body{background:#0a0b10;color:#e8eaf2;min-height:100vh;overflow-x:hidden}
:root {
  --bg:   #0d0f1a;
  --bg2:  #131525;
  --bg3:  #1a1d30;
  --ink:  #e8eaf6;
  --ink2: #9095b8;
  --border: rgba(255,255,255,0.07);

  --red:    #c0392b;
  --red-lt: #f5635e;
  --gold:   #c89b3c;
  --gold-lt:#f0c060;
  --teal:   #2ab8a0;
  --rose:   #e86090;

  /* NEW: orange for AI section */
  --ai:     #e07828;
  --ai-lt:  #f5a050;
  --ai-dark:#a05010;

  --radius: 10px;
  --sidebar-w: 220px;

}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--ink);
  font-family: 'Segoe UI', system-ui, sans-serif;
  line-height: 1.65;
  min-height: 100vh;
}

/* -- TOP NAV -- */
.topnav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(13,15,26,0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  display: flex; align-items: center; gap: 16px;
  height: 56px;
}
.nav-logo {
  font-weight: 800; font-size: 1rem; letter-spacing: .03em;
  color: var(--ink); text-decoration: none;
}
.nav-logo span { color: var(--ai-lt); }
.nav-back {
  margin-left: auto;
  color: var(--ink2); font-size: .85rem; text-decoration: none;
  border: 1px solid var(--border); border-radius: 6px;
  padding: 5px 12px;
  transition: all .2s;
}
.nav-back:hover { color: var(--ai-lt); border-color: var(--ai); }

/* -- HERO -- */
.hero {
  background: linear-gradient(135deg, #0a0c18 0%, #1a0e08 50%, #0d0f1a 100%);
  border-bottom: 1px solid var(--border);
  padding: 72px 24px 64px;
  text-align: center;
  position: relative; overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute; inset: 0;
  background: radial-gradient(ellipse 60% 40% at 50% 0%, rgba(224,120,40,0.15), transparent);
  pointer-events: none;
}
.hero-badge {
  display: inline-block;
  background: rgba(224,120,40,0.15);
  border: 1px solid rgba(224,120,40,0.35);
  color: var(--ai-lt);
  font-size: .78rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
  padding: 5px 14px; border-radius: 20px; margin-bottom: 20px;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 900; line-height: 1.1;
  margin-bottom: 16px;
}
.hero h1 span { color: var(--ai-lt); }
.hero p {
  font-size: 1.1rem; color: var(--ink2);
  max-width: 560px; margin: 0 auto 32px;
}
.hero-meta {
  display: flex; justify-content: center; gap: 24px; flex-wrap: wrap;
  font-size: .85rem; color: var(--ink2);
}
.hero-meta span {
  display: flex; align-items: center; gap: 6px;
}
.hero-meta strong { color: var(--ink); }

/* -- SECTION WRAP -- */
.section-wrap {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* -- SECTION HEADER -- */
.course-section { padding: 72px 0; }
.course-section:nth-child(even) { background: var(--bg2); }

.section-label {
  display: flex; align-items: center; gap: 10px;
  font-size: .78rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
  margin-bottom: 12px;
}
.section-label span {
  display: inline-block; width: 20px; height: 3px; border-radius: 2px;
}
.section-heading {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800; margin-bottom: 10px;
}
.section-desc {
  color: var(--ink2); max-width: 640px;
  margin-bottom: 40px;
}

/* -- COURSE GRID -- */
.course-grid {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  gap: 20px;
  align-items: start;
}
@media (max-width: 700px) {
  .course-grid { grid-template-columns: 1fr; }
  .course-sidebar { display: flex; flex-wrap: wrap; gap: 8px; }
}
.course-sidebar { display: flex; flex-direction: column; gap: 6px; }

/* -- STEP BUTTONS -- */
.step-btn {
  width: 100%; text-align: left;
  background: var(--bg3); border: 1px solid var(--border);
  color: var(--ink2); border-radius: var(--radius);
  padding: 10px 14px;
  display: flex; align-items: center; gap: 10px;
  cursor: pointer; transition: all .2s;
  font-size: .88rem;
}
.step-btn:hover { background: rgba(255,255,255,0.05); color: var(--ink); }
.step-btn.active {
  background: rgba(224,120,40,0.12);
  border-color: rgba(224,120,40,0.4);
  color: var(--ink);
}
.step-num {
  min-width: 26px; height: 26px;
  border: 2px solid currentColor;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: .75rem; font-weight: 700;
  color: var(--ai-lt);
}
.step-btn.active .step-num {
  background: var(--ai);
  border-color: var(--ai);
  color: #fff;
}

/* -- STEP PANELS -- */
.course-main { position: relative; }
.step-panel {
  display: none;
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  animation: fadeIn .25s ease;
}
.step-panel.active { display: block; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; } }

.step-tag {
  font-size: .75rem; font-weight: 700; letter-spacing: .1em;
  text-transform: uppercase; margin-bottom: 8px;
  color: var(--ai-lt);
}
.step-title {
  font-size: 1.5rem; font-weight: 800;
  margin-bottom: 20px;
}
.step-body p { color: var(--ink2); margin-bottom: 14px; }
.step-body p strong { color: var(--ink); }

/* -- CODE BLOCKS -- */
.code-block {
  background: #070910;
  border: 1px solid var(--border);
  border-left: 3px solid var(--ai);
  border-radius: 6px;
  padding: 16px 20px;
  font-family: 'Cascadia Code', 'Fira Code', 'Consolas', monospace;
  font-size: .82rem;
  color: #c8d4f0;
  overflow-x: auto;
  margin: 16px 0;
  white-space: pre;
  line-height: 1.7;
}
.code-block .cm  { color: #6a7490; }   /* comment */
.code-block .kw  { color: var(--ai-lt); font-weight: 600; } /* keyword */
.code-block .val { color: #7ec8a8; }   /* value / number */
.code-block .str { color: #f0c060; }   /* string */
.code-block .var { color: #9db4e8; }   /* variable */

