:root{
  --blue:#0b43c8;--blue2:#072c78;--navy:#061b43;--yellow:#ffd53d;
  --text:#13213c;--muted:#68748a;--bg:#f5f8ff;--card:#fff;--line:#e4eaf5;
  --shadow:0 14px 40px rgba(14,43,92,.10);--radius:20px
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"Hind Siliguri",Arial,sans-serif;color:var(--text);background:var(--bg)}
a{text-decoration:none;color:inherit}
img{max-width:100%;display:block}
.container{width:min(1520px,calc(100% - 40px));margin:auto}
.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.96);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
.nav-wrap{min-height:72px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.brand{display:flex;align-items:center;gap:10px;font-family:Inter,sans-serif}
.brand-mark{display:grid;place-items:center;width:42px;height:42px;border-radius:13px;background:linear-gradient(135deg,#eaf1ff,#fff3bd);font-size:23px}
.brand strong{display:block;font-size:17px;line-height:1}.brand small{font-size:10px;letter-spacing:1.9px;color:var(--blue)}
nav{display:flex;align-items:center;gap:25px;font-weight:600}
nav a:not(.btn):hover{color:var(--blue)}
.nav-toggle{display:none;border:0;background:#edf3ff;padding:10px 12px;border-radius:10px;font-size:20px}
.btn{display:inline-flex;align-items:center;justify-content:center;border-radius:12px;padding:12px 18px;background:linear-gradient(135deg,#1763ef,#073ca9);color:#fff;font-weight:700;box-shadow:0 8px 20px rgba(11,67,200,.18)}
.btn:hover{transform:translateY(-1px)}
.btn-sm{padding:10px 15px}
.btn-outline{background:transparent;border:1px solid rgba(255,255,255,.55);box-shadow:none}
.btn-light{background:white;color:var(--blue)}
.hero{background:radial-gradient(circle at 80% 25%,#315fbd 0,transparent 30%),linear-gradient(120deg,#051d4a,#0b43c8);color:#fff;padding:70px 0 95px}
.hero-grid{display:grid;grid-template-columns:1.05fr .95fr;align-items:center;gap:40px}
.kicker{color:#bcd3ff;font-weight:700;letter-spacing:.6px}
.hero h1{font-size:clamp(38px,5.4vw,70px);line-height:1.08;margin:10px 0 20px}
.hero h1 span{color:var(--yellow)}
.hero p{font-size:19px;line-height:1.7;color:#e0eaff;max-width:640px}
.actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:28px}
.hero-art{position:relative;min-height:370px;display:grid;place-items:center}
.book-stack{width:min(420px,90%);padding:32px;border-radius:34px;background:linear-gradient(145deg,rgba(255,255,255,.17),rgba(255,255,255,.05));border:1px solid rgba(255,255,255,.2);box-shadow:0 30px 80px rgba(0,0,0,.22)}
.book{height:58px;border-radius:8px 15px 15px 8px;margin:10px 0;display:flex;align-items:center;padding:0 18px;font:700 18px Inter;background:white;color:#0b43c8;box-shadow:0 10px 25px rgba(0,0,0,.18)}
.book:nth-child(2){background:#e33b45;color:#fff}.book:nth-child(3){background:#173c78;color:#fff}.book:nth-child(4){background:#ffd53d;color:#13213c}
.section{padding:52px 0}
.section-title{display:flex;align-items:end;justify-content:space-between;gap:15px;margin-bottom:22px}
.section-title h2{margin:0;font-size:28px}.section-title p{margin:4px 0 0;color:var(--muted)}
.link{color:var(--blue);font-weight:700}
.cards{display:grid;grid-template-columns:repeat(5,1fr);gap:14px}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow)}
.category-card .icon{width:52px;height:52px;border-radius:15px;display:grid;place-items:center;background:#edf3ff;font-size:27px;margin-bottom:14px}
.category-card h3{margin:0 0 4px;font-size:17px}.category-card p{margin:0;color:var(--muted);font-size:14px}
.split{display:grid;grid-template-columns:1fr 1fr;gap:20px}
.lecture-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px}
.lecture-card{padding:0;overflow:hidden}
