:root {
  --bg-primary: #0f0f1a;
  --bg-secondary: #1a1a2e;
  --bg-card: rgba(30, 30, 50, 0.72);
  --bg-glass: rgba(255, 255, 255, 0.06);
  --bg-glass-hover: rgba(255, 255, 255, 0.11);
  --text-primary: #eaeaf2;
  --text-secondary: #a8a8c0;
  --text-muted: #6e6e8a;
  --accent-1: #7b5cff;
  --accent-2: #ff5c8a;
  --accent-3: #5cd6ff;
  --accent-gradient: linear-gradient(135deg, #7b5cff 0%, #ff5c8a 55%, #ffa45c 100%);
  --accent-gradient-2: linear-gradient(120deg, #5cd6ff 0%, #7b5cff 100%);
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-glass: rgba(255, 255, 255, 0.13);
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.35);
  --shadow-glow: 0 0 40px rgba(123, 92, 255, 0.22);
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --transition-fast: 0.22s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.42s cubic-bezier(0.22, 1, 0.36, 1);
  --max-width: 1180px;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #f4f4fa;
    --bg-secondary: #ffffff;
    --bg-card: rgba(255, 255, 255, 0.78);
    --bg-glass: rgba(255, 255, 255, 0.62);
    --bg-glass-hover: rgba(255, 255, 255, 0.88);
    --text-primary: #1c1c2e;
    --text-secondary: #4a4a66;
    --text-muted: #8a8aa0;
    --border-subtle: rgba(0, 0, 0, 0.07);
    --border-glass: rgba(0, 0, 0, 0.1);
    --shadow-card: 0 8px 32px rgba(80, 80, 140, 0.12);
    --shadow-glow: 0 0 40px rgba(123, 92, 255, 0.14);
  }
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.75;
  font-size: 16px;
  min-height: 100vh;
  overflow-x: hidden;
  background-image:
    radial-gradient(ellipse 80% 50% at 20% -10%, rgba(123, 92, 255, 0.16), transparent),
    radial-gradient(ellipse 60% 40% at 90% 10%, rgba(255, 92, 138, 0.1), transparent),
    radial-gradient(ellipse 70% 50% at 50% 100%, rgba(92, 214, 255, 0.08), transparent);
  background-attachment: fixed;
  transition: background-color var(--transition-smooth), color var(--transition-smooth);
}

::selection {
  background: rgba(123, 92, 255, 0.35);
  color: #fff;
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
  width: 9px;
  height: 9px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--accent-1), var(--accent-2));
  border-radius: 12px;
  border: 2px solid transparent;
  background-clip: padding-box;
}
::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--accent-2), var(--accent-1));
  background-clip: padding-box;
}

/* ===== Header ===== */
header {
  position: sticky;
  top: 0;
  z-index: 1000;
  backdrop-filter: blur(18px) saturate(1.5);
  -webkit-backdrop-filter: blur(18px) saturate(1.5);
  background: rgba(15, 15, 26, 0.72);
  border-bottom: 1px solid var(--border-glass);
  transition: background var(--transition-smooth), box-shadow var(--transition-smooth);
}

@media (prefers-color-scheme: light) {
  header {
    background: rgba(255, 255, 255, 0.72);
  }
}

header nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
  min-height: 64px;
}

header nav > a:first-child {
  font-size: 1.28rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  text-decoration: none;
  white-space: nowrap;
  position: relative;
  transition: transform var(--transition-fast), filter var(--transition-fast);
}

header nav > a:first-child:hover {
  transform: scale(1.04);
  filter: brightness(1.2);
}

header nav > a:first-child::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent-gradient);
  border-radius: 2px;
  transition: width var(--transition-smooth);
}

header nav > a:first-child:hover::after {
  width: 100%;
}

header nav ul {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 2px;
  flex-wrap: wrap;
}

header nav ul li a {
  display: inline-block;
  padding: 8px 14px;
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: var(--radius-sm);
  position: relative;
  transition: color var(--transition-fast), background var(--transition-fast),
    transform var(--transition-fast);
  white-space: nowrap;
}

header nav ul li a::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: var(--radius-sm);
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity var(--transition-fast);
  z-index: -1;
}

header nav ul li a:hover {
  color: #fff;
  transform: translateY(-1px);
}

header nav ul li a:hover::before {
  opacity: 0.18;
}

/* ===== Main ===== */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 24px 80px;
}

