/* ── Variables ─────────────────────────────────────────────────────────────── */
:root {
  --bg:       #0d1117;
  --bg2:      #161b22;
  --bg3:      #1c2230;
  --surface:  #161b22;
  --surface2: #1c2230;
  --border:   #30363d;
  --text:     #e6edf3;
  --text2:    #8b949e;
  --text3:    #6e7681;
  --accent:   #39d0b8;
  --accent2:  #2bb8a1;
  --warn:     #f0a040;
  --danger:   #e05656;
  --success:  #3fb950;
  --mono:     'IBM Plex Mono', monospace;
  --sans:     'IBM Plex Sans', sans-serif;
  --radius:   6px;
  --header-h: 53px;
}

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

html { font-size: 16px; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent2); text-decoration: underline; }

h1, h2, h3, h4 { line-height: 1.3; font-weight: 600; }
h1 { font-size: 2rem; margin-bottom: .75rem; }
h2 { font-size: 1.4rem; margin: 1.5rem 0 .5rem; }
h3 { font-size: 1.1rem; margin: 1rem 0 .25rem; }

p { margin-bottom: .75rem; }

code {
  font-family: var(--mono);
  font-size: .875em;
  background: var(--bg3);
  padding: .15em .35em;
  border-radius: 3px;
  color: var(--accent);
}

pre {
  font-family: var(--mono);
  font-size: .875rem;
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  overflow-x: auto;
  line-height: 1.5;
}

pre code {
  background: none;
  padding: 0;
  color: var(--text);
}

table { border-collapse: collapse; width: 100%; margin: 1rem 0; }
th, td { border: 1px solid var(--border); padding: .5rem .75rem; text-align: left; }
th { background: var(--bg3); color: var(--text2); font-weight: 500; font-size: .875rem; }

input, textarea, select {
  display: block;
  width: 100%;
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-family: var(--sans);
  font-size: .9375rem;
  padding: .5rem .75rem;
  margin-top: .3rem;
  outline: none;
  transition: border-color .15s;
}
input:focus, textarea:focus, select:focus { border-color: var(--accent); }
textarea { resize: vertical; min-height: 80px; }
textarea.mono { font-family: var(--mono); font-size: .875rem; }

label { display: block; margin-bottom: 1rem; font-size: .9375rem; color: var(--text2); }
label > input, label > textarea, label > select { color: var(--text); }

hr { border: none; border-top: 1px solid var(--border); margin: 2rem 0; }

/* ── Utilities ─────────────────────────────────────────────────────────────── */
.container { max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; }
.text2 { color: var(--text2); }
.text3 { color: var(--text3); font-size: .875rem; }

/* ── Buttons ───────────────────────────────────────────────────────────────── */
.btn {
  display: inline-block;
  padding: .5rem 1rem;
  border-radius: var(--radius);
  font-family: var(--sans);
  font-size: .9375rem;
  font-weight: 500;
  cursor: pointer;
  border: 1px solid var(--border);
  background: var(--bg3);
  color: var(--text);
  text-decoration: none;
  transition: background .15s, border-color .15s, color .15s;
  white-space: nowrap;
}
.btn:hover { background: var(--bg2); border-color: var(--text3); color: var(--text); text-decoration: none; }

.btn-primary { background: var(--accent); border-color: var(--accent); color: #0d1117; }
.btn-primary:hover { background: var(--accent2); border-color: var(--accent2); color: #0d1117; }

.btn-secondary { background: var(--bg3); border-color: var(--border); color: var(--text2); }
.btn-secondary:hover { border-color: var(--text3); color: var(--text); }

.btn-danger { background: transparent; border-color: var(--danger); color: var(--danger); }
.btn-danger:hover { background: var(--danger); color: #fff; }

.btn-sm { font-size: .8125rem; padding: .3rem .65rem; }

/* ── Flash messages ────────────────────────────────────────────────────────── */
.flash {
  padding: .75rem 1.25rem;
  border-radius: var(--radius);
  margin-bottom: 1rem;
  font-size: .9375rem;
}
.flash-info    { background: #1a2a3a; border: 1px solid #2a5080; color: #7ab8f5; }
.flash-success { background: #112218; border: 1px solid #2d6a3f; color: var(--success); }
.flash-danger  { background: #2a1212; border: 1px solid #6a2d2d; color: var(--danger); }
.flash-warn    { background: #2a2010; border: 1px solid #6a4a10; color: var(--warn); }

