:root{
  --bg:#f7f8f6;--surface:#ffffff;--surface-2:#eef3ef;--text:#14201a;--muted:#5b6b62;
  --line:#dbe3dd;--brand:#006a4e;--brand-2:#00875f;--brand-ink:#ffffff;--accent:#f42a41;
  --ok:#0f8a4a;--bad:#c62828;--warn:#b26a00;--radius:14px;--shadow:0 6px 24px rgba(10,40,25,.08);
  --font:"Inter","Hind Siliguri",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#0e1512;--surface:#151f1a;--surface-2:#1c2a23;--text:#e7efe9;--muted:#9fb1a6;--line:#2a3a32;
  --brand:#21b07f;--brand-2:#2fd196;--brand-ink:#04140d;--shadow:0 6px 24px rgba(0,0,0,.35);}}
:root[data-theme="dark"]{--bg:#0e1512;--surface:#151f1a;--surface-2:#1c2a23;--text:#e7efe9;--muted:#9fb1a6;--line:#2a3a32;
  --brand:#21b07f;--brand-2:#2fd196;--brand-ink:#04140d;--shadow:0 6px 24px rgba(0,0,0,.35);}
*{box-sizing:border-box}
html,body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font);line-height:1.6}
a{color:var(--brand)}
img,svg{max-width:100%}
.container{max-width:1160px;margin:0 auto;padding:0 16px}
header.site{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
header.site .bar{display:flex;align-items:center;gap:12px;height:62px}
.logo{display:flex;align-items:center;gap:8px;font-weight:800;text-decoration:none;color:var(--text);font-size:1.1rem}
.logo .dot{width:30px;height:30px;border-radius:50%;background:var(--brand);position:relative}
.logo .dot::after{content:"";position:absolute;width:12px;height:12px;border-radius:50%;background:var(--accent);left:9px;top:9px}
nav.main{display:flex;gap:4px;margin-left:auto;align-items:center;flex-wrap:wrap}
nav.main a{text-decoration:none;color:var(--text);padding:8px 10px;border-radius:10px;font-weight:500;font-size:.95rem}
nav.main a:hover,nav.main a.active{background:var(--surface-2)}
.btn.menu-btn{display:none;margin-left:auto}
@media (max-width:860px){
  .btn.menu-btn{display:inline-flex}
  nav.main{display:none;position:absolute;top:62px;left:0;right:0;background:var(--surface);flex-direction:column;align-items:stretch;padding:8px 16px;border-bottom:1px solid var(--line)}
  nav.main.open{display:flex}
}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:1px solid var(--line);background:var(--surface);color:var(--text);padding:10px 16px;border-radius:12px;font:inherit;font-weight:600;cursor:pointer;text-decoration:none}
.btn:hover{border-color:var(--brand)}
.btn.primary{background:var(--brand);border-color:var(--brand);color:var(--brand-ink)}
.btn.primary:hover{background:var(--brand-2)}
.btn.small{padding:6px 10px;font-size:.88rem;border-radius:10px}
.btn:disabled{opacity:.55;cursor:not-allowed}
.lang-toggle{font-weight:700}
.hero{padding:56px 0 32px}
.hero h1{font-size:clamp(1.8rem,4.5vw,3rem);line-height:1.15;margin:.2em 0}
.hero p.lead{font-size:1.15rem;color:var(--muted);max-width:640px}
.hero-grid{display:grid;grid-template-columns:1.2fr 1fr;gap:32px;align-items:center}
@media (max-width:860px){.hero-grid{grid-template-columns:1fr}}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow)}
.grid{display:grid;gap:16px}
.g2{grid-template-columns:repeat(2,minmax(0,1fr))}.g3{grid-template-columns:repeat(3,minmax(0,1fr))}.g4{grid-template-columns:repeat(4,minmax(0,1fr))}
@media (max-width:860px){.g3,.g4{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:560px){.g2,.g3,.g4{grid-template-columns:1fr}}
section{padding:36px 0}