/* ===== Article ===== */
article > h1 {
  font-size: clamp(1.6rem, 4.5vw, 2.6rem);
  font-weight: 900;
  line-height: 1.28;
  letter-spacing: -0.03em;
  margin-bottom: 36px;
  padding: 40px 32px;
  border-radius: var(--radius-lg);
  background: var(--accent-gradient);
  background-size: 200% 200%;
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  position: relative;
  overflow: hidden;
  animation: gradientShift 8s ease infinite;
  text-align: center;
}

article > h1::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  background: var(--accent-gradient);
  opacity: 0.08;
  z-index: -1;
}

article > h1::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-glass);
  pointer-events: none;
}

@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

/* ===== Sections ===== */
section {
  margin-bottom: 28px;
  padding: 32px 28px;
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  backdrop-filter: blur(16px) saturate(1.3);
  -webkit-backdrop-filter: blur(16px) saturate(1.3);
  border: 1px solid var(--border-glass);
  box-shadow: var(--shadow-card);
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth),
    border-color var(--transition-smooth);
  opacity: 0;
  transform: translateY(28px);
  animation: fadeInUp 0.7s cubic-bezier(0.22, 1, 0.36, 1) forwards;
}

section:nth-child(1) { animation-delay: 0.05s; }
section:nth-child(2) { animation-delay: 0.1s; }
section:nth-child(3) { animation-delay: 0.15s; }
section:nth-child(4) { animation-delay: 0.2s; }
section:nth-child(5) { animation-delay: 0.25s; }
section:nth-child(6) { animation-delay: 0.3s; }
section:nth-child(7) { animation-delay: 0.35s; }
section:nth-child(8) { animation-delay: 0.4s; }
section:nth-child(9) { animation-delay: 0.45s; }
section:nth-child(10) { animation-delay: 0.5s; }
section:nth-child(11) { animation-delay: 0.55s; }
section:nth-child(12) { animation-delay: 0.6s; }
section:nth-child(13) { animation-delay: 0.65s; }
section:nth-child(14) { animation-delay: 0.7s; }
section:nth-child(15) { animation-delay: 0.75s; }

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

section:hover {
  border-color: rgba(123, 92, 255, 0.3);
  box-shadow: var(--shadow-card), var(--shadow-glow);
}

section h2 {
  font-size: clamp(1.25rem, 3vw, 1.7rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
  padding-bottom: 14px;
  position: relative;
  color: var(--text-primary);
}

section h2::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 56px;
  height: 3px;
  border-radius: 3px;
  background: var(--accent-gradient);
  transition: width var(--transition-smooth);
}

section:hover h2::after {
  width: 100px;
}

section h3 {
  font-size: clamp(1.02rem, 2.2vw, 1.22rem);
  font-weight: 700;
  margin: 24px 0 10px;
  color: var(--text-primary);
  position: relative;
  padding-left: 18px;
}

section h3::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.35em;
  width: 6px;
  height: 1em;
  border-radius: 4px;
  background: var(--accent-gradient);
  transition: height var(--transition-fast), top var(--transition-fast);
}

section h3:hover::before {
  height: 1.3em;
  top: 0.18em;
}

section p {
  color: var(--text-secondary);
  margin-bottom: 12px;
  font-size: 0.96rem;
  line-height: 1.85;
}

section p:last-child {
  margin-bottom: 0;
}

section a {
  color: var(--accent-3);
  text-decoration: none;
  font-weight: 600;
  position: relative;
  transition: color var(--transition-fast);
}

section a::after {
  content: "";
  position: absolute;
  bottom: -1px;
  left: 0;
  width: 100%;
  height: 1px;
  background: var(--accent-3);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform var(--transition-smooth);
}

section a:hover {
  color: var(--accent-2);
}

section a:hover::after {
  transform: scaleX(1);
  transform-origin: left;
  background: var(--accent-2);
}

/* ===== Lists ===== */
section ul,
section ol {
  padding-left: 22px;
  margin: 12px 0;
  color: var(--text-secondary);
}

section li {
  margin-bottom: 8px;
  font-size: 0.95rem;
  line-height: 1.8;
  transition: color var(--transition-fast), transform var(--transition-fast);
}

section li:hover {
  color: var(--text-primary);
  transform: translateX(3px);
}

section li strong {
  color: var(--text-primary);
  font-weight: 700;
}

/* ===== Blockquote ===== */
blockquote {
  margin: 18px 0;
  padding: 18px 22px;
  border-left: 3px solid transparent;
  border-image: var(--accent-gradient) 1;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  background: var(--bg-glass);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  position: relative;
  transition: transform var(--transition-fast), background var(--transition-fast);
}

blockquote:hover {
  transform: translateX(6px);
  background: var(--bg-glass-hover);
}

blockquote p {
  font-style: italic;
  color: var(--text-secondary);
  margin: 0;
}