/* ── Site header ───────────────────────────────────────────────────────────── */
.site-header {
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  padding: .75rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.brand {
  font-family: var(--mono);
  font-size: 1.125rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: -.02em;
}
.brand:hover { color: var(--accent2); text-decoration: none; }
.site-header nav { display: flex; align-items: center; gap: 1.25rem; }
.site-header nav a { color: var(--text2); font-size: .9375rem; }
.site-header nav a:hover { color: var(--text); text-decoration: none; }
.site-header nav a.btn-primary { color: #000; }
.site-header nav a.btn-primary:hover { color: #000; }

/* ── Hero ──────────────────────────────────────────────────────────────────── */
.hero {
  padding: 4rem 0 2rem;
  text-align: center;
}
.hero h1 {
  font-family: var(--mono);
  font-size: 2.5rem;
  color: var(--accent);
  margin-bottom: .75rem;
}
.tagline { font-size: 1.125rem; color: var(--text2); max-width: 600px; margin: 0 auto; }

/* ── Course grid ───────────────────────────────────────────────────────────── */
.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
  padding: 2rem 0 4rem;
}
.course-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: .75rem;
  transition: border-color .15s;
}
.course-card:hover { border-color: var(--accent); }
.course-card h2 { font-size: 1.1rem; margin: 0; }
.course-card h2 a { color: var(--text); }
.course-card h2 a:hover { color: var(--accent); text-decoration: none; }
.course-card-footer { display: flex; align-items: center; justify-content: space-between; margin-top: auto; }
.prices { display: flex; flex-direction: column; gap: .15rem; }
.price { font-family: var(--mono); font-size: .875rem; color: var(--accent); }
.price-sub { font-family: var(--mono); font-size: .875rem; color: var(--text2); }

/* ── Course hero ───────────────────────────────────────────────────────────── */
.course-hero {
  padding: 3rem 0 2rem;
  max-width: 720px;
}
.pricing-box {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 1.5rem;
  align-items: center;
}
.access-badge { color: var(--success); font-weight: 500; margin-top: 1rem; }

/* ── Curriculum ────────────────────────────────────────────────────────────── */
.curriculum { padding: 2rem 0 4rem; }
.curriculum-section { margin-bottom: 1.25rem; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.curriculum-section h3 {
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
  padding: .7rem 1rem;
  font-size: .8125rem;
  text-transform: uppercase;
  letter-spacing: .07em;
  color: var(--accent);
  margin: 0;
  font-weight: 600;
}
.curriculum-section ul { list-style: none; }
.curriculum-section li { border-bottom: 1px solid var(--border); }
.curriculum-section li:last-child { border-bottom: none; }
.curriculum-section li a {
  display: flex;
  align-items: center;
  gap: .6rem;
  padding: .6rem 1rem .6rem 1.5rem;
  color: var(--text2);
  font-size: .9375rem;
}
.curriculum-section li a::before {
  content: '';
  display: inline-block;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--border);
  flex-shrink: 0;
  transition: background .15s;
}
.curriculum-section li a:hover { color: var(--text); text-decoration: none; background: var(--bg3); }
.curriculum-section li a:hover::before { background: var(--accent); }

/* ── Breadcrumb ────────────────────────────────────────────────────────────── */
.breadcrumb { font-size: .8125rem; color: var(--text3); margin-bottom: 1.5rem; }
.breadcrumb a { color: var(--text3); }
.breadcrumb a:hover { color: var(--text2); }

/* ── Lesson layout ─────────────────────────────────────────────────────────── */
.lesson-wrap {
  display: grid;
  grid-template-columns: 260px 1fr;
  min-height: calc(100vh - var(--header-h));
}