h2{font-size:clamp(1.4rem,3vw,2rem);margin:.2em 0 .6em}
.muted{color:var(--muted)}
.pill{display:inline-block;padding:3px 10px;border-radius:99px;background:var(--surface-2);font-size:.82rem;font-weight:600;color:var(--brand)}
.subject-card{display:flex;flex-direction:column;gap:6px;text-decoration:none;color:var(--text);transition:transform .15s}
.subject-card:hover{transform:translateY(-2px);border-color:var(--brand)}
.subject-card .icon{font-size:1.6rem}
.subject-card .meta{font-size:.85rem;color:var(--muted)}
.price{font-size:2rem;font-weight:800}
ul.check{list-style:none;padding:0;margin:0}
ul.check li{padding:4px 0 4px 26px;position:relative}
ul.check li::before{content:"✓";position:absolute;left:0;color:var(--brand);font-weight:800}
footer.site{border-top:1px solid var(--line);padding:24px 0;margin-top:40px;color:var(--muted);font-size:.9rem}
/* quiz */
.q-wrap{max-width:820px;margin:0 auto}
.q-head{display:flex;justify-content:space-between;align-items:center;gap:8px;flex-wrap:wrap;margin-bottom:12px}
.q-text{font-size:1.15rem;font-weight:600;margin:0 0 14px}
.opt{display:flex;gap:10px;align-items:flex-start;width:100%;text-align:left;border:1.5px solid var(--line);background:var(--surface);color:var(--text);padding:12px 14px;border-radius:12px;margin:8px 0;font:inherit;cursor:pointer}
.opt:hover{border-color:var(--brand)}
.opt .k{font-weight:800;min-width:22px;color:var(--muted)}
.opt.correct{border-color:var(--ok);background:color-mix(in srgb,var(--ok) 12%,var(--surface))}
.opt.wrong{border-color:var(--bad);background:color-mix(in srgb,var(--bad) 12%,var(--surface))}
.opt.picked{border-color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,var(--surface))}
.explain{margin-top:12px;padding:14px;border-radius:12px;background:var(--surface-2);border-left:4px solid var(--brand)}
.progress{height:8px;background:var(--surface-2);border-radius:99px;overflow:hidden}
.progress>i{display:block;height:100%;background:var(--brand);width:0}
.timer{font-variant-numeric:tabular-nums;font-weight:800;font-size:1.2rem}
.palette{display:flex;flex-wrap:wrap;gap:6px}
.palette button{width:34px;height:34px;border-radius:8px;border:1px solid var(--line);background:var(--surface);color:var(--text);cursor:pointer;font-weight:600}
.palette button.ans{background:var(--brand);color:var(--brand-ink);border-color:var(--brand)}
.palette button.cur{outline:2px solid var(--accent)}
table.res{width:100%;border-collapse:collapse;font-size:.95rem}
table.res th,table.res td{padding:8px;border-bottom:1px solid var(--line);text-align:left}
.toolbar{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
select,input,textarea{font:inherit;color:var(--text);background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:9px 10px}
textarea{resize:vertical;width:100%}
label.f{display:flex;flex-direction:column;gap:4px;font-weight:600;font-size:.9rem}
.notice{padding:12px 14px;border-radius:12px;background:color-mix(in srgb,var(--warn) 14%,var(--surface));border:1px solid color-mix(in srgb,var(--warn) 40%,var(--line))}
.hidden{display:none!important}
/* tutor */
.tutor-layout{display:grid;grid-template-columns:330px 1fr;gap:16px;padding:16px 0}
@media (max-width:960px){.tutor-layout{grid-template-columns:1fr}}
.avatar-box{position:sticky;top:78px;align-self:start}
@media (max-width:960px){.avatar-box{position:static}.avatar-stage svg{max-width:150px}}
