:root{
  --bg:#fbf8f3;
  --bg-soft:#f6f0e9;
  --paper:#ffffff;
  --ink:#121212;
  --muted:#6b655f;
  --line:#dfd8d0;
  --orange:#f4512a;
  --orange-dark:#d93f1c;
  --orange-soft:#fde9e1;
  --orange-pale:#fff3ed;
  --green:#2b8a62;
  --shadow:0 18px 55px rgba(28,21,15,.09);
  --shadow-sm:0 10px 30px rgba(28,21,15,.07);
  --radius-xl:30px;
  --radius-lg:22px;
  --radius-md:16px;
  --container:1220px;
  --nav-h:100px;
  --ease:cubic-bezier(.2,.8,.2,1);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:110px}
body{margin:0;background:var(--bg);color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;font-size:16px;line-height:1.68;-webkit-font-smoothing:antialiased}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit}
button{color:inherit}
.container{width:min(calc(100% - 44px),var(--container));margin-inline:auto}
.section{padding:112px 0}
.section-pad-lg{padding:122px 0 105px}
.orange{color:var(--orange)}
.eyebrow{display:flex;align-items:center;gap:12px;margin:0 0 20px;color:var(--orange-dark);font-size:.78rem;line-height:1.2;font-weight:850;letter-spacing:.16em;text-transform:uppercase}
.eyebrow::before{content:"";width:26px;height:2px;background:currentColor;border-radius:99px;flex:none}
h1,h2,h3,p{margin-top:0}
h1,h2,h3{letter-spacing:-.045em;line-height:1.02}
h1{font-size:clamp(4rem,7vw,7.2rem);margin-bottom:28px;font-weight:900}
h2{font-size:clamp(2.65rem,4.4vw,4.8rem);margin-bottom:0;font-weight:880}
h3{font-size:1.45rem;line-height:1.18;margin-bottom:14px}
.lead{font-size:1.12rem;line-height:1.75;color:var(--muted);max-width:650px}
.section-head{display:grid;grid-template-columns:1.05fr .75fr;gap:72px;align-items:end;margin-bottom:58px}
.section-head.compact{margin-bottom:48px}
.section-head .lead{margin-bottom:2px}
.reveal{opacity:0;transform:translateY(18px);transition:opacity .7s var(--ease),transform .7s var(--ease)}
.reveal.is-visible{opacity:1;transform:none}
::selection{background:var(--orange);color:#fff}
[hidden]{display:none!important}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:54px;padding:0 24px;border:1px solid transparent;border-radius:999px;font-weight:800;transition:transform .2s var(--ease),box-shadow .2s var(--ease),background .2s var(--ease),border-color .2s var(--ease)}
.btn:hover{transform:translateY(-2px)}
.btn-primary{background:var(--orange);color:#fff;box-shadow:0 12px 28px rgba(244,81,42,.22)}
.btn-primary:hover{background:var(--orange-dark);box-shadow:0 16px 36px rgba(244,81,42,.28)}
.btn-ghost{border-color:var(--line);background:rgba(255,255,255,.62)}
.btn-ghost:hover{background:#fff;border-color:#cfc5bb}
.btn-dark{background:var(--ink);color:#fff;white-space:nowrap}
.site-nav{position:sticky;top:0;z-index:100;background:rgba(251,248,243,.9);border-bottom:1px solid rgba(56,44,35,.09);backdrop-filter:blur(16px)}
.nav-inner{height:var(--nav-h);display:flex;align-items:center;justify-content:space-between;gap:28px}
.brand{width:132px;display:flex;align-items:center;align-self:stretch;padding:4px 0}
.brand img{height:88px;width:auto;object-fit:contain}
.nav-links{display:flex;align-items:center;gap:30px;font-size:.94rem;font-weight:700}
.nav-links>a,.nav-dropdown>summary{transition:color .2s ease;cursor:pointer;list-style:none;white-space:nowrap}
.nav-links>a:hover,.nav-dropdown>summary:hover{color:var(--orange)}
.nav-links>a.is-active{color:var(--orange-dark)}
.nav-links>a.is-active::after{content:"";display:block;height:2px;border-radius:999px;background:var(--orange);margin-top:2px}
.nav-dropdown{position:relative}
.nav-dropdown summary::-webkit-details-marker{display:none}