.lesson-sidebar {
  background: var(--bg2);
  border-right: 1px solid var(--border);
  padding: 1.5rem 0;
  overflow-y: auto;
  position: sticky;
  top: var(--header-h);
  max-height: calc(100vh - var(--header-h));
}
.sidebar-course { padding: .5rem 1.25rem 1rem; }
.sidebar-course-link { font-size: .8125rem; color: var(--text3); }
.sidebar-course-link:hover { color: var(--accent); }
.sidebar-section { margin-bottom: .5rem; }
.sidebar-section-title {
  padding: .55rem 1.25rem .4rem;
  font-size: .7rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--accent);
  font-weight: 700;
  border-top: 1px solid var(--border);
  margin-top: .25rem;
}
.sidebar-section:first-child .sidebar-section-title { border-top: none; margin-top: 0; }
.lesson-sidebar ul { list-style: none; }
.lesson-sidebar li a {
  display: flex;
  align-items: center;
  gap: .5rem;
  padding: .38rem 1.25rem .38rem 1.5rem;
  font-size: .8375rem;
  color: var(--text2);
  border-left: 2px solid transparent;
  transition: background .1s, color .1s, border-color .1s;
}
.lesson-sidebar li a::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--border);
  flex-shrink: 0;
  transition: background .15s;
}
.lesson-sidebar li a:hover { background: var(--bg3); color: var(--text); text-decoration: none; }
.lesson-sidebar li a:hover::before { background: var(--text3); }
.lesson-sidebar li.active a {
  color: var(--accent);
  border-left-color: var(--accent);
  background: rgba(57,208,184,.07);
}
.lesson-sidebar li.active a::before { background: var(--accent); }

.lesson-content { padding: 2rem 3rem 4rem; max-width: 820px; }

/* ── Block heading ─────────────────────────────────────────────────────────── */
.block-heading {
  display: flex;
  align-items: center;
  gap: .75rem;
  font-size: .8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--accent);
  margin: 2.5rem 0 1rem;
}
.block-heading::before {
  content: '';
  display: block;
  width: 3px;
  height: 1.1em;
  background: var(--accent);
  border-radius: 2px;
}

/* ── Setup block ───────────────────────────────────────────────────────────── */
.setup-block {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 2rem;
  overflow: hidden;
}
.setup-block-header {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .75rem 1rem;
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.block-label {
  font-family: var(--mono);
  font-size: .75rem;
  font-weight: 500;
  background: rgba(57,208,184,.15);
  color: var(--accent);
  padding: .15em .5em;
  border-radius: 3px;
}
.setup-actions { display: flex; gap: .5rem; margin-left: auto; }
.setup-block pre { border: none; border-radius: 0; margin: 0; }
.setup-instructions { padding: 1rem 1.25rem; border-top: 1px solid var(--border); }

/* ── Theory block ──────────────────────────────────────────────────────────── */
.theory-block { margin-bottom: 2rem; }

/* ── Markdown content ──────────────────────────────────────────────────────── */
.md-content { line-height: 1.75; }
.md-content h1 { font-size: 1.6rem; margin: 2rem 0 .75rem; }
.md-content h2 { font-size: 1.25rem; margin: 1.75rem 0 .6rem; color: var(--text); }
.md-content h3 { font-size: 1rem; margin: 1.25rem 0 .4rem; color: var(--text2); }
.md-content p { margin-bottom: .875rem; }
.md-content ul, .md-content ol { padding-left: 1.5rem; margin-bottom: .875rem; }
.md-content li { margin-bottom: .25rem; }
.md-content blockquote {
  border-left: 3px solid var(--accent);
  padding: .5rem 1rem;
  background: var(--bg3);
  margin: 1rem 0;
  color: var(--text2);
}
.md-content table { font-size: .875rem; }
/* ── Code block with header bar ─────────────────────────────────────────────── */
.md-content .pre-wrap {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 1rem 0;
}
.md-content .pre-wrap pre {
  border: none;
  border-radius: 0;
  margin: 0;
}
.code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: .35rem .75rem;
  background: #0d1117;
  border-bottom: 1px solid var(--border);
  min-height: 36px;
}
.code-lang {
  font-family: var(--mono);
  font-size: .7rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text3);
}
.code-copy-btn {
  display: inline-flex;
  align-items: center;
  gap: .35rem;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text3);
  font-family: var(--mono);
  font-size: .7rem;
  padding: .25rem .6rem;
  cursor: pointer;
  transition: color .15s, border-color .15s, background .15s;
  /* Large enough touch target */
  min-height: 28px;
  min-width: 64px;
  justify-content: center;
  width: auto;
  margin: 0;
}
.code-copy-btn:hover { color: var(--text); border-color: var(--text3); background: var(--bg3); }
.code-copy-btn.copied { color: var(--success); border-color: var(--success); }
.code-copy-btn svg { flex-shrink: 0; }

