:root{
  --indigo:#3538CD; --indigo-600:#4F46E5; --indigo-50:#EEF0FF;
  --coral:#FF6B4A; --coral-600:#F0512B;
  --ink:#0F1222; --muted:#5B6178; --line:#E7E9F3; --bg:#F6F7FB; --white:#fff;
  --ok:#16a34a; --warn:#D97706; --danger:#DC2626;
  --radius:16px; --shadow:0 8px 30px rgba(20,22,50,.08);
}
*{box-sizing:border-box}
body{margin:0;font-family:'Be Vietnam Pro',system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.55;-webkit-font-smoothing:antialiased}
a{color:var(--indigo);text-decoration:none}
img{max-width:100%;display:block}
.container{max-width:1140px;margin:0 auto;padding:0 20px}
.container-sm{max-width:520px;margin:0 auto;padding:0 20px}

/* Navbar */
.nav{background:var(--white);border-bottom:1px solid var(--line);position:sticky;top:0;z-index:50}
.nav-in{display:flex;align-items:center;gap:20px;height:64px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:20px;color:var(--ink)}
.brand .logo{height:40px;width:auto;object-fit:contain}
.nav-links{display:flex;gap:22px;margin-left:8px}
.nav-links a{color:var(--muted);font-weight:600;font-size:15px}
.nav-links a:hover{color:var(--indigo)}
.nav-right{margin-left:auto;display:flex;gap:10px;align-items:center}

/* Buttons */
.btn{display:inline-flex;align-items:center;gap:8px;justify-content:center;border:none;cursor:pointer;
  font-family:inherit;font-weight:700;font-size:15px;padding:11px 20px;border-radius:12px;transition:.18s;text-align:center}
.btn-primary{background:var(--indigo);color:#fff}
.btn-primary:hover{background:var(--indigo-600)}
.btn-coral{background:var(--coral);color:#fff}
.btn-coral:hover{background:var(--coral-600)}
.btn-ghost{background:var(--indigo-50);color:var(--indigo)}
.btn-outline{background:#fff;color:var(--ink);border:1.5px solid var(--line)}
.btn-zalo{background:#0068FF;color:#fff}
.btn-block{width:100%}
.btn-lg{padding:14px 26px;font-size:16px}
.btn-sm{padding:8px 14px;font-size:14px}

/* Cards */
.card{background:var(--white);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow)}
.card-pad{padding:22px}

/* Course grid */
.grid{display:grid;gap:22px}
.grid-3{grid-template-columns:repeat(3,1fr)}
.grid-2{grid-template-columns:repeat(2,1fr)}
.course-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;
  box-shadow:var(--shadow);transition:.2s;display:flex;flex-direction:column}
.course-card:hover{transform:translateY(-4px);box-shadow:0 16px 40px rgba(20,22,50,.13)}
.course-thumb{aspect-ratio:16/9;background:linear-gradient(135deg,var(--indigo),var(--coral));
  display:grid;place-items:center;color:#fff;font-size:40px;font-weight:800}
.course-thumb img{width:100%;height:100%;object-fit:cover}
.course-body{padding:18px;display:flex;flex-direction:column;gap:8px;flex:1}
.course-title{font-weight:800;font-size:18px;margin:0}
.course-sub{color:var(--muted);font-size:14px;margin:0;flex:1}
.course-meta{display:flex;align-items:center;gap:12px;font-size:13px;color:var(--muted);margin-top:4px}
.badge{display:inline-block;padding:4px 10px;border-radius:999px;font-size:12px;font-weight:700}
.badge-indigo{background:var(--indigo-50);color:var(--indigo)}
.badge-coral{background:#FFECE6;color:var(--coral-600)}
.badge-ok{background:#DCFCE7;color:#15803D}
.badge-warn{background:#FEF3C7;color:#B45309}
.badge-muted{background:#EEF0F4;color:#64748B}
.price{font-weight:800;color:var(--coral-600);font-size:18px}
.price-free{color:var(--ok)}

/* Sections / hero */
.page-head{padding:40px 0 10px}
.page-head h1{font-size:32px;margin:0 0 6px}
.page-head p{color:var(--muted);margin:0;font-size:16px}
.section{padding:34px 0}

/* Forms */
.form-card{margin:48px auto;padding:34px}
.form-card h1{font-size:26px;margin:0 0 6px}
.form-card .lead{color:var(--muted);margin:0 0 22px}
.field{margin-bottom:16px}
.field label{display:block;font-weight:600;font-size:14px;margin-bottom:6px}
.field input{width:100%;padding:12px 14px;border:1.5px solid var(--line);border-radius:12px;font-family:inherit;font-size:15px;background:#fff}
.field input:focus{outline:none;border-color:var(--indigo);box-shadow:0 0 0 3px rgba(53,56,205,.12)}
.err{color:var(--danger);font-size:13px;margin-top:5px}
.form-foot{text-align:center;margin-top:16px;color:var(--muted);font-size:14px}

/* Alerts */
.alert{padding:14px 16px;border-radius:12px;margin-bottom:18px;font-size:15px;font-weight:500}
.alert-ok{background:#ECFDF3;color:#15803D;border:1px solid #A7F3D0}
.alert-info{background:var(--indigo-50);color:var(--indigo);border:1px solid #C7D2FE}
.alert-warn{background:#FFFBEB;color:#B45309;border:1px solid #FDE68A}