/* ===== Details / FAQ ===== */
details {
  margin-bottom: 12px;
  border-radius: var(--radius-md);
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  overflow: hidden;
  transition: border-color var(--transition-fast), background var(--transition-fast),
    box-shadow var(--transition-fast);
}

details:hover {
  border-color: rgba(123, 92, 255, 0.25);
  background: var(--bg-glass-hover);
}

details[open] {
  border-color: rgba(123, 92, 255, 0.35);
  box-shadow: 0 4px 20px rgba(123, 92, 255, 0.1);
}

details summary {
  padding: 16px 20px;
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-primary);
  transition: color var(--transition-fast), background var(--transition-fast);
  position: relative;
  user-select: none;
}

details summary::-webkit-details-marker {
  display: none;
}

details summary::before {
  content: "+";
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  min-width: 24px;
  border-radius: 8px;
  background: var(--accent-gradient);
  color: #fff;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1;
  transition: transform var(--transition-smooth), background var(--transition-fast);
}

details[open] summary::before {
  content: "−";
  transform: rotate(180deg);
}

details summary:hover {
  color: var(--accent-2);
}

details p {
  padding: 0 20px 18px 54px;
  color: var(--text-secondary);
  font-size: 0.92rem;
  line-height: 1.85;
  animation: fadeSlide 0.35s ease;
}

@keyframes fadeSlide {
  from {
    opacity: 0;
    transform: translateY(-6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== Nested article (technical articles) ===== */
section > article {
  margin-bottom: 16px;
  padding: 20px 22px;
  border-radius: var(--radius-md);
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth),
    border-color var(--transition-smooth), background var(--transition-fast);
}

section > article:hover {
  transform: translateY(-4px);
  border-color: rgba(123, 92, 255, 0.3);
  box-shadow: 0 12px 36px rgba(0, 0, 0, 0.2), 0 0 24px rgba(123, 92, 255, 0.12);
  background: var(--bg-glass-hover);
}

section > article h3 {
  margin-top: 0;
}

section > article h3::before {
  background: var(--accent-gradient-2);
}

section > article p:first-of-type {
  font-size: 0.84rem;
  color: var(--text-muted);
  margin-bottom: 8px;
}

section > article a {
  display: inline-block;
  margin-top: 6px;
  padding: 7px 18px;
  font-size: 0.86rem;
  border-radius: 999px;
  background: var(--accent-gradient);
  color: #fff !important;
  -webkit-text-fill-color: #fff;
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.02em;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast),
    filter var(--transition-fast);
  position: relative;
  overflow: hidden;
}

section > article a::after {
  display: none;
}

section > article a:hover {
  transform: translateY(-2px) scale(1.03);
  box-shadow: 0 6px 20px rgba(123, 92, 255, 0.4);
  filter: brightness(1.12);
}

/* ===== Sitemap / Links ===== */
#sitemap ul,
#links ul {
  list-style: none;
  padding-left: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

#sitemap ul li,
#links ul li {
  margin-bottom: 0;
}

#sitemap ul li a,
#links ul li a {
  display: inline-block;
  padding: 8px 18px;
  border-radius: 999px;
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 500;
  text-decoration: none;
  transition: all var(--transition-fast);
}

#sitemap ul li a::after,
#links ul li a::after {
  display: none;
}

#sitemap ul li a:hover,
#links ul li a:hover {
  background: var(--accent-gradient);
  color: #fff !important;
  -webkit-text-fill-color: #fff;
  border-color: transparent;
  transform: translateY(-2px) scale(1.04);
  box-shadow: 0 6px 20px rgba(123, 92, 255, 0.35);
}

/* ===== Contact section ===== */
#contact p {
  padding-left: 0;
}

#contact h3 {
  margin-top: 20px;
}

/* ===== Meta info ===== */
#meta-info p {
  font-size: 0.88rem;
  color: var(--text-muted);
}

