*,*::before,*::after{box-sizing:border-box}
html,body{margin:0;padding:0;overflow-x:hidden}
:root{
  --charcoal:#2B2D42;
  --ink:#1A1A2A;
  --muted:#6B6B78;
  --faint:#9A9BAD;
  --coral:#D4614B;
  --coral-soft:#FAEAE7;
  --paper:#FBF9F4;
  --surface:#FFFFFF;
  --rule:#E5E2E2;
  --rule-soft:#F4F1EC;
  --green:#2E8B57;
  --yellow:#FFF2DB;
  --maxw:1120px;
  --contentw:760px;
}
body{
  background:var(--paper);
  color:var(--ink);
  font-family:'Hind Siliguri','Inter Tight',system-ui,sans-serif;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
}
a{color:var(--coral);text-decoration:none}
a:hover{text-decoration:underline}
::selection{background:var(--coral-soft);color:var(--coral)}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 56px}
.nav{position:sticky;top:0;z-index:50;background:var(--charcoal)}
.nav-inner{height:64px;display:flex;align-items:center;gap:40px;position:relative}
.logo{font-family:'Inter Tight',sans-serif;font-size:18px;font-weight:700;color:#fff;letter-spacing:-.01em;text-decoration:none;white-space:nowrap;flex-shrink:0}
.logo span{color:var(--coral)}
.nav-links{display:flex;align-items:center;gap:28px;list-style:none;margin:0 0 0 8px;padding:0}
.nav-links>li{display:flex;align-items:center}
.nav-links>li>a{display:flex;align-items:center;min-height:64px}
.nav-links a,.nav-menu-btn{font-family:'Inter Tight',sans-serif;font-size:14px;font-weight:500;color:rgba(255,255,255,.7);text-decoration:none;transition:color .15s ease}
.nav-links a:hover,.nav-links a.active,.nav-menu-btn:hover,.guide-menu:focus-within .nav-menu-btn,.guide-menu:hover .nav-menu-btn{color:#fff;text-decoration:none}
.nav-right{margin-left:auto;display:flex;gap:12px;align-items:center}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:40px;padding:8px 18px;border-radius:8px;border:1px solid transparent;font-family:'Hind Siliguri','Inter Tight',sans-serif;font-size:14px;font-weight:700;text-decoration:none;cursor:pointer;transition:background .15s ease,border-color .15s ease,color .15s ease}
.btn-primary{background:var(--coral);color:#fff}
.btn-primary:hover{background:#BF5340;color:#fff;text-decoration:none}
.btn-ghost{background:transparent;color:rgba(255,255,255,.85);border-color:rgba(255,255,255,.28)}
.btn-ghost:hover{border-color:#fff;color:#fff;text-decoration:none}
.guide-menu{position:relative}
.nav-menu-btn{display:flex;align-items:center;gap:6px;height:64px;padding:0;background:transparent;border:none;cursor:pointer}
.nav-menu-btn::after{content:"";width:6px;height:6px;border-right:1.5px solid currentColor;border-bottom:1.5px solid currentColor;transform:rotate(45deg);margin-top:-3px;opacity:.8}
.guide-mega{
  display:none;
  position:absolute;
  top:100%;
  left:-120px;
  width:min(860px,calc(100vw - 32px));
  background:var(--surface);
  border:1px solid var(--rule);
  border-radius:12px;
  box-shadow:0 18px 44px rgba(0,0,0,.18);
  padding:18px;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:12px;
  max-height:calc(100vh - 80px);
  overflow:auto;
}
.guide-menu:hover .guide-mega,.guide-menu:focus-within .guide-mega,.guide-menu.open .guide-mega{display:grid}
.guide-group{padding:14px;border-radius:8px;background:var(--paper);border:1px solid var(--rule-soft)}
.guide-group strong{display:block;font-family:'Hind Siliguri','Inter Tight',sans-serif;font-size:14px;line-height:1.35;color:var(--charcoal);margin-bottom:8px}
.guide-group a,.guide-group span{display:block;font-family:'Hind Siliguri','Inter Tight',sans-serif;font-size:13px;line-height:1.55;color:var(--muted);padding:3px 0;text-decoration:none}
.guide-group a:hover{color:var(--coral);text-decoration:none}
.guide-group .live{color:var(--coral);font-weight:700}
