/* ==========================================================================
   DVD Creator and DVD Burner Plus — Online Tutorial
   Dark theme, matched to the app's own visual language.
   Layout: [ad rail] [tutorial nav] content [related apps] — sticky rails.
   ========================================================================== */

:root {
  --bg: #0b101b;
  --bg-soft: #0e1524;
  --panel: #121a2b;
  --card: #17223a;
  --card-hover: #1c2945;
  --border: rgba(147, 163, 205, 0.16);
  --border-strong: rgba(147, 163, 205, 0.3);
  --text: #e9eef7;
  --muted: #93a0bc;
  --faint: #6b7897;
  --accent: #4c82ff;
  --accent-soft: rgba(76, 130, 255, 0.14);
  --accent-border: rgba(76, 130, 255, 0.45);
  --ok: #2eae63;
  --warn: #e3a93a;
  --danger: #e5534d;
  --radius: 12px;
  --radius-sm: 8px;
  --font-display: "Segoe UI Variable Display", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-body: "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-mono: "Cascadia Code", Consolas, "Courier New", monospace;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --header-h: 62px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(1100px 500px at 85% -10%, rgba(76, 130, 255, 0.09), transparent 60%),
    radial-gradient(900px 420px at -10% 0%, rgba(76, 130, 255, 0.06), transparent 55%),
    var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

::selection { background: rgba(76, 130, 255, 0.35); }

img { max-width: 100%; }

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

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  line-height: 1.25;
  letter-spacing: -0.01em;
}

/* ------------------------------------------------------------------ header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(11, 16, 27, 0.88);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.site-header-inner {
  max-width: 1700px;
  margin: 0 auto;
  padding: 10px 20px;
  display: flex;
  align-items: center;
  gap: 14px;
}
.brand { display: flex; align-items: center; gap: 10px; min-width: 0; }
.brand img { width: 34px; height: 34px; border-radius: 8px; flex: none; }
.brand-name { font-family: var(--font-display); font-weight: 600; font-size: 15px; white-space: nowrap; }
.brand-name small { display: block; font-size: 11px; color: var(--muted); font-weight: 400; }

.store-btn {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: linear-gradient(180deg, #4c82ff, #2f63d8);
  color: #fff;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 13.5px;
  padding: 9px 16px;
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  box-shadow: 0 4px 14px rgba(47, 99, 216, 0.4);
  white-space: nowrap;
  text-decoration: none !important;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.store-btn:hover { transform: translateY(-1px); box-shadow: 0 6px 18px rgba(47, 99, 216, 0.55); }
.store-btn:active { transform: translateY(0); }
.store-btn svg { flex: none; }
.store-alt { font-size: 11.5px; color: var(--faint); white-space: nowrap; }
@media (max-width: 640px) { .store-alt { display: none; } }

/* -------------------------------------------------------------- site nav */
.site-nav {
  background: var(--bg-soft);
  border-bottom: 1px solid var(--border);
}
.site-nav-inner {
  max-width: 1720px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px;
}
.site-nav a {
  display: inline-block;
  padding: 10px 14px;
  font-family: var(--font-display);
  font-size: 13.5px;
  font-weight: 600;
  color: var(--muted);
  text-decoration: none !important;
  border-radius: 7px;
  transition: color 0.15s, background 0.15s;
}
.site-nav a:hover { color: var(--text); background: var(--panel); }
.site-nav a.on { color: var(--accent); background: var(--accent-soft); }
.site-nav .nav-news {
  margin-left: auto;
  font-size: 12px;
  color: var(--faint);
}
@media (max-width: 900px) { .site-nav .nav-news { display: none; } }

/* -------------------------------------------------------------- shell grid */
.shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 20px;
  max-width: 1680px;
  margin: 0 auto;
  padding: 22px 20px;
  align-items: start;
}