.thumb{height:128px;background:linear-gradient(135deg,#5a311b,#171c4f);color:#fff;display:flex;align-items:center;justify-content:center;text-align:center;padding:18px;font-size:20px;font-weight:700}
.card-body{padding:18px}.meta{display:flex;gap:8px;flex-wrap:wrap;color:var(--muted);font-size:13px}.rating{color:#e7a400}
.badge{display:inline-block;padding:5px 9px;border-radius:999px;background:#eaf8ef;color:#128440;font-size:12px;font-weight:700}.badge.premium{background:#fff0d8;color:#a85b00}
.open-app{margin-top:14px;width:100%}
.quiz-panel{display:grid;gap:12px}
.quiz-item,.list-item{display:flex;align-items:center;justify-content:space-between;gap:12px;background:#fff;border:1px solid var(--line);border-radius:15px;padding:16px}
.quiz-item strong,.list-item strong{display:block}.quiz-item small,.list-item small{color:var(--muted)}
.promo{background:linear-gradient(135deg,#0d4ccb,#6a35cf);color:#fff;padding:26px;border-radius:22px;margin-top:18px}
.promo h3{font-size:26px;margin:0 0 7px}.promo p{color:#e7e6ff}
.footer{background:#061b43;color:#dce8ff;padding:48px 0 20px;margin-top:35px}
.footer-grid{display:grid;grid-template-columns:1.4fr .8fr 1fr;gap:35px}.footer h4{color:#fff;margin-top:0}.footer a{display:block;margin:8px 0;color:#dce8ff}.footer-brand{color:#fff}.footer-bottom{border-top:1px solid rgba(255,255,255,.12);margin-top:30px;padding-top:18px;text-align:center;color:#9fb6dc}
.page-hero{padding:45px 0;background:linear-gradient(135deg,#071f4c,#0b43c8);color:#fff}.page-hero h1{margin:0;font-size:38px}.page-hero p{color:#dce8ff}
.content-list{display:grid;gap:14px}.content-list .list-item{box-shadow:var(--shadow)}
.notice{padding:15px 18px;border-radius:14px;background:#fff9db;border:1px solid #f6e89b;margin:20px 0}
@media(max-width:980px){.cards{grid-template-columns:repeat(3,1fr)}.hero-grid,.split{grid-template-columns:1fr}.hero-art{min-height:280px}.footer-grid{grid-template-columns:1fr 1fr}}
@media(max-width:760px){
  .nav-toggle{display:block}nav{display:none;position:absolute;top:72px;left:16px;right:16px;background:white;padding:18px;border-radius:16px;box-shadow:var(--shadow);flex-direction:column;align-items:stretch}nav.show{display:flex}
  .hero{padding:48px 0 60px}.hero h1{font-size:42px}.hero-art{display:none}.cards{grid-template-columns:repeat(2,1fr)}.lecture-grid{grid-template-columns:1fr}.footer-grid{grid-template-columns:1fr}.section{padding:36px 0}
}
@media(max-width:480px){.cards{grid-template-columns:1fr}.container{width:min(100% - 22px,1520px)}.hero h1{font-size:36px}}

.feature-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:14px}
.feature-card{display:flex;flex-direction:column;min-height:180px}
.feature-icon{width:48px;height:48px;border-radius:14px;background:#edf3ff;display:grid;place-items:center;font-size:25px;margin-bottom:12px}
.feature-card h3{margin:0 0 6px}.feature-card p{color:var(--muted);margin:0 0 15px;flex:1}.feature-card .btn{width:100%}
.zone-head{padding:22px;border-radius:22px;background:linear-gradient(135deg,#eef4ff,#fff);border:1px solid var(--line);margin-bottom:16px}
.zone-head h2{margin:0 0 5px}.zone-head p{margin:0;color:var(--muted)}
.rank-preview{counter-reset:rank;display:grid;gap:10px}
.rank-row{display:flex;align-items:center;gap:12px;padding:14px 16px;border:1px solid var(--line);border-radius:14px;background:white}
.rank-row:before{counter-increment:rank;content:"# " counter(rank);font-weight:800;color:var(--blue);min-width:38px}
.rank-user{flex:1}.rank-score{font-weight:800;color:var(--blue)}
.mini-note{font-size:13px;color:var(--muted)}
@media(max-width:1000px){.feature-grid{grid-template-columns:repeat(3,1fr)}}
@media(max-width:760px){.feature-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:480px){.feature-grid{grid-template-columns:1fr}}