/* ── Q&A ────────────────────────────────────────────────────────────────────── */
.qa-block {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 1rem;
  overflow: hidden;
}
.qa-label {
  display: inline-block;
  font-family: var(--mono);
  font-size: .75rem;
  font-weight: 600;
  background: rgba(240,160,64,.15);
  color: var(--warn);
  padding: .1em .45em;
  border-radius: 3px;
  margin-right: .5rem;
  vertical-align: middle;
}
.qa-question {
  padding: .875rem 1.25rem;
  cursor: pointer;
  user-select: none;
  background: var(--bg2);
  transition: background .1s;
}
.qa-question:hover { background: var(--bg3); }
.qa-question.open { border-bottom: 1px solid var(--border); }
.qa-question p { margin: 0; display: inline; }
.qa-answer { display: none; padding: 1.25rem; background: var(--bg); }
.qa-answer.open { display: block; }
.qa-locked { text-align: center; padding: 1.5rem; }
.qa-locked p { color: var(--text2); margin-bottom: 1rem; }

/* ── Lesson navigation ─────────────────────────────────────────────────────── */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

/* ── Auth forms ────────────────────────────────────────────────────────────── */
.auth-wrap { display: flex; justify-content: center; padding: 4rem 0; }
.auth-box {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2.5rem;
  width: 100%;
  max-width: 420px;
}
.auth-box h1 { font-size: 1.5rem; margin-bottom: 1.5rem; }
.auth-box .btn { width: 100%; text-align: center; margin-top: .5rem; }
.auth-switch { text-align: center; color: var(--text3); font-size: .875rem; margin-top: 1.25rem; }

/* ── Error page ────────────────────────────────────────────────────────────── */
.error-page { text-align: center; padding: 6rem 0; }
.error-page h1 { font-size: 5rem; font-family: var(--mono); color: var(--text3); }
.error-page p { color: var(--text2); margin-bottom: 1.5rem; }

/* ── Admin layout ──────────────────────────────────────────────────────────── */
.admin-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  min-height: calc(100vh - var(--header-h));
}

.admin-nav {
  background: var(--bg2);
  border-right: 1px solid var(--border);
  padding: 1.5rem 0;
  position: sticky;
  top: var(--header-h);
  max-height: calc(100vh - var(--header-h));
  overflow-y: auto;
}
.admin-brand { padding: .5rem 1.25rem 1rem; }
.admin-brand a { font-family: var(--mono); font-size: .875rem; color: var(--text3); }
.admin-nav a {
  display: block;
  padding: .55rem 1.25rem;
  font-size: .9375rem;
  color: var(--text2);
  border-left: 2px solid transparent;
  transition: background .1s, color .1s;
}
.admin-nav a:hover { background: var(--bg3); color: var(--text); text-decoration: none; }
.admin-nav a.active { color: var(--accent); border-left-color: var(--accent); background: rgba(57,208,184,.07); }

.admin-content { padding: 2rem 2.5rem 4rem; max-width: 1000px; }

.admin-page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
}
.admin-page-header h1, .admin-page-header h2 { margin: 0; }

/* ── Admin table ───────────────────────────────────────────────────────────── */
.admin-table { font-size: .875rem; }
.admin-table th { font-size: .8125rem; }
.admin-table td { vertical-align: top; }

/* ── Stripe mode toggle ─────────────────────────────────────────────────────── */
.stripe-mode-toggle { display:flex; align-items:center; gap:.75rem; }
.stripe-mode-badge { font-size:.8rem; font-weight:700; padding:.3rem .8rem; border-radius:999px; letter-spacing:.04em; }
.stripe-mode-live { background:rgba(34,197,94,.15); color:#22c55e; border:1px solid rgba(34,197,94,.3); }
.stripe-mode-test { background:rgba(234,179,8,.15); color:#eab308; border:1px solid rgba(234,179,8,.3); }

/* ── Admin stat grid ───────────────────────────────────────────────────────── */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 1rem;
  margin-bottom: 2.5rem;
}
.stat-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: .25rem;
}
.stat-n { font-family: var(--mono); font-size: 2rem; font-weight: 500; color: var(--accent); }
.stat-card span:last-child { font-size: .8125rem; color: var(--text3); }
.stat-card-highlight { border-color: var(--accent); }
.stat-card-highlight .stat-n { color: #4ade80; }

/* ── Admin block card ──────────────────────────────────────────────────────── */
.admin-block-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