.avatar-stage{background:linear-gradient(160deg,var(--surface-2),var(--surface));border-radius:var(--radius);border:1px solid var(--line);display:flex;justify-content:center;padding:10px;position:relative}
.avatar-stage svg{width:100%;max-width:260px;height:auto}
.photo-av{position:relative;width:100%;max-width:300px;aspect-ratio:1/1;border-radius:22px;overflow:hidden;transition:transform .12s;animation:breathe 5s ease-in-out infinite}
@media (max-width:960px){.photo-av{max-width:170px}}
.photo-av>div{position:absolute}
.pa-base,.pa-jaw{inset:0;background:var(--src) center/cover no-repeat}
.pa-jaw{transition:transform .06s linear;will-change:transform}
.pa-mouth{height:0;opacity:0;border-radius:0 0 50% 50%/0 0 100% 100%;background:radial-gradient(ellipse at 50% 30%,#3a1414 0%,#1e0707 70%);transition:height .06s linear}
@keyframes breathe{0%,100%{filter:brightness(1)}50%{filter:brightness(1.025)}}
.speaking-badge{position:absolute;top:10px;right:10px;font-size:.75rem}
.chat{display:flex;flex-direction:column;gap:12px;min-height:50vh}
.msg{padding:14px 16px;border-radius:14px;max-width:100%;overflow-wrap:anywhere}
.msg.user{background:var(--brand);color:var(--brand-ink);align-self:flex-end;max-width:85%}
.msg.ai{background:var(--surface);border:1px solid var(--line)}
.msg.ai h1,.msg.ai h2,.msg.ai h3{font-size:1.1rem;margin:.6em 0 .3em}
.msg.ai pre{overflow:auto;background:var(--surface-2);padding:10px;border-radius:10px}
.msg.ai table{border-collapse:collapse}.msg.ai td,.msg.ai th{border:1px solid var(--line);padding:4px 8px}
.board{background:#fffef7;color:#1d2a22;border:2px solid #c9b88a;border-radius:12px;padding:12px;margin:10px 0;overflow:auto;box-shadow:inset 0 0 0 6px #f3ecd6}
.board .board-title{font-weight:800;font-size:.8rem;letter-spacing:.06em;color:#7a6631;text-transform:uppercase;margin-bottom:6px}
.board svg{max-width:100%;height:auto}
.composer{position:sticky;bottom:0;background:var(--bg);padding:10px 0;display:flex;gap:8px;align-items:flex-end}
.composer textarea{min-height:52px;max-height:180px}
.chips{display:flex;gap:6px;flex-wrap:wrap}
.chip{border:1px solid var(--line);background:var(--surface);color:var(--text);padding:6px 10px;border-radius:99px;font:inherit;font-size:.85rem;cursor:pointer}
.chip:hover{border-color:var(--brand)}
.typing{display:inline-flex;gap:4px}.typing i{width:7px;height:7px;border-radius:50%;background:var(--muted);animation:b 1s infinite}
.typing i:nth-child(2){animation-delay:.15s}.typing i:nth-child(3){animation-delay:.3s}
@keyframes b{0%,100%{opacity:.25}50%{opacity:1}}
.compare td:last-child{font-weight:700}

/* dropdown menus */
.dd{position:relative}
.dd-btn{font:inherit;font-weight:500;font-size:.95rem;background:none;border:0;color:var(--text);padding:8px 10px;border-radius:10px;cursor:pointer}
.dd-btn:hover,.dd.active>.dd-btn{background:var(--surface-2)}
.dd-menu{display:none;position:absolute;top:100%;left:0;min-width:190px;background:var(--surface);border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow);padding:6px;z-index:30}
.dd.open .dd-menu{display:flex;flex-direction:column}
.dd-menu a{padding:8px 10px}
@media (max-width:860px){.dd-menu{position:static;box-shadow:none;border:0;padding:0 0 0 12px}.dd-btn{width:100%;text-align:left}}
