/* ============================================================
   Uncodemy Topic Pages — Design System
   Primary: #FF5421 | Heading: Poppins | Body: Inter
   ============================================================ */

:root {
  --primary: #FF5421;
  --primary-dark: #D9430F;
  --primary-light: #FFF1EC;
  --primary-lighter: #FFF8F5;

  --text: #1F2430;
  --text-muted: #6B7280;
  --text-faint: #9CA3AF;

  --bg: #FAFAFB;
  --card-bg: #FFFFFF;
  --border: #ECEEF2;

  --radius-lg: 18px;
  --radius-md: 14px;
  --radius-sm: 9px;

  --shadow-sm: 0 2px 8px rgba(31, 36, 48, 0.05);
  --shadow-md: 0 8px 28px rgba(31, 36, 48, 0.08);
  --shadow-lg: 0 16px 40px rgba(31, 36, 48, 0.12);

  --font-heading: 'Poppins', sans-serif;
  --font-body: 'Inter', sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  animation: pageFadeIn 0.5s ease both;
}

@keyframes pageFadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; }
}

h1, h2, h3, h4 { font-family: var(--font-heading); color: var(--text); margin: 0 0 12px; line-height: 1.3; }
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; }

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* ---------- Topbar ---------- */
.topbar {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
}
.topbar-inner {
  max-width: 1480px;
  margin: 0 auto;
  padding: 14px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo img { height: 34px; }
.back-to-course-btn {
  border: 1.5px solid var(--primary);
  color: var(--primary);
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 13.5px;
  padding: 9px 18px;
  border-radius: 999px;
  transition: background 0.2s ease, color 0.2s ease, transform 0.15s ease;
}
.back-to-course-btn:hover {
  background: var(--primary);
  color: #fff;
  transform: translateY(-1px);
}

/* ---------- Breadcrumb ---------- */
.breadcrumb {
  max-width: 1480px;
  margin: 0 auto;
  padding: 16px 28px 0;
  font-size: 13.5px;
  color: var(--text-muted);
}
.breadcrumb a { color: var(--primary); font-weight: 600; }
.breadcrumb .sep { margin: 0 6px; color: var(--text-faint); }

/* ---------- Page Layout (3 columns, widened) ---------- */
.page-container {
  max-width: 1480px;
  margin: 0 auto;
  padding: 18px 20px 60px;
  display: grid;
  grid-template-columns: 268px minmax(0, 1fr) 300px;
  gap: 24px;
  align-items: start;
}

/* ---------- Left Sidebar ---------- */
.left-sidebar {
  position: sticky;
  top: 78px;
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 18px 14px;
  max-height: calc(100vh - 96px);
  overflow-y: auto;
}
.left-sidebar h4 {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-faint);
  padding: 4px 10px 10px;
}
.mobile-sidebar-toggle { display: none; }

.topic-link {
  display: block;
  padding: 10px 12px;
  margin-bottom: 3px;
  border-radius: var(--radius-sm);
  font-size: 13.6px;
  font-weight: 500;
  color: var(--text);
  line-height: 1.4;
  transition: background 0.15s ease, color 0.15s ease, padding-left 0.15s ease;
}
.topic-link:hover {
  background: var(--primary-lighter);
  color: var(--primary-dark);
  padding-left: 16px;
}
.topic-link.active {
  background: var(--primary);
  color: #fff;
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

/* scrollbar polish */
.left-sidebar::-webkit-scrollbar { width: 6px; }
.left-sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 10px; }

/* ---------- Main Content ---------- */
.main-content { min-width: 0; }

.content-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 34px 38px;
}

.content-card h1 {
  font-size: 30px;
  font-weight: 700;
}

.content-card .subtitle {
  color: var(--text-muted);
  font-size: 14.5px;
  margin-bottom: 22px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--border);
}

.content-card h2 {
  font-size: 20px;
  margin-top: 30px;
  padding-left: 12px;
  border-left: 4px solid var(--primary);
}

.content-card h3 {
  font-size: 16.5px;
  margin-top: 20px;
  color: var(--primary-dark);
}