.nav-dropdown-panel{position:absolute;right:-180px;top:calc(100% + 22px);width:520px;padding:22px;background:#fff;border:1px solid var(--line);border-radius:20px;box-shadow:var(--shadow);display:grid;grid-template-columns:1fr 1fr;gap:18px}
.nav-product-group{padding:7px}
.nav-product-group p{font-size:.75rem;font-weight:900;letter-spacing:.14em;color:var(--orange);margin:0 0 8px;text-transform:uppercase}
.nav-product-group a{display:flex;justify-content:space-between;padding:9px 10px;border-radius:10px;font-weight:750}
.nav-product-group a:hover{background:var(--orange-pale);color:var(--orange-dark)}
.btn-nav{min-height:48px;padding-inline:21px;color:#fff!important}
.nav-toggle{display:none;background:none;border:0;padding:8px;cursor:pointer}
.nav-toggle span{display:block;width:26px;height:2px;background:var(--ink);margin:6px 0}
.score-badges{display:grid;grid-template-columns:1fr 1fr;gap:12px;width:100%}
.score-badge{min-width:0;padding:13px 18px;background:var(--orange);color:var(--ink);border:1px solid rgba(17,17,17,.08);border-radius:14px;display:flex;align-items:baseline;justify-content:center;gap:8px;box-shadow:0 10px 24px rgba(244,81,42,.18)}
.score-badge small{font-size:.66rem;font-weight:950;letter-spacing:.09em;color:rgba(17,17,17,.72)}
.score-badge b{font-size:1.35rem;line-height:1}
.video-modal{width:min(92vw,900px);padding:0;border:0;border-radius:20px;background:#0f0f0f;color:#fff;box-shadow:0 30px 90px rgba(0,0,0,.38)}
.video-modal::backdrop{background:rgba(0,0,0,.68);backdrop-filter:blur(5px)}
.video-modal-inner{position:relative;padding:22px}
.video-modal-inner p{padding-right:48px;font-weight:800;margin-bottom:16px}
.video-modal video{width:100%;max-height:75vh;background:#000;border-radius:14px}
.modal-close{position:absolute;right:14px;top:10px;border:0;background:transparent;color:#fff;font-size:2rem;cursor:pointer}

/* V5 flagship navigation + official-exam visual marks */
.nav-flagship{padding:10px 16px;border:1px solid rgba(244,81,42,.18);border-radius:999px;background:var(--orange-pale);color:var(--ink)!important}
.nav-flagship:hover{background:#ffe1d5!important;color:var(--orange-dark)!important}
.nav-exam-logo{display:block;width:82px;height:25px;object-fit:contain;object-position:left center}.nav-exam-logo.toeic{width:92px}
.partner-row{margin-top:1px;padding-top:15px;border-top:1px solid var(--line);display:flex;align-items:center;justify-content:center;gap:13px;color:var(--ink);font-size:.76rem;font-weight:850;letter-spacing:.02em}
.partner-row img{width:138px;height:auto;display:block}
.exam-tab img{width:78px;height:26px;object-fit:contain}.exam-tab[data-exam-tab="toeic"] img{width:90px}
.skill-icon.brand-skill{width:68px;height:52px;padding:8px;background:#fff;border:1px solid rgba(244,81,42,.16)}
.skill-icon.brand-skill img{width:100%;height:100%;object-fit:contain}.skill-icon.toeic-skill{border-color:rgba(23,100,63,.18)}

/* v6.6: Bài giảng online + Minigame in Hệ thống tự học */
.nav-resource-group{grid-column:1/-1;display:grid;grid-template-columns:1fr 1fr;gap:10px;padding-top:12px;border-top:1px solid var(--line)}
.nav-resource-group a{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px 14px;border-radius:12px;background:#faf7f3;font-weight:750}
.nav-resource-group a:hover,.nav-resource-group a.is-active{background:var(--orange-pale);color:var(--orange-dark)}
.nav-resource-group small{display:block;margin-bottom:2px;color:#8a8179;font-size:.62rem;font-weight:800;letter-spacing:.08em;text-transform:uppercase}
.nav-resource-group strong{font-size:.88rem}.nav-resource-group b{font-size:1rem;color:var(--orange)}
.nav-dropdown>summary.is-active{color:var(--orange-dark)!important}