-size:20px;margin:0;color:#3a4558}

/* faq */
.faq-list{max-width:900px}
.faq-list details{background:#fff;border-radius:12px;margin-bottom:12px;box-shadow:inset 0 0 0 1px var(--line)}
.faq-list summary{cursor:pointer;list-style:none;font-weight:700;padding:22px 64px 22px 28px;position:relative}
.faq-list summary::-webkit-details-marker{display:none}
.faq-list summary::after{content:"";position:absolute;right:28px;top:50%;width:12px;height:12px;border:solid var(--navy);border-width:0 3px 3px 0;transform:translateY(-70%) rotate(45deg);transition:transform .25s}
.faq-list details[open] summary::after{transform:translateY(-30%) rotate(-135deg)}
.faq-list details p,.faq-a p{padding:0 28px 24px;margin:0;color:#3a4558}
.faq-list details[open] .faq-a{animation:open .3s ease}
@keyframes open{from{opacity:0;transform:translateY(-6px)}to{opacity:1;transform:none}}

/* booking (built by script.js) + form */
.booking{background:#fff}
.booking>p{text-align:center}
.calendar-toolbar{display:flex;flex-wrap:wrap;align-items:center;gap:10px;margin-bottom:12px}
.calendar-toolbar button{font:inherit;font-size:17px;padding:6px 16px;border:0;background:var(--tint);box-shadow:inset 0 0 0 1px var(--line);color:var(--navy);border-radius:999px;cursor:pointer}
.calendar-toolbar button:hover{background:var(--accent-soft)}
.calendar-toolbar strong{font-size:22px;margin:0 8px}
.calendar-toolbar span{font-size:var(--small);color:var(--muted);margin-left:auto}
#availability-status{font-size:var(--small);color:var(--muted)}
.calendar-scroll{overflow-x:auto;border-radius:var(--radius);box-shadow:inset 0 0 0 1px var(--line)}
#schedule{border-collapse:collapse;width:100%;min-width:760px;font-size:19px}
#schedule th,#schedule td{border-bottom:1px solid var(--line);padding:6px;text-align:center}
#schedule thead th{background:var(--tint);font-weight:700}
#schedule tbody th{color:var(--muted);font-weight:500}
#schedule td{color:#b6bfca}
#schedule button{font:inherit;width:100%;min-height:44px;border:0;border-radius:8px;background:var(--accent-soft);color:var(--navy);font-size:22px;font-weight:700;cursor:pointer;transition:background .2s}
#schedule button:hover:not(:disabled){background:#c9edf2}
#schedule button:disabled{background:transparent;color:#b6bfca;font-size:15px;cursor:default}
#schedule button.chosen{background:var(--navy);color:#fff}
.trial{padding-top:40px;background:#fff}
.trial h2{margin-bottom:20px}
.trial-lead{text-align:center}
.form{max-width:760px;background:var(--tint);border-radius:20px;padding:36px 40px}
.form label{display:block;font-weight:700;font-size:20px;margin-bottom:20px}
.form input:not([type=checkbox]),.form select{display:block;width:100%;margin-top:6px;font:inherit;font-size:22px;padding:10px 14px;border:0;box-shadow:inset 0 0 0 1px var(--line);border-radius:10px;background:#fff;color:var(--ink);min-height:56px}
.form input:not([type=checkbox]):focus,.form select:focus{box-shadow:inset 0 0 0 2px var(--accent);outline:0}
.form input[readonly]{background:#f9fbfc}
.form .consent{display:flex;gap:10px;align-items:center;font-weight:400}
.form .consent input{width:24px;height:24px;accent-color:var(--navy)}
.privacy-copy{font-size:var(--small);color:var(--muted)}
.submit{width:100%;font:inherit;font-weight:700;font-size:23px;padding:16px;border:0;border-radius:999px;background:var(--navy);color:#fff;cursor:pointer;transition:background .2s}
.submit:hover:not(:disabled){background:var(--navy-dark)}
.submit:disabled{background:#c3cad3;cursor:not-allowed}
#result{font-weight:700;margin-top:14px}