/* -- TIP / WARN BOXES -- */
.tip, .warn, .info {
  border-radius: 8px; padding: 14px 18px;
  margin: 16px 0;
  font-size: .9rem;
}
.tip  { background: rgba(42,184,160,0.1); border-left: 3px solid var(--teal);  color: #c0ede6; }
.warn { background: rgba(224,120,40,0.1); border-left: 3px solid var(--ai);    color: #f0c8a0; }
.info { background: rgba(149,155,184,0.1); border-left: 3px solid var(--ink2); color: var(--ink2); }
.tip strong  { color: var(--teal); }
.warn strong { color: var(--ai-lt); }
.info strong { color: var(--ink); }

/* -- TABLE -- */
.data-table {
  width: 100%; border-collapse: collapse;
  font-size: .87rem; margin: 16px 0;
}
.data-table th {
  background: rgba(224,120,40,0.15);
  color: var(--ai-lt);
  text-align: left; padding: 10px 14px;
  border: 1px solid var(--border);
  font-weight: 700; font-size: .78rem; text-transform: uppercase; letter-spacing: .06em;
}
.data-table td {
  padding: 9px 14px;
  border: 1px solid var(--border);
  color: var(--ink2);
}
.data-table td strong { color: var(--ink); }
.data-table tr:hover td { background: rgba(255,255,255,0.03); }

/* -- TRY-IT CHALLENGE -- */
.try-it {
  background: rgba(224,120,40,0.08);
  border: 1px dashed rgba(224,120,40,0.35);
  border-radius: 8px;
  padding: 16px 20px;
  margin: 20px 0;
}
.try-it-label {
  font-size: .75rem; font-weight: 700; letter-spacing: .1em;
  text-transform: uppercase; color: var(--ai-lt);
  margin-bottom: 6px;
}
.try-it p { color: var(--ink2); font-size: .9rem; margin: 0; }

/* -- STEP NAV -- */
.step-nav {
  display: flex; gap: 10px; margin-top: 28px;
  padding-top: 20px; border-top: 1px solid var(--border);
}
.btn-step {
  padding: 10px 20px; border-radius: 6px;
  font-size: .88rem; font-weight: 600;
  cursor: pointer; border: none; transition: all .2s;
}
.btn-step-prev { background: var(--bg); border: 1px solid var(--border); color: var(--ink2); }
.btn-step-prev:hover { color: var(--ink); border-color: rgba(255,255,255,0.2); }
.btn-step-next { background: var(--ai); color: #fff; }
.btn-step-next:hover { background: var(--ai-lt); }
.btn-step:disabled { opacity: .35; cursor: default; pointer-events: none; }

/* -- INTERACTIVE DEMO -- */
.demo-box {
  background: #070910;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px;
  margin: 16px 0;
}
.demo-box label {
  display: block; font-size: .8rem; color: var(--ink2);
  margin-bottom: 6px;
}
.demo-box input[type=range] {
  width: 100%; accent-color: var(--ai);
  margin-bottom: 10px;
}
.demo-output {
  font-family: 'Cascadia Code', monospace;
  font-size: .82rem;
  color: #c8d4f0;
  background: #030408;
  padding: 12px 16px;
  border-radius: 6px;
  border: 1px solid var(--border);
  line-height: 1.8;
}
.demo-output .hi { color: var(--ai-lt); font-weight: 600; }

/* -- PROGRESS BAR -- */
.progress-bar-wrap {
  background: var(--bg3);
  border-radius: 4px; height: 4px;
  margin: 16px 0 28px;
  overflow: hidden;
}
.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--ai-dark), var(--ai-lt));
  border-radius: 4px;
  transition: width .4s ease;
}

/* -- DOWNLOADS -- */
.dl-section {
  background: var(--bg2);
  border-top: 1px solid var(--border);
  padding: 72px 0;
}
.dl-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 32px;
}
.dl-card {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  display: flex; flex-direction: column; gap: 10px;
  transition: border-color .2s;
}
.dl-card:hover { border-color: rgba(224,120,40,0.4); }
.dl-card-icon { font-size: 1.6rem; }
.dl-card-title { font-weight: 700; }
.dl-card-desc { font-size: .85rem; color: var(--ink2); flex: 1; }
.dl-btn {
  display: inline-block;
  background: var(--ai);
  color: #fff; font-weight: 600; font-size: .85rem;
  padding: 9px 18px; border-radius: 6px;
  text-decoration: none; text-align: center;
  transition: background .2s;
  cursor: pointer; border: none;
}
.dl-btn:hover { background: var(--ai-lt); }

/* -- FOOTER -- */
footer {
  background: #070910;
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  text-align: center;
  font-size: .82rem; color: var(--ink2);
}
footer a { color: var(--ai-lt); text-decoration: none; }

/* -- REVEAL ANIMATION -- */
/* -- MOBILE RESPONSIVE PATCH ---------------------------- */
@media(max-width:860px){
  .course-grid{grid-template-columns:1fr;}
  .course-sidebar{display:flex;flex-wrap:wrap;gap:8px;flex-direction:row;}
  .step-btn{flex:1 1 140px;font-size:.8rem;padding:8px 10px;}
}
@media(max-width:480px){
  .step-btn{flex:1 1 100%;font-size:.78rem;}
  .hero{padding:48px 16px 36px;}
  .hero p{font-size:.95rem;}
}
/* ------------------------------------------------------- */
.reveal{opacity:1!important;transform:none!important}