.guide-group.listening-group,.guide-group.reading-group,.guide-group.writing-group,.guide-group.speaking-group,.guide-group.band-score-group,.guide-group.requirements-group,.guide-group.exam-group{grid-row:span 2}
.guide-group.listening-group a,.guide-group.reading-group a,.guide-group.writing-group a,.guide-group.speaking-group a,.guide-group.band-score-group a,.guide-group.requirements-group a,.guide-group.exam-group a{padding:2px 0}
.hero{padding:64px 0 40px;border-bottom:1px solid var(--rule)}
.eyebrow{display:inline-flex;align-items:center;gap:10px;font-family:'Inter Tight','Hind Siliguri',sans-serif;font-size:11px;font-weight:800;color:var(--coral);letter-spacing:.08em;text-transform:uppercase}
.eyebrow .dot{width:5px;height:5px;border-radius:50%;background:var(--coral)}
h1,h2,h3,h4{font-family:'Hind Siliguri','Inter Tight',system-ui,sans-serif;color:var(--charcoal);letter-spacing:0}
h1{margin:18px 0 0;max-width:900px;font-size:clamp(32px,4.4vw,52px);line-height:1.35;font-weight:700}
.lede{max-width:760px;margin:22px 0 0;font-size:18px;line-height:1.85;color:var(--ink)}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:24px}
.hero-meta{display:flex;gap:10px;flex-wrap:wrap;margin-top:22px}
.pill{display:inline-flex;align-items:center;gap:8px;padding:7px 12px;border:1px solid var(--rule);border-radius:999px;background:var(--surface);font-size:13px;font-weight:700;color:var(--ink)}
.layout{display:grid;grid-template-columns:minmax(0,1fr) 280px;gap:40px;padding:40px 0 64px;align-items:start}
.article{max-width:var(--contentw)}
.article h2{margin:48px 0 14px;font-size:28px;line-height:1.45}
.article h3{margin:28px 0 10px;font-size:20px;line-height:1.45}
.article p{margin:0 0 16px;font-size:16px}
.article ul,.article ol{margin:0 0 20px;padding-left:24px}
.article li{margin:8px 0;font-size:16px}
.toc{position:sticky;top:88px;background:var(--surface);border:1px solid var(--rule);border-radius:12px;padding:18px}
.toc strong{display:block;margin-bottom:10px;font-size:14px;color:var(--charcoal)}
.toc a{display:block;padding:7px 0;font-size:13px;font-weight:600;color:var(--muted);text-decoration:none;border-top:1px solid var(--rule-soft)}
.toc a:first-of-type{border-top:none}
.toc a:hover{color:var(--coral)}
.guide-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px;margin:24px 0}
.guide-card{display:block;background:var(--surface);border:1px solid var(--rule);border-radius:12px;padding:20px;text-decoration:none;color:var(--ink);box-shadow:0 1px 3px rgba(0,0,0,.04)}
.guide-card:hover{border-color:var(--coral);text-decoration:none}
.guide-card strong{display:block;color:var(--charcoal);font-size:18px;margin-bottom:8px}
.guide-card span{display:block;color:var(--muted);font-size:14px;line-height:1.65}
.callout,.teacher,.mistake,.example,.practice,.source-box{border-radius:12px;border:1px solid var(--rule);padding:20px;margin:24px 0;background:var(--surface)}
.teacher{border-left:4px solid var(--coral);background:linear-gradient(90deg,rgba(212,97,75,.08),#fff)}
.mistake{border-left:4px solid #B45309;background:#FFFBEB}
.example{border-left:4px solid var(--green);background:#F6FFF9}
.practice{border-left:4px solid var(--charcoal)}
.source-box{background:var(--rule-soft)}
.label{display:inline-flex;align-items:center;gap:8px;margin-bottom:10px;font-size:12px;font-weight:800;color:var(--coral);letter-spacing:.04em}
.bad-good{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:16px 0}
.bad,.good{border:1px solid var(--rule);border-radius:8px;padding:14px;background:#fff}
.bad strong,.good strong{display:block;margin-bottom:8px;color:var(--charcoal)}
.bad{background:#FFF7F5}
.good{background:#F6FFF9}