/* subpages */
.breadcrumb{max-width:1100px;margin:0 auto;padding:18px 24px 0;font-size:16px;color:var(--muted)}
.breadcrumb a{color:var(--muted)}
.page-hero{display:block;padding:48px 24px 40px;max-width:948px}
.page-hero .eyebrow{font-size:19px;color:var(--accent);font-weight:700;margin-bottom:8px}
.page-hero h1{font-size:clamp(34px,4vw,50px)}
.page-hero .lead{margin-top:18px;color:#3a4558}
.checks{list-style:none;display:flex;flex-wrap:wrap;gap:10px 26px;padding:0;font-size:var(--small);font-weight:700;color:var(--navy)}
.checks li::before{content:"";display:inline-block;width:10px;height:10px;border-radius:50%;background:var(--accent);margin-right:10px;vertical-align:middle}
.hero-actions{display:flex;flex-wrap:wrap;gap:20px 28px;align-items:center;margin-top:26px}
.section.prose{padding-top:40px;padding-bottom:40px}
.prose>*{max-width:900px}
.prose h2{text-align:left;margin-bottom:24px}
.prose h3{font-size:27px;margin:36px auto 8px}
.prose li{margin-bottom:10px}
.prose li::marker{color:var(--accent)}
.prose a:not(.btn){text-decoration-color:var(--accent);text-underline-offset:4px}
.cta{text-align:center}
.cta h2{text-align:center}

/* footer */
.footer{background:var(--navy-dark);color:#cdd8e8;padding:64px 24px 40px;font-size:17px}
.footer a{color:#fff;text-decoration:none}
.footer a:hover{text-decoration:underline}
.footer-inner{max-width:1100px;margin:0 auto;display:flex;flex-wrap:wrap;justify-content:space-between;gap:32px 60px}
.footer-brand b{font-size:26px;color:#fff;letter-spacing:.06em}
.footer-brand p{margin:6px 0 0;line-height:1.6}
.footer-nav{display:grid;grid-template-columns:repeat(2,auto);gap:8px 40px}
.footer-op,.footer-copy{max-width:1100px;margin:36px auto 0;font-size:15px}
.footer-copy{margin-top:4px}
.sticky-cta{display:none}

@media (max-width:1100px){.gnav{display:none}}
@media (max-width:980px){
  .hero{grid-template-columns:1fr;gap:40px;padding-top:40px}
  .features{grid-template-columns:1fr}
  .plans{grid-template-columns:1fr}
  .binary{grid-template-columns:1fr;gap:28px}
}
@media (max-width:820px){
  :root{--body:21px;--small:17px}
  html{scroll-padding-top:72px}
  .header{padding:12px 16px;gap:12px}
  .header.scrolled{padding-top:8px;padding-bottom:8px}
  .brand svg{width:32px}
  .brand-text b{font-size:21px}
  .header-cta,.brand-text small{display:none}
  .section{padding:72px 16px}
  .section h2{margin-bottom:36px}
  .hero{padding:28px 16px 56px}
  .hero h1{font-size:32px}
  .hero-tag{font-size:18px}
  .hero-cta .btn{width:100%}
  .hero-cta{justify-content:center}
  .lab{padding:18px 14px 16px;border-radius:18px}
  .lab-controls{grid-template-columns:1fr}
  .facts{grid-template-columns:1fr;padding:0 16px}
  .facts>div+div{border-left:0;border-top:0}
  .facts>div{padding:18px 4px}
  .facts b{font-size:32px}
  .worries{grid-template-columns:1fr;gap:12px}
  .worries-after{font-size:22px}
  .courses{grid-template-columns:1fr}
  .course-body{padding:22px 20px 26px}
  .course h3{font-size:26px}
  .units{font-size:20px}
  .bits{grid-template-columns:repeat(4,1fr)}
  .binary-out{gap:24px}
  .feature{padding:26px 22px}
  .flow{grid-template-columns:1fr;gap:26px;padding-left:64px}
  .flow::before,.flow::after{top:10px;bottom:10px;left:22px;right:auto;width:2px;height:auto}
  .flow::after{transform:scaleY(0);transform-origin:top}
  .flow.shown::after,.flow:not(.pending)::after{transform:scaleY(1)}
  .flow li::before{position:absolute;left:-64px;top:0}
  .faq-list summary{padding:18px 52px 18px 20px}
  .faq-list summary::after{right:22px}
  .faq-list details p,.faq-a p{padding:0 20px 20px}
  .form{padding:26px 18px}
  .footer{padding-bottom:110px}
  .footer-nav{grid-template-columns:1fr}
  .sticky-cta{display:block;position:fixed;left:12px;right:12px;bottom:calc(12px + env(safe-area-inset-bottom));z-index:30;background:var(--navy);color:#fff;text-align:center;font-weight:700;font-size:19px;padding:14px 16px;border-radius:999px;text-decoration:none;box-shadow:0 10px 28px rgba(20,33,58,.3)}
}