/* ── Admin section/lesson list ─────────────────────────────────────────────── */
.admin-section-block {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 1rem;
  overflow: hidden;
}
.admin-section-header {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .75rem 1rem;
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.admin-lesson-list { list-style: none; }
.admin-lesson-list li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: .6rem 1rem;
  border-bottom: 1px solid var(--border);
  gap: 1rem;
}
.admin-lesson-list li:last-child { border-bottom: none; }

/* ── Badges ────────────────────────────────────────────────────────────────── */
.badge-green {
  display: inline-block;
  font-size: .75rem;
  padding: .15em .5em;
  border-radius: 3px;
  background: rgba(63,185,80,.15);
  color: var(--success);
}
.badge-gray {
  display: inline-block;
  font-size: .75rem;
  padding: .15em .5em;
  border-radius: 3px;
  background: var(--bg3);
  color: var(--text3);
}

/* ── Form helpers ──────────────────────────────────────────────────────────── */
.form-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}
.form-row label { flex: 1; min-width: 180px; }
.form-actions { display: flex; gap: .75rem; align-items: center; margin-top: .5rem; }
.label-check { display: flex; align-items: center; gap: .5rem; margin-top: 1.75rem; }
.label-check input { width: auto; margin: 0; }

.warn-text { color: var(--warn); font-size: .8125rem; display: block; margin-top: .25rem; }

/* ══════════════════════════════════════════════════════════════════════════════
   RESPONSIVE — mobile first
   ══════════════════════════════════════════════════════════════════════════════ */

/* Desktop: sidebar always open, toggle hidden */
@media (min-width: 769px) {
  .sidebar-toggle { display: none; }
  .sidebar-body   { display: block !important; }
}

/* ── 768px: tablet ─────────────────────────────────────────────────────────── */
@media (max-width: 768px) {

  /* Nav */
  .site-header .container { gap: .5rem; }
  .site-header nav { gap: .75rem; overflow-x: auto; -webkit-overflow-scrolling: touch; padding-bottom: 2px; }
  .site-header nav a { font-size: .875rem; white-space: nowrap; }

  /* Hero */
  .hero-section { padding: 3.5rem 1.25rem 3rem; }
  .hero-sub { font-size: 1rem; }
  .hero-trust { gap: .75rem; font-size: .75rem; }
  .btn-lg { padding: .65rem 1.25rem; font-size: .9375rem; }

  /* Course grid */
  .course-grid { grid-template-columns: 1fr; padding: 1.5rem 0 3rem; gap: 1rem; }

  /* Course detail */
  .course-hero { padding: 2rem 0 1.5rem; }
  .pricing-box { flex-direction: column; align-items: stretch; }
  .pricing-box form { width: 100%; }
  .pricing-box .btn { width: 100%; text-align: center; }

  /* Lesson layout — sidebar stacks above content */
  .lesson-wrap { grid-template-columns: 1fr; grid-template-rows: auto 1fr; }
  .lesson-sidebar {
    position: static;
    max-height: none;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 0;
  }
  /* Sidebar toggle button */
  .sidebar-toggle {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: .75rem 1.25rem;
    font-size: .875rem;
    font-weight: 500;
    color: var(--text2);
    cursor: pointer;
    background: var(--bg2);
    user-select: none;
  }
  .sidebar-toggle::after { content: '▾'; font-size: .75rem; transition: transform .2s; }
  .sidebar-toggle.open::after { transform: rotate(180deg); }
  .sidebar-body { display: none; }
  .sidebar-body.open { display: block; border-top: 1px solid var(--border); }

  .lesson-content { padding: 1.5rem 1rem 3rem; }

  /* Lesson nav buttons */
  .lesson-nav { gap: .5rem; }
  .lesson-nav .btn { flex: 1; text-align: center; }

  /* Admin */
  .admin-layout { grid-template-columns: 1fr; }
  .admin-nav {
    position: static;
    max-height: none;
    display: flex;
    flex-wrap: wrap;
    gap: .25rem;
    padding: .75rem;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .admin-nav a { border-left: none; border-bottom: 2px solid transparent; padding: .4rem .75rem; font-size: .875rem; border-radius: var(--radius); }
  .admin-nav a.active { border-bottom-color: var(--accent); background: rgba(57,208,184,.07); }
  .admin-brand { display: none; }
  .admin-content { padding: 1.25rem 1rem 3rem; }

  /* Admin tables — horizontal scroll */
  .admin-table { display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }

  /* Admin lesson list — stack buttons */
  .admin-lesson-list li { flex-direction: column; align-items: flex-start; gap: .5rem; }
  .admin-section-header { gap: .5rem; }