.table-wrap{max-width:100%;overflow-x:auto;margin:20px 0;border:1px solid var(--rule);border-radius:12px;background:var(--surface)}
table{width:100%;border-collapse:collapse;min-width:620px}
th,td{padding:12px 14px;border-bottom:1px solid var(--rule);text-align:left;vertical-align:top;font-size:15px}
th{background:var(--rule-soft);font-weight:800;color:var(--charcoal)}
tr:last-child td{border-bottom:none}
.quiz-options{display:grid;gap:10px;margin-top:12px}
.quiz-options button,.reveal-btn{width:100%;text-align:left;border:1px solid var(--rule);background:#fff;border-radius:8px;padding:12px 14px;font-family:'Hind Siliguri','Inter Tight',sans-serif;font-size:15px;line-height:1.5;cursor:pointer}
.quiz-options button:hover,.reveal-btn:hover{border-color:var(--coral)}
.quiz-options button.correct{border-color:var(--green);background:#F0FFF4}
.quiz-options button.wrong{border-color:var(--coral);background:#FFF7F5}
.answer{display:none;margin-top:12px;border:1px solid var(--rule);border-radius:8px;background:#fff;padding:14px}
.answer.open{display:block}
.mini-check{display:grid;gap:10px;margin:14px 0}
.mini-check label{display:flex;gap:10px;align-items:flex-start;background:#fff;border:1px solid var(--rule);border-radius:8px;padding:10px 12px;font-size:15px}
.mini-check input{margin-top:6px}
.band-mini{border:1px solid var(--rule);border-radius:12px;background:var(--surface);padding:20px;margin:24px 0}
.band-fields{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin:14px 0}
.band-field label,.band-fields label{display:block;font-size:13px;font-weight:800;color:var(--charcoal);margin-bottom:6px}
.band-field input,.band-fields input,.band-fields select{width:100%;height:42px;border:1px solid var(--rule);border-radius:8px;padding:0 10px;font-family:'Inter Tight','Hind Siliguri',sans-serif;font-size:15px;font-weight:700;color:var(--ink);background:#fff}
.band-result{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:14px 0}
.band-result div{border:1px solid var(--rule-soft);border-radius:8px;background:var(--paper);padding:12px}
.band-result span{display:block;font-size:12px;font-weight:800;color:var(--muted);margin-bottom:4px}
.band-result strong{font-family:'Inter Tight','Hind Siliguri',sans-serif;font-size:28px;line-height:1;color:var(--coral)}
.band-rule{margin:8px 0 0;color:var(--muted);font-size:14px}
.cta-band{margin-top:48px;padding:28px;border-radius:12px;background:var(--charcoal);color:#fff}
.cta-band h2{margin:0 0 10px;color:#fff}
.cta-band p{color:rgba(255,255,255,.82)}
.cta-band .btn{margin-top:8px}
details{border:1px solid var(--rule);border-radius:8px;background:#fff;margin:10px 0;padding:0 14px}
summary{cursor:pointer;padding:14px 0;font-weight:800;color:var(--charcoal)}
details p{padding-bottom:14px}
footer{border-top:1px solid var(--rule);padding:28px 0;color:var(--muted);font-size:13px}
.bn-term{font-family:'Inter Tight','Hind Siliguri',sans-serif;font-weight:700;color:var(--charcoal)}
@media(max-width:900px){
  .wrap{padding:0 24px}
  .nav-inner{gap:14px}
  .nav-links{gap:16px;margin-left:0;overflow-x:auto;min-width:0}
  .nav-links::-webkit-scrollbar{display:none}
  .nav-links>li:not(.guide-menu){display:none}
  .guide-mega{left:0;width:calc(100vw - 48px);grid-template-columns:1fr;max-height:70vh;overflow:auto}
  .layout{display:block;padding-top:28px}
  .toc{position:static;margin-bottom:28px}
  .article{max-width:none}
  .guide-grid,.bad-good,.band-fields,.band-result{grid-template-columns:1fr}
}
@media(max-width:520px){
  .wrap{padding:0 16px}
  .nav-right .btn-ghost{display:none}
  h1{font-size:30px}
  .hero{padding:40px 0 32px}
  .article h2{font-size:24px;margin-top:40px}
  .btn{width:100%}
  .hero-actions .btn{width:100%}
}