.content-card p, .content-card li {
  font-size: 15.2px;
  line-height: 1.75;
  color: #3A3F4B;
}

.content-card ul, .content-card ol {
  padding-left: 22px;
  margin: 0 0 16px;
}

.content-card code {
  background: var(--primary-light);
  color: var(--primary-dark);
  padding: 2px 7px;
  border-radius: 5px;
  font-size: 13.6px;
  font-family: 'SFMono-Regular', Consolas, monospace;
}

.content-card pre {
  background: #1F2430;
  color: #F1F1F4;
  padding: 18px 20px;
  border-radius: var(--radius-md);
  overflow-x: auto;
  font-size: 13.4px;
  margin: 0 0 18px;
  line-height: 1.6;
}
.content-card pre code { background: none; color: inherit; padding: 0; }

.highlight-box {
  background: var(--primary-light);
  border-left: 4px solid var(--primary);
  border-radius: var(--radius-sm);
  padding: 15px 18px;
  margin: 22px 0;
  font-size: 14.4px;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: 4px 0 20px;
  font-size: 13.8px;
}
.comparison-table th, .comparison-table td {
  border: 1px solid var(--border);
  padding: 10px 12px;
  text-align: left;
}
.comparison-table th {
  background: var(--primary-light);
  color: var(--primary-dark);
  font-family: var(--font-heading);
  font-weight: 600;
}
.comparison-table tr:nth-child(even) td { background: #FAFAFC; }

/* ---------- Prev / Next Nav ---------- */
.prev-next-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 22px;
}
.prev-link, .next-link {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 13px 16px;
  display: flex;
  flex-direction: column;
  gap: 3px;
  transition: border-color 0.2s ease, transform 0.15s ease, box-shadow 0.2s ease;
}
.next-link { text-align: right; }
.prev-link:hover, .next-link:hover {
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}
.prev-link .label, .next-link .label {
  font-size: 11.5px;
  color: var(--primary);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.prev-link .title, .next-link .title {
  font-size: 13.6px;
  font-weight: 600;
  color: var(--text);
}
.disabled { opacity: 0.4; pointer-events: none; }

/* ---------- CTA Box ---------- */
.cta-box {
  margin-top: 26px;
  background: linear-gradient(135deg, var(--primary) 0%, #FF7A4D 100%);
  border-radius: var(--radius-lg);
  padding: 30px 34px;
  color: #fff;
  box-shadow: var(--shadow-md);
}
.cta-box h3 { color: #fff; font-size: 20px; }
.cta-box p { color: rgba(255,255,255,0.92); font-size: 14.5px; margin-bottom: 18px; }
.cta-btn {
  display: inline-block;
  background: #fff;
  color: var(--primary-dark);
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 14px;
  padding: 12px 24px;
  border-radius: 999px;
  transition: transform 0.15s ease, box-shadow 0.2s ease;
}
.cta-btn:hover { transform: translateY(-2px) scale(1.02); box-shadow: 0 10px 24px rgba(0,0,0,0.15); }

/* ---------- Right Sidebar ---------- */
.right-sidebar {
  position: sticky;
  top: 78px;
  display: flex;
  flex-direction: column;
  gap: 18px;
  max-height: calc(100vh - 96px);
}

.batch-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 22px;
  animation: cardIn 0.5s ease both 0.1s;
}

@keyframes cardIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.badge {
  display: inline-block;
  background: var(--primary-light);
  color: var(--primary-dark);
  font-size: 12px;
  font-weight: 700;
  padding: 6px 12px;
  border-radius: 999px;
  margin-bottom: 12px;
  animation: floatBadge 3s ease-in-out infinite;
}

@keyframes floatBadge {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-3px); }
}

.batch-card h4 {
  font-size: 18px;
  margin-bottom: 4px;
}
.course-name {
  color: var(--primary);
  font-weight: 600;
  font-size: 13.5px;
  margin-bottom: 10px;
}
.batch-meta {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 4px;
}
.batch-meta b { color: var(--text); }