  /* Admin page header */
  .admin-page-header { flex-wrap: wrap; }

  /* Forms */
  .form-row { flex-direction: column; gap: 0; }

  /* Auth */
  .auth-wrap { padding: 2rem 0; }
  .auth-box { padding: 1.75rem 1.25rem; border-left: none; border-right: none; border-radius: 0; }

  /* Dashboard */
  .dashboard-wrap { padding: 1.5rem 1rem 3rem; }
  .dashboard-course-card { flex-direction: column; }
  .dcc-actions { flex-direction: row; align-items: flex-start; width: 100%; }
  .dcc-actions .btn { flex: 1; text-align: center; }

  /* Stat grid */
  .stat-grid { grid-template-columns: repeat(2, 1fr); }

  /* Features grid */
  .features-grid { grid-template-columns: 1fr; }

  /* Paywall box */
  .paywall-box { padding: 1.25rem 1rem; margin: 0 .5rem; }
}

/* ── 480px: phone ──────────────────────────────────────────────────────────── */
@media (max-width: 480px) {

  html { font-size: 15px; }

  /* Nav — only show essential links */
  .brand { font-size: 1rem; }
  .site-header nav { gap: .5rem; }

  /* Hero */
  .hero-section { padding: 2.75rem 1rem 2.5rem; }

  /* Lesson */
  .lesson-content { padding: 1.25rem .875rem 3rem; }

  /* Admin */
  .admin-content { padding: 1rem .875rem 3rem; }
  .stat-grid { grid-template-columns: repeat(2, 1fr); gap: .75rem; }

  /* Tables in md content — scrollable */
  .md-content table { display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }

  /* Code copy button — bigger touch target on phones */
  .code-copy-btn { min-height: 36px; min-width: 72px; font-size: .75rem; padding: .35rem .75rem; }

/* Section/lesson in admin */
  .admin-lesson-list li > div { display: flex; flex-wrap: wrap; gap: .35rem; }
}

/* ---- Paywall (fake blur — no real content sent to browser) ---- */
.paywall-wrap {
  position: relative;
  margin-top: 1.5rem;
}

/* Fake placeholder lines that mimic blurred text */
.paywall-fake {
  filter: blur(4px);
  user-select: none;
  pointer-events: none;
  padding: 1rem 0;
  -webkit-mask-image: linear-gradient(to bottom, rgba(0,0,0,.7) 0%, transparent 90%);
  mask-image: linear-gradient(to bottom, rgba(0,0,0,.7) 0%, transparent 90%);
}
.pf-line {
  height: .85rem;
  background: var(--text2);
  border-radius: 4px;
  margin-bottom: .75rem;
  opacity: .35;
}
.pf-block {
  height: 3.5rem;
  background: var(--surface2);
  border-radius: 6px;
  margin: 1rem 0;
  opacity: .5;
}

.paywall-gate {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}
.paywall-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: .75rem;
  padding: 2rem 2.5rem;
  text-align: center;
  box-shadow: 0 4px 32px rgba(0,0,0,.5);
  max-width: 420px;
  width: 100%;
}
.paywall-msg { margin: 0 0 1.25rem; font-size: 1rem; color: var(--text2); }
.paywall-actions { display: flex; flex-direction: column; gap: .75rem; align-items: center; }
.paywall-actions form { width: 100%; }
.paywall-actions .btn { width: 100%; justify-content: center; }
.paywall-login-hint { margin: .75rem 0 0; font-size: .85rem; color: var(--text3); }

