:root {
  --bg: #f3f6fb;
  --bg-alt: #e8eef8;
  --surface: #ffffff;
  --ink: #1a2332;
  --muted: #5a6a7e;
  --line: #d4dde8;
  --brand: #1e6fe8;
  --brand-deep: #0f4cb8;
  --brand-soft: #dce9fc;
  --accent: #00a3c4;
  --header: #121820;
  --header-ink: #f2f5f9;
  --danger: #c62828;
  --radius: 12px;
  --shadow: 0 10px 30px rgba(18, 24, 32, 0.08);
  --max: 1120px;
  --nav-h: 68px;
  --font-display: "Be Vietnam Pro", "Segoe UI", sans-serif;
  --font-body: "Be Vietnam Pro", "Segoe UI", sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink);
  background:
    radial-gradient(ellipse 80% 50% at 10% -10%, rgba(30, 111, 232, 0.12), transparent 55%),
    radial-gradient(ellipse 60% 40% at 100% 0%, rgba(0, 163, 196, 0.1), transparent 50%),
    linear-gradient(180deg, #eef3fa 0%, var(--bg) 28%, #f7f9fc 100%);
  line-height: 1.65;
  min-height: 100vh;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--brand-deep);
  text-decoration: none;
}

a:hover {
  color: var(--brand);
}

ul {
  padding-left: 1.2rem;
}

.container {
  width: min(100% - 2rem, var(--max));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--nav-h);
  background: rgba(18, 24, 32, 0.96);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  isolation: isolate;
}

.nav-inner {
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.logo-link {
  display: flex;
  align-items: center;
  height: 100%;
  flex-shrink: 0;
}

.logo-link img {
  height: 40px;
  width: auto;
  max-height: calc(var(--nav-h) - 20px);
  object-fit: contain;
}

.nav-desktop {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-desktop a {
  color: var(--header-ink);
  font-size: 0.92rem;
  font-weight: 500;
  padding: 0.45rem 0.7rem;
  border-radius: 8px;
  transition: background 0.2s, color 0.2s;
}

.nav-desktop a:hover,
.nav-desktop a.active {
  background: rgba(255, 255, 255, 0.08);
  color: #fff;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.65rem 1.15rem;
  border-radius: 10px;
  font-weight: 600;
  font-size: 0.92rem;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s, background 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #fff;
  box-shadow: 0 8px 20px rgba(30, 111, 232, 0.28);
}

.btn-primary:hover {
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--header-ink);
  border-color: rgba(255, 255, 255, 0.22);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.08);
  color: #fff;
}

.btn-outline {
  background: var(--surface);
  color: var(--brand-deep);
  border-color: var(--brand-soft);
}

.menu-toggle {
  display: none;
  align-items: center;
  gap: 0.4rem;
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #fff;
  padding: 0.45rem 0.7rem;
  border-radius: 8px;
  cursor: pointer;
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
}

.menu-toggle svg {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
}

.mobile-panel {
  display: none;
  position: absolute;
  top: var(--nav-h);
  left: 0;
  right: 0;
  background: #0f141c;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  padding: 0.75rem 1rem 1.1rem;
}

.mobile-panel.open {
  display: block;
  animation: slideDown 0.25s ease;
}

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

.mobile-panel a {
  display: block;
  color: #e8eef8;
  padding: 0.75rem 0.5rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.mobile-auth {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.85rem;
}

.mobile-auth .btn {
  flex: 1;
}

.hero {
  position: relative;
  min-height: clamp(360px, 62vh, 560px);
  display: grid;
  align-items: end;
  overflow: hidden;
  background: #0d1218;
}

.hero-media {
  position: absolute;
  inset: 0;
}

.hero-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  animation: heroZoom 18s ease-in-out infinite alternate;
}

@keyframes heroZoom {
  from {
    transform: scale(1);
  }
  to {
    transform: scale(1.06);
  }
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, rgba(8, 12, 18, 0.88) 0%, rgba(8, 12, 18, 0.55) 48%, rgba(8, 12, 18, 0.35) 100%),
    linear-gradient(180deg, rgba(8, 12, 18, 0.25) 0%, rgba(8, 12, 18, 0.75) 100%);
}

.hero-content {
  position: relative;
  z-index: 1;
  padding: 4.5rem 0 3.2rem;
  color: #fff;
  max-width: 640px;
}

.hero-brand {
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 6vw, 3.6rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  margin: 0 0 0.6rem;
  line-height: 1.05;
  background: linear-gradient(90deg, #fff 20%, #9fd0ff 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero h1 {
  font-size: clamp(1.15rem, 2.4vw, 1.45rem);
  font-weight: 600;
  margin: 0 0 0.75rem;
  line-height: 1.35;
  color: #e8f0ff;
}

.hero p {
  margin: 0 0 1.35rem;
  color: rgba(232, 240, 255, 0.85);
  font-size: 1rem;
  max-width: 34rem;
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.section {
  padding: 3.5rem 0;
}

.section-alt {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.55), rgba(232, 238, 248, 0.7));
}

.section-head {
  margin-bottom: 1.75rem;
}

.section-head h2 {
  margin: 0 0 0.45rem;
  font-size: clamp(1.45rem, 3vw, 1.85rem);
  letter-spacing: -0.02em;
}

.section-head p {
  margin: 0;
  color: var(--muted);
  max-width: 40rem;
}

.intro-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 2rem;
  align-items: center;
}

.intro-copy p {
  color: var(--muted);
  margin: 0 0 1rem;
}

.intro-visual {
  position: relative;
}

.intro-visual img {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
}

.category-item {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
  transition: transform 0.25s ease;
}

