:root{
  --brand:#7c3aed;
  --brand-2:#ec4899;
  --brand-3:#06b6d4;
  --brand-soft:rgba(124,58,237,.12);
  --brand-glow:rgba(124,58,237,.35);
  --bg:#ffffff;
  --bg-alt:#f7f5ff;
  --fg:#1f2937;
  --fg-strong:#111827;
  --muted:#6b7280;
  --card:rgba(255,255,255,.72);
  --card-solid:#ffffff;
  --line:rgba(124,58,237,.14);
  --line-strong:rgba(124,58,237,.26);
  --glass:rgba(255,255,255,.55);
  --glass-border:rgba(255,255,255,.65);
  --shadow-sm:0 2px 8px rgba(31,41,55,.06);
  --shadow-md:0 10px 30px rgba(124,58,237,.10);
  --shadow-lg:0 24px 60px rgba(124,58,237,.16);
  --radius-sm:10px;
  --radius:16px;
  --radius-lg:24px;
  --radius-pill:999px;
  --ease:cubic-bezier(.22,.61,.36,1);
  --header-h:68px;
  --grad-main:linear-gradient(120deg,#7c3aed 0%,#a855f7 38%,#ec4899 72%,#f97316 100%);
  --grad-soft:linear-gradient(135deg,rgba(124,58,237,.10),rgba(236,72,153,.08) 55%,rgba(6,182,212,.08));
  --grad-text:linear-gradient(92deg,#7c3aed,#ec4899 55%,#f97316);
  --grad-btn:linear-gradient(120deg,#7c3aed,#a855f7 50%,#ec4899);
  --grad-btn-hover:linear-gradient(120deg,#6d28d9,#9333ea 50%,#db2777);
}

html[data-theme="dark"]{
  --bg:#0b1020;
  --bg-alt:#0f172a;
  --fg:#dbe2f0;
  --fg-strong:#f1f5fb;
  --muted:#94a3b8;
  --card:rgba(30,41,59,.62);
  --card-solid:#16203a;
  --line:rgba(148,163,184,.18);
  --line-strong:rgba(168,85,247,.35);
  --glass:rgba(23,32,54,.55);
  --glass-border:rgba(148,163,184,.22);
  --brand-soft:rgba(168,85,247,.18);
  --brand-glow:rgba(168,85,247,.45);
  --shadow-sm:0 2px 8px rgba(0,0,0,.35);
  --shadow-md:0 12px 34px rgba(0,0,0,.42);
  --shadow-lg:0 28px 70px rgba(0,0,0,.55);
  --grad-soft:linear-gradient(135deg,rgba(124,58,237,.22),rgba(236,72,153,.14) 55%,rgba(6,182,212,.12));
}

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

html{
  scroll-behavior:smooth;
  scroll-padding-top:calc(var(--header-h) + 16px);
  -webkit-text-size-adjust:100%;
}

body{
  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Segoe UI",Roboto,sans-serif;
  font-size:16px;
  line-height:1.8;
  color:var(--fg);
  background:var(--bg);
  background-image:
    radial-gradient(900px 420px at 8% -6%,rgba(124,58,237,.14),transparent 62%),
    radial-gradient(760px 380px at 96% 4%,rgba(236,72,153,.12),transparent 60%),
    radial-gradient(680px 420px at 50% 108%,rgba(6,182,212,.10),transparent 64%);
  background-attachment:fixed;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  overflow-x:hidden;
  transition:background-color .35s var(--ease),color .35s var(--ease);
}

a{
  color:var(--brand);
  text-decoration:none;
  transition:color .25s var(--ease),opacity .25s var(--ease);
}

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

a:focus-visible,
button:focus-visible,
input:focus-visible{
  outline:2px solid var(--brand);
  outline-offset:3px;
  border-radius:6px;
}

img,
svg{
  max-width:100%;
  display:block;
}

::selection{
  background:rgba(124,58,237,.22);
  color:var(--fg-strong);
}

.container{
  width:100%;
  max-width:1180px;
  margin:0 auto;
  padding:0 20px;
}

/* ---------- Header ---------- */
header.site-header{
  position:sticky;
  top:0;
  z-index:100;
  background:var(--glass);
  -webkit-backdrop-filter:saturate(180%) blur(18px);
  backdrop-filter:saturate(180%) blur(18px);
  border-bottom:1px solid var(--line);
  box-shadow:0 1px 0 rgba(255,255,255,.35),0 8px 26px rgba(31,41,55,.05);
  transition:background .35s var(--ease),border-color .35s var(--ease);
}

html[data-theme="dark"] header.site-header{
  box-shadow:0 1px 0 rgba(255,255,255,.04),0 10px 30px rgba(0,0,0,.45);
}