/* ---- User Dashboard ---- */
.dashboard-wrap { padding: 2rem 1rem 4rem; max-width: 860px; }
.dashboard-header { display:flex; align-items:flex-start; justify-content:space-between; margin-bottom:2rem; gap:1rem; flex-wrap:wrap; }
.dashboard-header-actions { display:flex; gap:.5rem; flex-wrap:wrap; align-items:center; }
.dashboard-header h1 { margin:0 0 .25rem; }
.dashboard-course-list { display:flex; flex-direction:column; gap:1rem; margin-top:1rem; }
.dashboard-course-card {
  display:flex; align-items:flex-start; justify-content:space-between;
  gap:1.5rem; padding:1.25rem 1.5rem;
  background:var(--surface); border:1px solid var(--border); border-radius:.75rem;
  flex-wrap:wrap;
}
.card-inactive { opacity:.7; border-style:dashed; }
.dcc-body { flex:1; min-width:0; }
.dcc-title { margin:0 0 .4rem; font-size:1.1rem; }
.dcc-desc  { margin:0 0 .75rem; font-size:.9rem; }
.dcc-meta  { display:flex; flex-wrap:wrap; align-items:center; gap:.5rem; }
.dcc-actions { display:flex; flex-direction:column; gap:.5rem; align-items:flex-end; flex-shrink:0; }
.badge { font-size:.75rem; font-weight:600; padding:.2em .65em; border-radius:999px; }
.badge-green { background:#0d3b2a; color:#4ade80; }
.badge-blue  { background:#0d2844; color:#60a5fa; }
.badge-red   { background:#3b0d0d; color:#f87171; }
.badge-gray  { background:var(--surface2); color:var(--text2); }
.empty-state { text-align:center; padding:4rem 1rem; color:var(--text2); }
.empty-state p { margin-bottom:1rem; font-size:1.1rem; }

/* ---- Hero ---- */
.hero-section {
  background: linear-gradient(135deg, #060d1a 0%, #0a1628 60%, #0d1f35 100%);
  border-bottom: 1px solid var(--border);
  padding: 5rem 1rem 4rem;
  text-align: center;
}
.hero-inner { max-width: 680px; margin: 0 auto; }
.hero-badge {
  display: inline-block;
  font-size: .75rem; font-weight: 600; letter-spacing: .08em; text-transform: uppercase;
  color: var(--accent); border: 1px solid var(--accent);
  padding: .25em .75em; border-radius: 999px; margin-bottom: 1.25rem;
}
.hero-title { font-size: clamp(2rem, 5vw, 3.25rem); font-weight: 600; margin: 0 0 1rem; line-height: 1.15; }
.hero-sub { font-size: 1.1rem; color: var(--text2); margin: 0 0 2rem; }
.hero-actions { display: flex; gap: .75rem; justify-content: center; flex-wrap: wrap; margin-bottom: 1.75rem; }
.btn-lg { padding: .75rem 1.75rem; font-size: 1rem; }
.btn-ghost {
  background: transparent; color: var(--text);
  border: 1px solid var(--border);
}
.btn-ghost:hover { background: var(--surface); border-color: var(--text2); }
.hero-trust { display: flex; gap: 1.25rem; justify-content: center; flex-wrap: wrap; font-size: .8rem; color: var(--text3); }

/* ---- Course sections ---- */
.section-courses { padding: 3.5rem 0; }
.section-title { font-size: 1.5rem; margin: 0 0 1.5rem; }
.page-courses { padding: 3rem 1rem; }
.page-header { margin-bottom: 2rem; }
.page-header h1 { margin: 0 0 .4rem; }
.course-card { display: flex; flex-direction: column; }
.course-card-body { flex: 1; }
.price-label { font-size: .8rem; color: var(--text3); margin-left: .2rem; }

/* ---- Features ---- */
.features-section { padding: 3rem 0 4.5rem; border-top: 1px solid var(--border); }
.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px,1fr)); gap: 1.5rem; }
.feature-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: .75rem; padding: 1.5rem;
}
.feature-icon { font-size: 1.75rem; margin-bottom: .75rem; }
.feature-card h3 { margin: 0 0 .5rem; font-size: 1rem; }
.feature-card p { margin: 0; font-size: .9rem; color: var(--text2); line-height: 1.6; }

/* ── Syntax highlighting — layout only, colors from /assets/css/hljs.css ────── */
pre code.hljs {
  font-family: var(--mono);
  font-size: 1rem;
  line-height: 1.65;
  -webkit-overflow-scrolling: touch;
  padding: 1rem 1.25rem;
}

/* ── Site footer ─────────────────────────────────────────────────────────────── */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg2);
  margin-top: 4rem;
}
.footer-inner {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 3rem;
  padding: 3rem 1.5rem 2.5rem;
  align-items: flex-start;
}
.footer-brand .brand { font-size: 1.125rem; }
.footer-tagline { color: var(--text3); font-size: .875rem; margin: .4rem 0 0; max-width: 280px; }
.footer-nav { display: flex; gap: 3rem; }
.footer-col { display: flex; flex-direction: column; gap: .5rem; }
.footer-col-title { font-size: .75rem; font-weight: 600; text-transform: uppercase; letter-spacing: .07em; color: var(--text3); margin-bottom: .25rem; }
.footer-col a { color: var(--text2); font-size: .9rem; }
.footer-col a:hover { color: var(--text); text-decoration: none; }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 1rem 1.5rem;
  font-size: .8125rem;
  color: var(--text3);
}
.footer-bottom a { color: var(--text3); }
.footer-bottom a:hover { color: var(--text2); }