/* side columns: stick to viewport while scrolling */
.ad-rail, .side-nav, .side-apps {
  position: sticky;
  top: calc(var(--header-h) + 22px);
  max-height: calc(100vh - var(--header-h) - 40px);
  overflow-y: auto;
  scrollbar-width: thin;
  min-width: 0;
}
.ad-rail { display: none; }
.side-nav { display: none; }
.side-apps { display: none; }

.layout { min-width: 0; max-width: 860px; width: 100%; margin: 0 auto; }

/* breakpoints: rails appear only when the viewport has room to spare,
   so they never squeeze the reading column below a comfortable width.
   Every rail gets an explicit column - never rely on auto-placement. */
@media (min-width: 1150px) {
  .shell { grid-template-columns: 210px minmax(0, 1fr); }
  .side-nav { display: block; grid-column: 1; grid-row: 1; }
  .layout { grid-column: 2; grid-row: 1; }
}
@media (min-width: 1380px) {
  .shell { grid-template-columns: 210px minmax(0, 1fr) 190px; }
  .side-nav { display: block; grid-column: 1; grid-row: 1; }
  .layout { grid-column: 2; grid-row: 1; }
  .side-apps { display: block; grid-column: 3; grid-row: 1; }
}
@media (min-width: 1680px) {
  .shell { grid-template-columns: 170px 210px minmax(0, 1fr) 190px; }
  .ad-rail { display: flex; grid-column: 1; grid-row: 1; }
  .side-nav { display: block; grid-column: 2; grid-row: 1; }
  .layout { grid-column: 3; grid-row: 1; }
  .side-apps { display: block; grid-column: 4; grid-row: 1; }
}

/* --------------------------------------------------------- side: ad rail */
/* No box, no label: when an ad renders it shows; otherwise the column is
   plain site background. */
.ad-rail { align-items: flex-start; }
.ad-rail .ad-box {
  width: 100%;
  min-width: 0;
  overflow: hidden;
}

/* ---------------------------------------------------- side: tutorial nav */
.side-nav .nav-title {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--faint);
  padding: 6px 4px 10px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 10px;
}
.side-nav ul { list-style: none; margin: 0; padding: 0; }
.side-nav li { margin: 2px 0; }
.side-nav a {
  display: block;
  padding: 9px 12px;
  border-radius: 9px;
  border: 1px solid transparent;
  color: var(--muted);
  font-size: 13.5px;
  line-height: 1.35;
  text-decoration: none !important;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}
.side-nav a .n {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--faint);
  margin-right: 6px;
}
.side-nav a:hover { background: var(--panel); color: var(--text); }
.side-nav a.current {
  background: var(--accent-soft);
  border-color: var(--accent-border);
  color: var(--accent);
}
.side-nav a.current .n { color: var(--accent); }

/* ------------------------------------------------ side: related apps */
.side-apps .apps-title {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--faint);
  padding: 6px 4px 10px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 10px;
}
.side-apps ul { list-style: none; margin: 0; padding: 0; }
.side-apps li { margin: 8px 0; }
.side-apps a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 10px;
  border-radius: 9px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  font-size: 13px;
  font-weight: 600;
  line-height: 1.3;
  text-decoration: none !important;
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
}
.side-apps a:hover { border-color: var(--accent-border); background: var(--card-hover); transform: translateY(-1px); }
.side-apps a img {
  width: 36px; height: 36px;
  border-radius: 7px;
  object-fit: cover;
  background: #fff;
  flex: none;
}
.side-apps a span { min-width: 0; }
.side-apps a small { display: block; font-weight: 400; font-size: 11px; color: var(--muted); }
.side-apps .apps-ad { margin-top: 14px; min-width: 0; max-width: 100%; overflow: hidden; }

/* --------------------------------------------------------------- hero */
.hero { padding: 40px 0 14px; text-align: center; }
.hero-eyebrow {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  border: 1px solid var(--accent-border);
  background: var(--accent-soft);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 14px;
}
.hero h1 { font-size: clamp(28px, 4.4vw, 44px); margin: 0 0 10px; }
.hero p { color: var(--muted); max-width: 640px; margin: 0 auto; font-size: 16.5px; }
.hero .store-btn { margin: 22px auto 0; font-size: 15px; padding: 12px 22px; }