.category-item:hover {
  transform: translateY(-4px);
}

.category-item img {
  width: 100%;
  aspect-ratio: 16 / 11;
  object-fit: cover;
}

.category-item span {
  display: block;
  padding: 0.85rem 1rem 1rem;
  font-weight: 700;
  color: var(--ink);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.15rem;
}

.article-card {
  background: var(--surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  border: 1px solid rgba(212, 221, 232, 0.7);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 36px rgba(18, 24, 32, 0.12);
}

.article-card img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.article-card .body {
  padding: 1rem 1.05rem 1.2rem;
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  flex: 1;
}

.article-card .tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--brand);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.article-card h3 {
  margin: 0;
  font-size: 1.05rem;
  line-height: 1.35;
}

.article-card h3 a {
  color: var(--ink);
}

.article-card h3 a:hover {
  color: var(--brand);
}

.article-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
  flex: 1;
}

.article-card .meta {
  font-size: 0.8rem;
  color: #7a8799;
  margin-top: 0.35rem;
}

.faq-list {
  display: grid;
  gap: 0.75rem;
  max-width: 800px;
}

.faq-item {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0.2rem 1rem;
}

.faq-item summary {
  cursor: pointer;
  font-weight: 650;
  padding: 0.95rem 0;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  float: right;
  color: var(--brand);
  font-weight: 700;
}

.faq-item[open] summary::after {
  content: "–";
}

.faq-item p {
  margin: 0 0 1rem;
  color: var(--muted);
}

.page-hero {
  padding: 2.4rem 0 1.4rem;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.7), transparent);
}

.page-hero h1 {
  margin: 0 0 0.55rem;
  font-size: clamp(1.6rem, 3.5vw, 2.2rem);
  letter-spacing: -0.02em;
}

.page-hero p {
  margin: 0;
  color: var(--muted);
  max-width: 46rem;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 0.85rem;
}

.breadcrumb a {
  color: var(--muted);
}

.breadcrumb span {
  opacity: 0.5;
}

.content-wrap {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 2rem;
  padding: 2.2rem 0 3.5rem;
}

.content-main {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.6rem 1.5rem;
  box-shadow: var(--shadow);
  border: 1px solid rgba(212, 221, 232, 0.65);
}

.content-main h2 {
  margin-top: 1.8rem;
  font-size: 1.35rem;
}

.content-main h3 {
  margin-top: 1.4rem;
  font-size: 1.1rem;
}

.content-main p,
.content-main li {
  color: var(--muted);
}

.cover {
  border-radius: 10px;
  overflow: hidden;
  margin: 0 0 1.25rem;
}

.cover img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.side-box {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.1rem;
  box-shadow: var(--shadow);
  border: 1px solid rgba(212, 221, 232, 0.65);
}

.side-box h3 {
  margin: 0 0 0.85rem;
  font-size: 1rem;
}

.side-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.7rem;
}

.side-list a {
  color: var(--ink);
  font-weight: 560;
  font-size: 0.92rem;
}

.side-list a:hover {
  color: var(--brand);
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin-top: 1.5rem;
}

.brand-strip {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: 0.75rem;
  align-items: center;
}

.brand-strip img {
  width: 100%;
  height: 48px;
  object-fit: contain;
  filter: grayscale(0.15);
  opacity: 0.9;
  transition: opacity 0.2s, filter 0.2s;
}

.brand-strip img:hover {
  filter: none;
  opacity: 1;
}

.promo-row {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 1.25rem;
  align-items: center;
}

.promo-row img {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.site-footer {
  background: #10161f;
  color: #c5d0de;
  padding: 3rem 0 1.5rem;
  margin-top: 1rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.site-footer h3 {
  color: #fff;
  margin: 0 0 0.85rem;
  font-size: 1rem;
}

.site-footer p,
.site-footer a {
  color: #a8b6c8;
  font-size: 0.92rem;
}

.site-footer a:hover {
  color: #fff;
}

.footer-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.45rem;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding-top: 1.1rem;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: #7f8fa3;
}

.error-page {
  min-height: calc(100vh - var(--nav-h));
  display: grid;
  place-items: center;
  text-align: center;
  padding: 3rem 1rem;
}

.error-page h1 {
  font-size: clamp(3rem, 10vw, 5rem);
  margin: 0;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.error-page p {
  color: var(--muted);
  max-width: 28rem;
  margin: 0.75rem auto 1.4rem;
}

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

.reveal.visible {
  opacity: 1;
  transform: none;
}

@media (max-width: 980px) {
  .nav-desktop,
  .nav-actions {
    display: none;
  }

  .menu-toggle {
    display: inline-flex;
    margin-left: auto;
  }

  .intro-grid,
  .content-wrap,
  .promo-row,
  .footer-grid {
    grid-template-columns: 1fr;
  }

  .category-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .card-grid {
    grid-template-columns: 1fr 1fr;
  }

  .brand-strip {
    grid-template-columns: repeat(4, 1fr);
  }

  .related-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  :root {
    --nav-h: 60px;
  }

  .logo-link img {
    height: 34px;
  }

  .hero-content {
    padding: 3.2rem 0 2.4rem;
  }

  .card-grid,
  .category-grid {
    grid-template-columns: 1fr;
  }

  .brand-strip {
    grid-template-columns: repeat(4, 1fr);
  }

  .content-main {
    padding: 1.15rem 1rem;
  }

  .section {
    padding: 2.5rem 0;
  }
}