.foot-links{display:flex;flex-wrap:wrap;gap:6px 14px;margin-bottom:10px}
.foot-links a{color:var(--muted);text-decoration:none}.foot-links a:hover{color:var(--brand)}
.mode-toggle{display:inline-flex;border:1px solid var(--line);border-radius:10px;overflow:hidden}
.mode-toggle button{border:0;background:var(--surface);color:var(--text);padding:7px 12px;font:inherit;cursor:pointer}
.mode-toggle button.on{background:var(--brand);color:var(--brand-ink)}
.exam-card{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap}
@media print{header.site,footer.site,.no-print{display:none!important}body{background:#fff;color:#000}.card{box-shadow:none;border:0}}

/* ===== Vibrant theme (v2) ===== */
:root{--grad:linear-gradient(135deg,#006a4e 0%,#00a86b 55%,#2fd196 100%);--grad-red:linear-gradient(135deg,#f42a41,#ff6b5b);--glow:0 10px 30px rgba(0,106,78,.25)}
body{font-family:"Inter","Hind Siliguri",system-ui,sans-serif}
h1,h2,h3{letter-spacing:-.01em}
.btn{transition:transform .15s,box-shadow .2s,background .2s}
.btn:hover{transform:translateY(-1px)}
.btn.primary{background:var(--grad);border:0;box-shadow:var(--glow)}
.btn.pill{border-radius:999px;padding:10px 18px}
.btn.light{background:#fff;color:#0b2a1f;border:0}
.btn.ghost{background:rgba(255,255,255,.12);color:#fff;border:1px solid rgba(255,255,255,.55);backdrop-filter:blur(4px)}
.logo .badge{width:36px;height:36px;border-radius:11px;background:var(--grad);display:grid;place-items:center;color:#fff;font-weight:900;position:relative;box-shadow:var(--glow)}
.logo .badge i{position:absolute;right:-3px;top:-3px;width:12px;height:12px;border-radius:50%;background:#f42a41;border:2px solid var(--bg)}
.logo small{display:block;font-size:.68rem;font-weight:600;color:var(--muted);margin-top:-3px}
.card{animation:rise .5s ease both}
@keyframes rise{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
/* hero slider */
.hero2{position:relative;min-height:min(78vh,640px);color:#fff;overflow:hidden;display:flex;align-items:center}
.hero2 .slide{position:absolute;inset:0;opacity:0;transition:opacity 1.2s ease}
.hero2 .slide.on{opacity:1}
.hero2 .slide .bg{position:absolute;inset:-4%;background-size:cover;background-position:center;animation:kenburns 14s ease-in-out infinite alternate}
.hero2 .slide:nth-child(2n) .bg{animation-name:kenburns2}
@keyframes kenburns{from{transform:scale(1) translate(0,0)}to{transform:scale(1.12) translate(-2%,-2%)}}
@keyframes kenburns2{from{transform:scale(1.12) translate(2%,1%)}to{transform:scale(1) translate(0,0)}}
.hero2 .shade{position:absolute;inset:0;background:linear-gradient(100deg,rgba(0,58,42,.92) 0%,rgba(0,106,78,.78) 42%,rgba(0,106,78,.25) 75%,rgba(244,42,65,.25) 100%)}
.hero2 .inner{position:relative;z-index:2;width:100%}
.hero2 h1{font-size:clamp(2rem,5.2vw,3.6rem);line-height:1.08;margin:.3em 0;max-width:720px;text-shadow:0 2px 20px rgba(0,0,0,.25)}
.hero2 p.lead{color:#e6fff4;font-size:1.15rem;max-width:600px}
.hero2 .kicker{display:inline-block;padding:5px 12px;border-radius:999px;background:rgba(255,255,255,.14);border:1px solid rgba(255,255,255,.35);font-size:.85rem;font-weight:600}
.hero2 .caption{position:absolute;right:16px;bottom:70px;z-index:3;background:rgba(255,255,255,.92);color:#0b2a1f;padding:8px 12px;border-radius:14px;font-size:.85rem;font-weight:600;box-shadow:0 8px 24px rgba(0,0,0,.2);animation:float 4s ease-in-out infinite}