/* --------------------------------------------------------------- stepper */
.stepper {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 6px;
  margin: 24px auto 8px;
  max-width: 900px;
}
.step {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--muted);
  font-size: 13px;
  font-family: var(--font-display);
  font-weight: 600;
  text-decoration: none !important;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}
.step:hover { border-color: var(--accent-border); color: var(--text); }
.step .dot {
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--faint);
  flex: none;
}
.step.current {
  border-color: var(--accent-border);
  background: var(--accent-soft);
  color: var(--accent);
}
.step.current .dot { background: var(--accent); box-shadow: 0 0 0 3px rgba(76, 130, 255, 0.25); }
.step.done .dot { background: var(--ok); }
@media (max-width: 720px) { .stepper { gap: 4px; } .step { padding: 6px 10px; font-size: 12px; } }

/* --------------------------------------------------------------- page head */
.page-head { display: flex; gap: 18px; align-items: flex-start; margin: 30px 0 8px; }
.page-num {
  flex: none;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent-border);
  border-radius: 10px;
  padding: 8px 12px;
  line-height: 1;
}
.page-head h1 { margin: 0 0 6px; font-size: clamp(22px, 3vw, 30px); }
.page-head .sub { color: var(--muted); margin: 0; font-size: 15px; }

/* --------------------------------------------------------------- content */
.content { max-width: 860px; }

.section { margin: 32px 0; }
.section > h2 {
  font-size: 22px;
  margin: 0 0 6px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.section > h2 .k {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent-border);
  padding: 2px 8px;
  border-radius: 6px;
}
.section > p.lead { color: var(--muted); margin: 4px 0 18px; }
.section h3 { font-size: 17px; margin: 26px 0 8px; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin: 14px 0;
}

.figure {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px;
  margin: 16px 0;
}
.figure img {
  display: block;
  width: 100%;
  border-radius: 8px;
  border: 1px solid var(--border);
}
.figure figcaption {
  font-size: 13px;
  color: var(--muted);
  text-align: center;
  padding: 8px 4px 2px;
}
.figure figcaption b { color: var(--text); font-weight: 600; }

ul.tick, ol.steps { margin: 10px 0 10px 4px; padding-left: 22px; }
ul.tick li { margin: 6px 0; }
ol.steps > li { margin: 12px 0; padding-left: 4px; }
ol.steps > li::marker {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--accent);
}

kbd, .mono { font-family: var(--font-mono); font-size: 0.92em; background: var(--panel); border: 1px solid var(--border); border-radius: 5px; padding: 1px 6px; }

.callout {
  border-radius: var(--radius-sm);
  padding: 12px 16px 12px 44px;
  margin: 14px 0;
  font-size: 14.5px;
  position: relative;
  border: 1px solid;
}
.callout::before {
  position: absolute;
  left: 14px;
  top: 12px;
  font-size: 17px;
  line-height: 1;
}
.callout.tip { background: rgba(46, 174, 99, 0.1); border-color: rgba(46, 174, 99, 0.4); color: #c9f0d9; }
.callout.tip::before { content: "✓"; color: var(--ok); }
.callout.warn { background: rgba(227, 169, 58, 0.09); border-color: rgba(227, 169, 58, 0.4); color: #f4e2bc; }
.callout.warn::before { content: "!"; color: var(--warn); font-weight: 700; }

