:root {
  --bg-main: #090d16;
  --bg-card: #111827;
  --bg-card-hover: #1e293b;
  --border: #1f2937;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --accent-cyan: #38bdf8;
  --accent-gold: #f59e0b;
  --accent-green: #10b981;
  --accent-red: #ef4444;
}

* { box-sizing: border-box; margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
body { background: var(--bg-main); color: var(--text-main); min-height: 100vh; display: flex; flex-direction: column; }

/* Navbar */
.navbar {
  background: rgba(17, 24, 39, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  padding: 16px 32px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 100;
}
.brand {
  font-size: 20px;
  font-weight: 900;
  color: #fff;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 8px;
}
.brand span { color: var(--accent-gold); }
.nav-links { display: flex; gap: 20px; align-items: center; }
.nav-link { color: var(--text-muted); text-decoration: none; font-size: 14px; font-weight: 600; transition: color 0.2s; }
.nav-link:hover { color: #fff; }
.nav-badge { background: rgba(56, 189, 248, 0.15); color: var(--accent-cyan); padding: 4px 12px; border-radius: 20px; font-size: 12px; font-weight: 700; }

/* Container */
.container { max-width: 1200px; margin: 0 auto; padding: 30px 20px; width: 100%; }

/* Hero */
.hero { text-align: center; padding: 40px 0 30px; }
.hero-tag {
  display: inline-block;
  background: rgba(245, 158, 11, 0.15);
  color: var(--accent-gold);
  border: 1px solid rgba(245, 158, 11, 0.3);
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  margin-bottom: 14px;
  letter-spacing: 0.5px;
}
.hero h1 { font-size: 38px; font-weight: 900; margin-bottom: 12px; color: #fff; }
.hero p { font-size: 16px; color: var(--text-muted); max-width: 750px; margin: 0 auto 24px; line-height: 1.6; }

/* Modules & Cards */
.module-box {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  margin-bottom: 24px;
}
.module-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 12px;
}
.lesson-card {
  background: #0f172a;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 20px;
  margin-bottom: 12px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  transition: all 0.2s;
}
.lesson-card:hover { border-color: var(--accent-cyan); transform: translateX(4px); }
.lesson-info h3 { font-size: 16px; font-weight: 700; color: #fff; margin-bottom: 4px; }
.lesson-info p { font-size: 13.5px; color: var(--text-muted); line-height: 1.4; }
.btn-action {
  background: var(--accent-cyan);
  color: #090d16;
  padding: 9px 18px;
  border-radius: 8px;
  text-decoration: none;
  font-size: 13.5px;
  font-weight: 800;
  white-space: nowrap;
  transition: opacity 0.2s;
}
.btn-action:hover { opacity: 0.9; }

/* Video Embed */
.video-container {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  border-radius: 12px;
  background: #000;
  margin-bottom: 24px;
  border: 1px solid var(--border);
}
.video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* Test Section */
.test-section {
  background: #0f172a;
  border: 2px dashed rgba(245, 158, 11, 0.4);
  border-radius: 14px;
  padding: 24px;
  margin-top: 30px;
}
.opt-label {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  padding: 12px 16px;
  border-radius: 8px;
  margin-bottom: 10px;
  cursor: pointer;
  font-size: 14.5px;
  line-height: 1.5;
  transition: all 0.2s;
}
.opt-label:hover { border-color: var(--accent-gold); }
.btn-test {
  background: var(--accent-gold);
  color: #090d16;
  border: none;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 800;
  cursor: pointer;
  margin-top: 14px;
}