@keyframes float{0%,100%{transform:translateY(0)}50%{transform:translateY(-8px)}}
.hero2 .dots{position:absolute;left:50%;bottom:76px;transform:translateX(-50%);display:flex;gap:6px;z-index:3}
.hero2 .dots button{width:10px;height:10px;border-radius:99px;border:0;background:rgba(255,255,255,.5);cursor:pointer;transition:width .3s}
.hero2 .dots button.on{width:28px;background:#fff}
.hero2 .arrow{position:absolute;top:50%;z-index:3;width:42px;height:42px;border-radius:50%;border:0;background:rgba(255,255,255,.18);color:#fff;font-size:1.3rem;cursor:pointer;backdrop-filter:blur(4px)}
.hero2 .arrow.l{left:12px}.hero2 .arrow.r{right:12px}
@media (max-width:700px){.hero2 .arrow,.hero2 .caption{display:none}}
.fallback-1{background:radial-gradient(circle at 75% 40%,#f42a41 0 12%,transparent 13%),linear-gradient(135deg,#00513b,#00a86b)}
.fallback-2{background:linear-gradient(160deg,#ffb347,#f42a41 45%,#00513b)}
.fallback-3{background:linear-gradient(120deg,#0f3d2e,#3a7d5c,#c9a227)}
.fallback-4{background:radial-gradient(circle at 50% 35%,#f42a41 0 14%,transparent 15%),linear-gradient(180deg,#fff2e6,#ffd6c9 50%,#00513b)}
.fallback-5{background:linear-gradient(135deg,#1d2b64,#00a86b)}
/* stats overlapping hero */
.stats{position:relative;z-index:5;margin-top:-52px}
.stat{display:flex;gap:12px;align-items:center;padding:16px}
.stat .ic{width:46px;height:46px;border-radius:14px;display:grid;place-items:center;font-size:1.4rem;background:var(--surface-2)}
.stat b{font-size:1.6rem;line-height:1}
/* reveal on scroll */
.reveal{opacity:0;transform:translateY(24px);transition:opacity .7s ease,transform .7s ease}
.reveal.in{opacity:1;transform:none}
/* photo feature cards */
.pcard{padding:0;overflow:hidden;display:flex;flex-direction:column;text-decoration:none;color:var(--text);transition:transform .25s,box-shadow .25s}
.pcard:hover{transform:translateY(-4px);box-shadow:0 18px 40px rgba(0,60,40,.18)}
.pcard .ph{aspect-ratio:16/10;background-size:cover;background-position:center;position:relative;overflow:hidden}
.pcard .ph::after{content:"";position:absolute;left:0;right:0;bottom:0;height:4px;background:var(--grad)}
.pcard:nth-child(3n+2) .ph::after{background:var(--grad-red)}
.pcard .ph .zoom{position:absolute;inset:0;background:inherit;background-size:cover;transition:transform 6s ease}
.pcard:hover .ph .zoom{transform:scale(1.1)}
.pcard .tx{padding:16px 18px}
.pcard h3{margin:.1em 0 .3em;font-size:1.1rem}
/* subject marquee */
.marquee{overflow:hidden;white-space:nowrap;padding:14px 0;background:var(--grad);color:#fff}
.marquee .track{display:inline-flex;gap:34px;animation:scroll 40s linear infinite;font-weight:700}
@keyframes scroll{from{transform:translateX(0)}to{transform:translateX(-50%)}}
.section-title{text-align:center;max-width:720px;margin:0 auto 22px}
.section-title .eyebrow{color:#f42a41;font-weight:800;letter-spacing:.08em;text-transform:uppercase;font-size:.8rem}
.band{background:linear-gradient(180deg,var(--surface-2),var(--bg))}
.cta-band{background:var(--grad);color:#fff;border-radius:24px;padding:34px;display:flex;justify-content:space-between;align-items:center;gap:16px;flex-wrap:wrap;box-shadow:var(--glow)}
@media (prefers-reduced-motion:reduce){.hero2 .slide .bg,.marquee .track,.hero2 .caption{animation:none}.reveal{opacity:1;transform:none}}