.checklist { list-style: none; padding: 0; margin: 10px 0; }
.checklist li { padding: 7px 0 7px 30px; position: relative; border-bottom: 1px dashed var(--border); }
.checklist li:last-child { border-bottom: 0; }
.checklist li::before {
  content: "";
  position: absolute;
  left: 4px; top: 12px;
  width: 13px; height: 13px;
  border-radius: 4px;
  border: 2px solid var(--border-strong);
}
.checklist li.checked::before { background: var(--ok); border-color: var(--ok); box-shadow: inset 0 0 0 3px var(--card); }
.checklist li b { color: var(--text); }

dl.props { margin: 12px 0; }
dl.props dt { font-family: var(--font-display); font-weight: 600; font-size: 14px; margin: 14px 0 2px; color: var(--text); }
dl.props dd { margin: 0 0 4px; color: var(--muted); font-size: 14.5px; }
dl.props dd .val { color: var(--text); font-family: var(--font-mono); font-size: 0.92em; }

/* --------------------------------------------------------------- Q&A nav */
.qa-nav { margin: 26px 0; }
.qa-nav h2 { font-size: 17px; margin: 0 0 10px; color: var(--muted); font-weight: 600; }
.qa-list { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 10px; }
.qa-list a {
  display: block;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  font-size: 14px;
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
}
.qa-list a:hover { border-color: var(--accent-border); background: var(--card-hover); transform: translateY(-1px); }
.qa-list a .q { display: block; font-weight: 600; margin-bottom: 2px; }
.qa-list a .p { display: block; color: var(--muted); font-size: 12.5px; }

/* --------------------------------------------------------------- pagination */
.pagination {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin: 42px 0 10px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
}
.pagination .btn {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 14px;
  color: var(--text);
  background: var(--panel);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  padding: 9px 16px;
  text-decoration: none !important;
  transition: border-color 0.15s, background 0.15s;
}
.pagination .btn:hover { border-color: var(--accent-border); background: var(--card-hover); }
.pagination .btn.disabled { opacity: 0.35; pointer-events: none; }
.pagination .nums { display: flex; gap: 6px; flex-wrap: wrap; justify-content: center; }
.pagination .nums a, .pagination .nums span {
  min-width: 34px;
  text-align: center;
  padding: 7px 9px;
  border-radius: 7px;
  font-size: 13.5px;
  font-family: var(--font-display);
  color: var(--muted);
  text-decoration: none;
  border: 1px solid transparent;
}
.pagination .nums a:hover { color: var(--text); border-color: var(--border-strong); }
.pagination .nums span.on { background: var(--accent); color: #fff; font-weight: 700; }
@media (max-width: 560px) { .pagination { flex-wrap: wrap; } }

/* --------------------------------------------------------------- ad inline */
.ad-inline {
  margin: 24px 0;
  min-width: 0;
  max-width: 100%;
  overflow: hidden;
}

/* --------------------------------------------------------------- footer */
.site-footer {
  margin-top: 50px;
  border-top: 1px solid var(--border);
  background: var(--bg-soft);
}
.site-footer-inner { max-width: 1720px; margin: 0 auto; padding: 34px 20px 26px; }
.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 28px;
}
.footer-grid h4 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--faint); margin: 0 0 10px; }
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin: 6px 0; }
.footer-grid a { color: var(--muted); font-size: 14px; }
.footer-grid a:hover { color: var(--text); }
.related-apps li { display: flex; align-items: center; gap: 10px; }
.related-apps img { width: 34px; height: 34px; border-radius: 6px; object-fit: cover; background: #fff; border: 1px solid var(--border); }
.footer-bottom {
  margin-top: 26px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  gap: 8px 22px;
  justify-content: space-between;
  font-size: 12.5px;
  color: var(--faint);
}
.footer-bottom a { color: var(--faint); }

/* --------------------------------------------------------------- responsive */
@media (max-width: 900px) {
  .hero { padding-top: 26px; }
  .content { max-width: 100%; }
  .shell { padding: 16px 14px; }
}
@media (max-width: 560px) {
  .brand-name small { display: none; }
  .section > h2 { font-size: 19px; }
  .card { padding: 14px; }
  .page-head { flex-direction: column; gap: 8px; }
}

/* --------------------------------------------------------------- motion */
@media (prefers-reduced-motion: no-preference) {
  .hero .store-btn { animation: fade-up 0.5s ease both; }
  @keyframes fade-up {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
  }
}