/* ── Hero Udemy instructor social proof ──────────────────────────────────────── */
.hero-instructor {
  display: inline-flex;
  align-items: center;
  gap: 1rem;
  background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.12);
  border-radius: .75rem;
  padding: .75rem 1.25rem;
  margin-bottom: 2rem;
}
.udemy-bestseller-tag {
  background: #f69c18;
  color: #1c1c1c;
  font-size: .65rem;
  font-weight: 800;
  letter-spacing: .08em;
  padding: .3rem .6rem;
  border-radius: .3rem;
  white-space: nowrap;
  font-family: var(--font-sans);
}
.udemy-instructor-text {
  display: flex;
  flex-direction: column;
  gap: .15rem;
  text-align: left;
}
.udemy-stars {
  color: #f69c18;
  font-size: .95rem;
  letter-spacing: .02em;
}
.udemy-rating {
  color: #fff;
  font-weight: 600;
  margin-left: .2rem;
}
.udemy-label {
  font-size: .85rem;
  color: rgba(255,255,255,.65);
  line-height: 1.3;
}
.udemy-label strong { color: rgba(255,255,255,.9); font-weight: 600; }
.udemy-cred {
  font-size: .78rem;
  color: rgba(255,255,255,.45);
  margin-top: .2rem;
}

/* ── Legal pages ─────────────────────────────────────────────────────────────── */
.legal-page { padding: 3rem 1rem 5rem; }
.legal-wrap { max-width: 720px; }
.legal-wrap h1 { margin-bottom: .4rem; }
.legal-date { color: var(--text3); font-size: .875rem; margin-bottom: 2.5rem; }
.legal-wrap h2 { font-size: 1.15rem; margin: 2rem 0 .5rem; color: var(--text); border-bottom: 1px solid var(--border); padding-bottom: .4rem; }
.legal-wrap h3 { font-size: 1rem; margin: 1.25rem 0 .4rem; color: var(--text2); }
.legal-wrap p { color: var(--text2); line-height: 1.75; margin-bottom: .75rem; }
.legal-wrap ul { color: var(--text2); line-height: 1.75; padding-left: 1.5rem; margin-bottom: .75rem; }
.legal-wrap li { margin-bottom: .35rem; }
.legal-wrap strong { color: var(--text); }

/* ── Footer responsive ───────────────────────────────────────────────────────── */
@media (max-width: 768px) {
  .footer-inner { grid-template-columns: 1fr; gap: 2rem; padding: 2rem 1rem 1.5rem; }
  .footer-nav { flex-wrap: wrap; gap: 1.5rem; }
}

/* ── Language switcher ───────────────────────────────────────────────────────── */
.lang-switcher { position: relative; }
.lang-btn {
  display: inline-flex; align-items: center; gap: .35rem;
  background: transparent; border: 1px solid var(--border);
  border-radius: var(--radius); color: var(--text2);
  font-family: var(--sans); font-size: .85rem;
  padding: .3rem .65rem; cursor: pointer;
  transition: border-color .15s, color .15s;
  white-space: nowrap; width: auto; margin: 0;
}
.lang-btn:hover { border-color: var(--text3); color: var(--text); }
.lang-btn span { display: none; }
@media (min-width: 640px) { .lang-btn span { display: inline; } }
.lang-menu {
  display: none; position: absolute; right: 0; top: calc(100% + .4rem);
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: var(--radius); list-style: none;
  min-width: 160px; z-index: 200;
  box-shadow: 0 8px 24px rgba(0,0,0,.4);
  padding: .25rem 0;
}
.lang-switcher:hover .lang-menu,
.lang-switcher:focus-within .lang-menu { display: block; }
.lang-menu li { margin: 0; }
.lang-menu li.active button { color: var(--accent); }
.lang-menu li button {
  display: block; width: 100%; text-align: left;
  padding: .45rem .85rem; background: none;
  border: none; color: var(--text2); font-family: var(--sans);
  font-size: .875rem; cursor: pointer; margin: 0;
}
.lang-menu li button:hover { background: var(--bg3); color: var(--text); }