/* Learn layout */
.learn{display:grid;grid-template-columns:1fr 340px;gap:24px;align-items:start;padding:24px 0}
.player-wrap{background:#000;border-radius:14px;overflow:hidden;aspect-ratio:16/9;position:relative}
.player-wrap iframe,.player-wrap video{width:100%;height:100%;border:0;display:block}
.lesson-side{background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden;max-height:80vh;display:flex;flex-direction:column}
.lesson-side-head{padding:16px;border-bottom:1px solid var(--line);font-weight:800}
.lesson-list{overflow:auto}
.chapter-t{padding:12px 16px;background:#FAFAFE;font-weight:700;font-size:14px;color:var(--muted);border-bottom:1px solid var(--line)}
.lrow{display:flex;align-items:center;gap:10px;padding:12px 16px;border-bottom:1px solid var(--line);font-size:14px;color:var(--ink)}
.lrow:hover{background:var(--indigo-50)}
.lrow.active{background:var(--indigo-50);border-left:3px solid var(--indigo);font-weight:700}
.lrow .ic{width:22px;height:22px;border-radius:50%;display:grid;place-items:center;font-size:12px;flex:none;
  background:#EEF0F4;color:#94a3b8}
.lrow.done .ic{background:#DCFCE7;color:#16a34a}
.lrow.locked{color:#b0b4c3}
.lrow .pv{margin-left:auto;font-size:11px}

/* progress bar */
.pbar{height:8px;background:#EEF0F4;border-radius:999px;overflow:hidden}
.pbar > span{display:block;height:100%;background:linear-gradient(90deg,var(--indigo),var(--coral))}

/* roadmap */
.rm-chapter{margin-bottom:14px}
.rm-chapter h3{margin:0 0 8px;font-size:17px}
.rm-lesson{display:flex;align-items:center;gap:12px;padding:14px 16px;background:#fff;border:1px solid var(--line);
  border-radius:12px;margin-bottom:8px}
.rm-lesson .n{width:28px;height:28px;border-radius:50%;background:var(--indigo-50);color:var(--indigo);
  display:grid;place-items:center;font-weight:700;flex:none}
.rm-lesson.done .n{background:#DCFCE7;color:#16a34a}

/* materials */
.mat{display:flex;align-items:center;gap:12px;padding:12px 14px;border:1px solid var(--line);border-radius:12px;margin-bottom:8px;background:#fff}
.mat .ic{width:36px;height:36px;border-radius:9px;background:#FFECE6;color:var(--coral-600);display:grid;place-items:center;font-weight:800;font-size:13px;flex:none}

/* footer */
.foot{background:#0F1222;color:#B9BECd;padding:30px 0;margin-top:40px}
.foot a{color:#cdd2e0}

.hstack{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.mt-2{margin-top:8px}.mt-4{margin-top:16px}.mt-6{margin-top:24px}.mb-4{margin-bottom:16px}
.text-muted{color:var(--muted)}.text-center{text-align:center}
h1,h2,h3{line-height:1.25}

@media (max-width:900px){
  .grid-3{grid-template-columns:1fr 1fr}
  .learn{grid-template-columns:1fr}
  .nav-links{display:none}
}
@media (max-width:600px){
  .grid-3,.grid-2{grid-template-columns:1fr}
}

/* ===== Footer nhiều cột (đồng bộ trang chủ) ===== */
.foot{background:#0B0E1A;color:#B9BECd;padding:44px 0 26px;margin-top:48px}
.foot .foot-grid{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr 1fr;gap:28px}
.foot h5{color:#fff;font-size:15px;font-weight:700;margin:0 0 12px}
.foot .foot-col a{display:block;color:#AEB4C6;font-size:14px;margin-bottom:9px}
.foot .foot-col a:hover{color:#fff}
.foot .foot-brand p{color:#8891A8;font-size:14px;max-width:34ch;margin:0}
.foot .brand{font-size:20px;font-weight:800;color:#fff;display:flex;align-items:center;gap:10px}
.foot .brand .logo{height:34px;width:auto;object-fit:contain}
.foot .foot-bottom{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;
  border-top:1px solid rgba(255,255,255,.1);margin-top:30px;padding-top:18px;font-size:13px;color:#7B8299}
.foot .foot-bottom{color:#7B8299}
@media (max-width:900px){ .foot .foot-grid{grid-template-columns:1fr 1fr} .foot .foot-brand{grid-column:1/-1} }
@media (max-width:600px){ .foot .foot-grid{grid-template-columns:1fr} }

/* Google login button + separator */
.btn-google{background:#fff;color:#3c4043;border:1.5px solid var(--line);gap:10px}
.btn-google:hover{background:#f7f8fa}
.or-sep{display:flex;align-items:center;gap:12px;color:var(--muted);font-size:13px;margin:18px 0}
.or-sep::before,.or-sep::after{content:"";flex:1;height:1px;background:var(--line)}

/* ===== Mobile tinh chỉnh ===== */
@media (max-width:600px){
  .brand{font-size:17px}
  .brand .logo{height:34px}
  .nav-in{gap:10px;height:58px}
  .page-head h1{font-size:24px}
  .page-head{padding:26px 0 6px}
  .form-card{margin:24px auto;padding:22px}
  .container,.container-sm{padding:0 16px}
  .btn-lg{padding:12px 18px;font-size:15px}
  .learn{padding:14px 0}
}