/* ===== Footer ===== */
footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 24px 48px;
  text-align: center;
  border-top: 1px solid var(--border-subtle);
}

footer p {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-bottom: 16px;
}

footer nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 6px;
}

footer nav a {
  display: inline-block;
  padding: 6px 16px;
  font-size: 0.84rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: 999px;
  border: 1px solid transparent;
  transition: all var(--transition-fast);
}

footer nav a:hover {
  color: var(--accent-2);
  border-color: rgba(255, 92, 138, 0.3);
  background: rgba(255, 92, 138, 0.08);
  transform: translateY(-2px);
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  main {
    padding: 24px 16px 60px;
  }

  section {
    padding: 24px 20px;
    border-radius: var(--radius-md);
  }

  article > h1 {
    padding: 28px 20px;
    border-radius: var(--radius-md);
    margin-bottom: 24px;
  }

  header nav {
    padding: 0 16px;
    min-height: 56px;
  }

  header nav ul {
    gap: 0;
  }

  header nav ul li a {
    padding: 6px 10px;
    font-size: 0.82rem;
  }
}

@media (max-width: 640px) {
  body {
    font-size: 15px;
  }

  main {
    padding: 16px 12px 48px;
  }

  section {
    padding: 20px 16px;
    margin-bottom: 16px;
    border-radius: var(--radius-sm);
  }

  section h2 {
    font-size: 1.18rem;
    margin-bottom: 14px;
    padding-bottom: 10px;
  }

  section h3 {
    font-size: 1rem;
    margin: 18px 0 8px;
  }

  section p {
    font-size: 0.9rem;
    line-height: 1.8;
  }

  article > h1 {
    font-size: 1.35rem;
    padding: 24px 16px;
    margin-bottom: 20px;
    border-radius: var(--radius-sm);
  }

  header nav {
    padding: 0 12px;
    min-height: 52px;
  }

  header nav > a:first-child {
    font-size: 1.05rem;
  }

  header nav ul {
    width: 100%;
    justify-content: flex-start;
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 6px;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

  header nav ul::-webkit-scrollbar {
    display: none;
  }

  header nav ul li a {
    padding: 5px 9px;
    font-size: 0.78rem;
    white-space: nowrap;
  }

  details summary {
    padding: 13px 14px;
    font-size: 0.88rem;
    gap: 8px;
  }

  details summary::before {
    width: 20px;
    height: 20px;
    min-width: 20px;
    font-size: 0.88rem;
    border-radius: 6px;
  }

  details p {
    padding: 0 14px 14px 42px;
    font-size: 0.86rem;
  }

  section > article {
    padding: 16px 14px;
  }

  section > article a {
    padding: 6px 14px;
    font-size: 0.82rem;
  }

  blockquote {
    padding: 14px 16px;
  }

  #sitemap ul,
  #links ul {
    gap: 7px;
  }

  #sitemap ul li a,
  #links ul li a {
    padding: 6px 13px;
    font-size: 0.82rem;
  }

  footer {
    padding: 24px 12px 36px;
  }

  footer nav a {
    padding: 5px 12px;
    font-size: 0.8rem;
  }
}

@media (max-width: 380px) {
  body {
    font-size: 14px;
  }

  section {
    padding: 16px 12px;
  }

  article > h1 {
    font-size: 1.15rem;
    padding: 20px 12px;
  }

  header nav > a:first-child {
    font-size: 0.95rem;
  }

  header nav ul li a {
    padding: 4px 7px;
    font-size: 0.74rem;
  }
}

/* ===== Print ===== */
@media print {
  header,
  footer,
  #sitemap,
  #links {
    display: none;
  }

  body {
    background: #fff;
    color: #000;
  }

  section {
    box-shadow: none;
    border: 1px solid #ddd;
    break-inside: avoid;
    opacity: 1;
    transform: none;
    animation: none;
  }

  article > h1 {
    -webkit-text-fill-color: #000;
    background: none;
  }
}

/* ===== Reduced motion ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  section {
    opacity: 1;
    transform: none;
  }

  article > h1 {
    animation: none;
  }
}

/* ===== Focus visible ===== */
a:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--accent-1);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ===== Touch device hover fix ===== */
@media (hover: none) {
  section:hover {
    border-color: var(--border-glass);
    box-shadow: var(--shadow-card);
  }

  section:hover h2::after {
    width: 56px;
  }

  section > article:hover {
    transform: none;
  }

  blockquote:hover {
    transform: none;
  }
}