.nav-wrap{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  padding:12px 20px;
  max-width:1180px;
  margin:0 auto;
}

.logo{
  display:inline-flex;
  align-items:center;
  gap:10px;
  font-weight:800;
  font-size:20px;
  letter-spacing:.5px;
  color:var(--fg-strong);
  white-space:nowrap;
}

.logo svg{
  width:38px;
  height:38px;
  border-radius:12px;
  box-shadow:0 6px 18px var(--brand-glow);
  transition:transform .45s var(--ease),box-shadow .45s var(--ease);
}

.logo:hover{
  color:var(--fg-strong);
}

.logo:hover svg{
  transform:rotate(-8deg) scale(1.06);
  box-shadow:0 10px 26px var(--brand-glow);
}

nav.main-nav ul{
  display:flex;
  align-items:center;
  gap:6px;
  list-style:none;
}

nav.main-nav a{
  position:relative;
  display:inline-block;
  padding:8px 12px;
  font-size:15px;
  color:var(--fg);
  border-radius:var(--radius-pill);
  transition:color .25s var(--ease),background .25s var(--ease);
}

nav.main-nav a::after{
  content:"";
  position:absolute;
  left:12px;
  right:12px;
  bottom:3px;
  height:2px;
  border-radius:2px;
  background:var(--grad-text);
  transform:scaleX(0);
  transform-origin:left;
  transition:transform .32s var(--ease);
}

nav.main-nav a:hover{
  color:var(--brand);
  background:var(--brand-soft);
}

nav.main-nav a:hover::after{
  transform:scaleX(1);
}

.nav-tools{
  display:flex;
  align-items:center;
  gap:10px;
}

.search-box{
  display:flex;
  align-items:center;
  border:1px solid var(--line);
  border-radius:var(--radius-pill);
  overflow:hidden;
  background:var(--card);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
  transition:border-color .25s var(--ease),box-shadow .25s var(--ease);
}

.search-box:focus-within{
  border-color:var(--brand);
  box-shadow:0 0 0 4px var(--brand-soft);
}

.search-box input{
  width:130px;
  padding:7px 14px;
  border:none;
  outline:none;
  background:transparent;
  color:var(--fg);
  font-size:14px;
  font-family:inherit;
}

.search-box input::placeholder{
  color:var(--muted);
}

.search-box button{
  border:none;
  padding:7px 14px;
  background:var(--grad-btn);
  color:#fff;
  font-size:14px;
  font-family:inherit;
  cursor:pointer;
  transition:filter .25s var(--ease);
}

.search-box button:hover{
  filter:brightness(1.08);
}

.icon-btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  width:38px;
  height:38px;
  padding:0;
  border:1px solid var(--line);
  border-radius:12px;
  background:var(--card);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
  color:var(--fg);
  font-size:16px;
  line-height:1;
  cursor:pointer;
  transition:transform .25s var(--ease),border-color .25s var(--ease),background .25s var(--ease),box-shadow .25s var(--ease);
}

.icon-btn:hover{
  transform:translateY(-2px);
  border-color:var(--line-strong);
  background:var(--brand-soft);
  box-shadow:var(--shadow-sm);
}

.icon-btn:active{
  transform:translateY(0) scale(.96);
}

.menu-toggle{
  display:none;
}

/* ---------- Breadcrumb ---------- */
.breadcrumb{
  padding:18px 0 4px;
  font-size:14px;
  color:var(--muted);
}

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

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

.breadcrumb span{
  color:var(--fg);
}

/* ---------- Hero ---------- */
.hero{
  position:relative;
  padding:48px 0 72px;
  background:var(--grad-soft);
  border-bottom:1px solid var(--line);
  overflow:hidden;
}

.hero::before,
.hero::after{
  content:"";
  position:absolute;
  border-radius:50%;
  filter:blur(70px);
  pointer-events:none;
  z-index:0;
}

.hero::before{
  width:420px;
  height:420px;
  top:-160px;
  left:-120px;
  background:radial-gradient(circle,rgba(124,58,237,.42),transparent 68%);
  animation:floatA 14s ease-in-out infinite;
}

.hero::after{
  width:380px;
  height:380px;
  right:-120px;
  bottom:-180px;
  background:radial-gradient(circle,rgba(236,72,153,.36),transparent 68%);
  animation:floatB 17s ease-in-out infinite;
}

