@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@400;500;600;700;800&display=swap');
:root{--blue:#1769f5;--ink:#10234c;--muted:#64748b;--line:#e6eef8;--soft:#f5f9ff}*{box-sizing:border-box}body{margin:0;font-family:'Be Vietnam Pro',Arial,sans-serif;background:#f7fbff;color:var(--ink)}a{text-decoration:none;color:inherit}.container{width:min(1440px,calc(100% - 48px));margin:auto}.site-header{height:78px;background:#fff;border-bottom:1px solid #edf2f7;display:flex;align-items:center;position:sticky;top:0;z-index:30}.nav{display:flex;align-items:center;gap:28px}.brand{display:flex;align-items:center;gap:10px;min-width:240px}.brand-mark{width:42px;height:42px;border-radius:13px;background:linear-gradient(135deg,#2ed9b4,#1769f5);display:grid;place-items:center;color:#fff;font-size:22px;font-weight:800;box-shadow:0 8px 20px #1769f533}.brand-title{font-size:24px;font-weight:800;letter-spacing:-1px}.brand-title span{color:var(--blue)}.brand-sub{font-size:11px;color:#52709a}.nav-links{display:flex;gap:6px;align-items:center;flex:1}.nav-links a{padding:11px 16px;border-radius:24px;font-size:14px;color:#233c67;white-space:nowrap}.nav-links a:hover,.nav-links .is-active{background:#e8f2ff;color:var(--blue);font-weight:700}.search{height:42px;width:270px;border-radius:22px;background:#f2f6fb;display:flex;align-items:center;gap:9px;padding:0 16px;color:#7890b1}.search input{border:0;outline:0;background:transparent;width:100%;font:inherit;color:var(--ink)}.avatar{width:40px;height:40px;border-radius:50%;display:grid;place-items:center;background:linear-gradient(135deg,#ffd88c,#ff8b62);font-size:20px}.user{display:flex;align-items:center;gap:9px;font-size:12px}.user strong{display:block;font-size:13px}.hero{margin-top:18px;border-radius:30px;overflow:hidden;background:linear-gradient(120deg,#e8f5ff,#dbeafe 55%,#effcff);min-height:350px;position:relative}.hero:after{content:'△  a² + b² = c²  ◇';position:absolute;right:5%;top:18%;font-size:34px;color:#1875dd38;letter-spacing:14px;transform:rotate(-10deg)}.hero-grid{display:grid;grid-template-columns:1.1fr .9fr;align-items:center;min-height:350px;padding:44px 58px;position:relative;z-index:1}.eyebrow{color:var(--blue);font-weight:700;letter-spacing:.04em}.hero h1{font-size:50px;line-height:1.12;letter-spacing:-2px;margin:12px 0}.hero h1 span{color:var(--blue)}.hero p{font-size:17px;line-height:1.6;color:#365175;max-width:610px}.hero-actions{display:flex;gap:12px;margin-top:26px}.btn{border:0;border-radius:14px;padding:13px 21px;font:600 14px inherit;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:8px}.btn-primary{background:var(--blue);color:white;box-shadow:0 8px 20px #1769f52d}.btn-secondary{background:#fff;color:var(--blue);border:1px solid #dbeafe}.btn-ghost{background:#eef6ff;color:var(--blue)}.hero-visual{height:280px;display:flex;align-items:center;justify-content:center}.hero-orb{width:240px;height:240px;border-radius:50%;background:radial-gradient(circle at 35% 30%,#fff 0 8%,#8cd7ff 25%,#1769f5 65%,#0e3f9f 100%);box-shadow:0 28px 40px #1769f540;position:relative}.hero-orb:before{content:'∑';position:absolute;color:white;font-size:100px;font-weight:800;left:70px;top:46px;transform:rotate(-12deg)}.section{padding:28px 0}.section-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:15px}.section-head h2{font-size:22px;margin:0}.section-head a{color:var(--blue);font-size:13px;font-weight:700}.grid{display:grid;gap:16px}.grid-3{grid-template-columns:repeat(3,1fr)}.grid-4{grid-template-columns:repeat(4,1fr)}.card{background:#fff;border:1px solid var(--line);border-radius:20px;padding:18px;box-shadow:0 8px 22px #163b6810}.feature-card{display:grid;grid-template-columns:160px 1fr;gap:16px;align-items:center}.thumb{height:112px;border-radius:14px;background:#e7f2ff center/cover;overflow:hidden}.thumb img{width:100%;height:100%;object-fit:cover}.tag{display:inline-flex;padding:5px 9px;border-radius:9px;background:#e7f1ff;color:var(--blue);font-size:11px;font-weight:700}.muted{color:var(--muted);font-size:13px;line-height:1.55}.progress{height:8px;background:#e8f0fa;border-radius:9px;overflow:hidden}.progress>i{display:block;height:100%;background:linear-gradient(90deg,#24c99a,#1769f5);border-radius:9px}.stat{display:flex;gap:13px;align-items:center}.stat-icon{width:44px;height:44px;border-radius:13px;background:#eaf3ff;display:grid;place-items:center;color:var(--blue);font-size:20px}.stat strong{font-size:22px;display:block}.stat small{color:var(--muted)}.