.countdown-wrap {
  margin: 16px 0;
  background: var(--primary-lighter);
  border-radius: var(--radius-md);
  padding: 14px;
}
.countdown-label {
  font-size: 11.5px;
  color: var(--primary-dark);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 10px;
  text-align: center;
}
.countdown-timer {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 6px;
}
.countdown-timer .unit {
  background: #fff;
  border-radius: var(--radius-sm);
  padding: 8px 2px;
  text-align: center;
  box-shadow: var(--shadow-sm);
}
.countdown-timer .num {
  font-family: var(--font-heading);
  font-size: 17px;
  font-weight: 700;
  color: var(--primary);
}
.countdown-timer .lbl {
  font-size: 9.5px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.feature-list {
  list-style: none;
  padding: 0;
  margin: 0 0 16px;
}
.feature-list li {
  font-size: 13.4px;
  color: #3A3F4B;
  padding: 6px 0 6px 24px;
  position: relative;
}
.feature-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--primary);
  font-weight: 700;
}

.limited-seats {
  text-align: center;
  font-size: 12.5px;
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 10px;
}

.landing-cta-btn {
  width: 100%;
  background: var(--primary);
  color: #fff;
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 14.5px;
  border: none;
  padding: 13px 18px;
  border-radius: var(--radius-md);
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s ease, box-shadow 0.2s ease, background 0.2s ease;
}
.landing-cta-btn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px) scale(1.015);
  box-shadow: var(--shadow-md);
}

.help-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 20px 22px;
  animation: cardIn 0.5s ease both 0.2s;
}
.help-card h4 { font-size: 15.5px; margin-bottom: 12px; }
.help-row {
  font-size: 13.6px;
  color: #3A3F4B;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 0;
  border-top: 1px solid var(--border);
}
.help-row:first-of-type { border-top: none; }
.help-row a { color: var(--primary-dark); font-weight: 600; transition: color 0.15s ease; }
.help-row a:hover { color: var(--primary); }

/* ---------- Footer ---------- */
footer {
  border-top: 1px solid var(--border);
  background: var(--card-bg);
  margin-top: 20px;
}
.footer-inner {
  max-width: 1480px;
  margin: 0 auto;
  padding: 20px 28px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: var(--text-muted);
}
.footer-inner a { color: var(--primary); font-weight: 600; }

/* ============================================================
   Responsive
   ============================================================ */

/* Tablet: sidebars drop below content */
@media (max-width: 1024px) {
  .page-container {
    grid-template-columns: 1fr;
  }
  .left-sidebar {
    position: relative;
    top: 0;
    max-height: none;
    order: 2;
  }
  .main-content { order: 1; }
  .right-sidebar {
    position: relative;
    top: 0;
    max-height: none;
    order: 3;
    flex-direction: row;
    flex-wrap: wrap;
  }
  .right-sidebar .batch-card,
  .right-sidebar .help-card {
    flex: 1 1 280px;
  }
  .mobile-sidebar-toggle {
    display: block;
    width: 100%;
    background: var(--primary-light);
    color: var(--primary-dark);
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 14px;
    border: none;
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    margin-bottom: 10px;
    cursor: pointer;
  }
  .left-sidebar .topic-links { display: none; }
  .left-sidebar.open .topic-links { display: block; }
}

/* Mobile: full-width single column */
@media (max-width: 640px) {
  .topbar-inner { padding: 12px 16px; }
  .logo img { height: 28px; }
  .back-to-course-btn { padding: 7px 13px; font-size: 12.5px; }
  .breadcrumb { padding: 12px 16px 0; font-size: 12.5px; }
  .page-container { padding: 14px 12px 40px; gap: 16px; }
  .content-card { padding: 22px 18px; }
  .content-card h1 { font-size: 23px; }
  .prev-next-nav { grid-template-columns: 1fr; }
  .next-link { text-align: left; }
  .cta-box { padding: 22px 20px; }
  .right-sidebar { flex-direction: column; }
  .right-sidebar .batch-card, .right-sidebar .help-card { flex: 1 1 auto; }
  .footer-inner { flex-direction: column; gap: 6px; text-align: center; }
}