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:15px}.module-card{min-height:150px;background:linear-gradient(135deg,#eff7ff,#fff);border-radius:20px;padding:20px;border:1px solid #deebfa}.module-card.purple{background:linear-gradient(135deg,#f8f1ff,#fff)}.module-card.green{background:linear-gradient(135deg,#effcf7,#fff)}.module-card.orange{background:linear-gradient(135deg,#fff9eb,#fff)}.module-card h3{margin:12px 0 5px}.pill{font-size:12px;color:#547096}.lesson-layout{display:grid;grid-template-columns:minmax(0,1fr) 360px;gap:22px;margin-top:24px}.breadcrumb{font-size:13px;color:#6682a7;margin:18px 0}.lesson-video{aspect-ratio:16/9;background:#061a30;border-radius:20px;overflow:hidden}.lesson-video iframe{width:100%;height:100%;border:0}.lesson-title{font-size:34px;line-height:1.18;margin:10px 0}.lesson-meta{display:flex;flex-wrap:wrap;gap:20px;color:#6380a8;font-size:13px}.tabs{display:flex;gap:6px;border-bottom:1px solid var(--line);margin-top:20px}.tabs a{padding:13px 18px;color:#58749a;font-size:14px}.tabs a.active{color:var(--blue);border-bottom:3px solid var(--blue);font-weight:700}.lesson-copy{font-size:16px;line-height:1.75}.formula{font-size:30px;color:var(--blue);background:#eff7ff;border-radius:14px;padding:14px;text-align:center;margin:18px 0;font-weight:700}.side-title{display:flex;justify-content:space-between;align-items:center}.side-title h3{margin:0}.lesson-list{margin-top:12px}.lesson-row{display:flex;gap:12px;padding:13px 8px;border-top:1px solid #edf2f7;align-items:center;font-size:13px}.lesson-row.current{background:#eaf3ff;border-radius:12px;color:var(--blue);font-weight:700}.check{width:23px;height:23px;border-radius:50%;display:grid;place-items:center;background:#dff8ed;color:#0ca66e;font-size:12px}.check.pending{background:#edf3fb;color:#7b93b1}.dashboard-hero{padding:28px 0 20px;background:linear-gradient(120deg,#e8f5ff,#f4f0ff);border-radius:0 0 30px 30px}.dashboard-layout{display:grid;grid-template-columns:1.2fr .8fr;gap:18px}.chart{height:220px;display:flex;align-items:end;gap:16px;padding:20px 12px 32px;border-bottom:1px solid var(--line)}.bar{width:34px;background:linear-gradient(#4aa7ff,#1769f5);border-radius:9px 9px 2px 2px;position:relative}.bar small{position:absolute;top:100%;margin-top:8px;left:2px;color:#7a91ad;font-size:11px}.admin-shell{display:grid;grid-template-columns:240px 1fr;min-height:calc(100vh - 78px)}.admin-sidebar{background:#0d234d;color:#d7e6ff;padding:22px 14px}.admin-sidebar .brand-title{color:#fff}.admin-sidebar a{display:block;padding:12px 14px;border-radius:10px;margin:4px 0;color:#c0d2ed;font-size:14px}.admin-sidebar a:hover,.admin-sidebar a.is-active{background:#1a4e9f;color:#fff}.admin-main{padding:30px}.admin-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:25px}.table-wrap{overflow:auto}.table{width:100%;border-collapse:collapse;font-size:13px}.table th,.table td{text-align:left;padding:13px 12px;border-bottom:1px solid var(--line)}.table th{color:#637d9e;font-size:12px}.badge{padding:5px 9px;border-radius:8px;background:#e6f8f0;color:#14845c;font-size:11px;font-weight:700}.form-card{max-width:520px;margin:50px auto}.field{margin-bottom:15px}.field label{display:block;font-size:13px;font-weight:700;margin-bottom:7px}.field input,.field select,.field textarea{width:100%;border:1px solid #d9e6f4;border-radius:11px;padding:12px;font:inherit;outline:0;background:white}.field input:focus,.field textarea:focus{border-color:var(--blue);box-shadow:0 0 0 3px #1769f51c}.alert{padding:12px 14px;border-radius:12px;margin:12px 0;font-size:13px}.alert.error{background:#fff0f0;color:#b33939}.alert.success{background:#eafbf3;color:#14744e}.empty{padding:35px;text-align:center;color:#6f87a5}.mobile-menu{display:none}@media(max-width:1100px){.nav-links{gap:0}.nav-links a{padding:10px}.search{width:190px}.hero h1{font-size:40px}.grid-4{grid-template-columns:repeat(2,1fr)}}@media(max-width:800px){.container{width:min(100% - 28px,600px)}.site-header{height:66px}.brand{min-width:0}.brand-title{font-size:20px}.brand-sub,.nav-links,.user span,.search{display:none}.mobile-menu{display:block;margin-left:auto}.hero-grid{grid-template-columns:1fr;padding:30px 24px}.hero h1{font-size:36px}.hero-visual{display:none}.stats,.grid-3,.grid-4,.dashboard-layout{grid-template-columns:1fr}.feature-card{grid-template-columns:110px 1fr}.lesson-layout{grid-template-columns:1fr}.lesson-title{font-size:28px}.admin-shell{grid-template-columns:1fr}.admin-sidebar{display:none}.admin-main{padding:20px 14px}}