.hero .container{
  position:relative;
  z-index:1;
}

.hero h1{
  font-size:clamp(26px,4.4vw,42px);
  line-height:1.28;
  font-weight:800;
  letter-spacing:.5px;
  color:var(--fg-strong);
  margin-bottom:18px;
  max-width:960px;
}

.hero h1 span{
  background:var(--grad-text);
  background-size:200% 100%;
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
  animation:shimmer 7s linear infinite;
}

.hero p{
  max-width:780px;
  font-size:17px;
  color:var(--muted);
  margin-bottom:26px;
}

.hero-cta{
  display:flex;
  flex-wrap:wrap;
  gap:14px;
}

.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:12px 28px;
  border:none;
  border-radius:var(--radius-pill);
  font-size:15px;
  font-weight:700;
  font-family:inherit;
  cursor:pointer;
  transition:transform .28s var(--ease),box-shadow .28s var(--ease),background .28s var(--ease),color .28s var(--ease),border-color .28s var(--ease);
}

.btn-primary{
  background:var(--grad-btn);
  background-size:160% 100%;
  color:#fff;
  box-shadow:0 10px 26px var(--brand-glow);
}

.btn-primary:hover{
  color:#fff;
  transform:translateY(-3px);
  background-position:100% 0;
  box-shadow:0 16px 38px var(--brand-glow);
}

.btn-primary:active{
  transform:translateY(-1px) scale(.99);
}

.btn-outline{
  background:var(--glass);
  border:1px solid var(--line-strong);
  color:var(--brand);
  -webkit-backdrop-filter:blur(10px);
  backdrop-filter:blur(10px);
}

.btn-outline:hover{
  color:#fff;
  background:var(--grad-btn);
  border-color:transparent;
  transform:translateY(-3px);
  box-shadow:0 14px 32px var(--brand-glow);
}

/* ---------- Carousel ---------- */
.carousel{
  position:relative;
  margin-top:44px;
  border-radius:var(--radius-lg);
  overflow:hidden;
  box-shadow:var(--shadow-lg);
}

.slides{
  display:flex;
  transition:transform .6s var(--ease);
  will-change:transform;
}

.slide{
  flex:0 0 100%;
  min-width:100%;
  padding:38px 40px;
  background:var(--card);
  -webkit-backdrop-filter:saturate(160%) blur(16px);
  backdrop-filter:saturate(160%) blur(16px);
  border:1px solid var(--glass-border);
  border-radius:var(--radius-lg);
  position:relative;
  overflow:hidden;
}

.slide::before{
  content:"";
  position:absolute;
  inset:0;
  background:linear-gradient(120deg,rgba(124,58,237,.10),transparent 45%,rgba(236,72,153,.10));
  pointer-events:none;
}

.slide h3{
  position:relative;
  font-size:clamp(18px,2.4vw,23px);
  font-weight:800;
  color:var(--fg-strong);
  margin-bottom:10px;
}

.slide p{
  position:relative;
  color:var(--muted);
  font-size:15.5px;
  max-width:820px;
}

.dots{
  display:flex;
  justify-content:center;
  gap:9px;
  margin-top:16px;
}

.dot{
  width:10px;
  height:10px;
  border-radius:var(--radius-pill);
  background:var(--line-strong);
  cursor:pointer;
  transition:width .35s var(--ease),background .35s var(--ease),transform .35s var(--ease);
}

.dot:hover{
  transform:scale(1.2);
}

.dot.active{
  width:28px;
  background:var(--grad-btn);
}

/* ---------- Sections ---------- */
section{
  position:relative;
  padding:64px 0;
  border-bottom:1px solid var(--line);
}

section:nth-of-type(even){
  background:linear-gradient(180deg,transparent,rgba(124,58,237,.035) 40%,transparent);
}

html[data-theme="dark"] section:nth-of-type(even){
  background:linear-gradient(180deg,transparent,rgba(168,85,247,.06) 40%,transparent);
}

section h2{
  position:relative;
  padding-left:18px;
  margin-bottom:24px;
  font-size:clamp(22px,3vw,30px);
  font-weight:800;
  line-height:1.35;
  letter-spacing:.4px;
  color:var(--fg-strong);
}

section h2::before{
  content:"";
  position:absolute;
  left:0;
  top:8px;
  bottom:8px;
  width:6px;
  border-radius:4px;
  background:var(--grad-text);
  box-shadow:0 0 16px var(--brand-glow);
}

section h3{
  margin:28px 0 12px;
  font-size:clamp(18px,2.2vw,21px);
  font-weight:700;
  color:var(--fg-strong);
}

section h4{
  margin:18px 0 8px;
  font-size:16.5px;
  font-weight:700;
  color:var(--brand);
}

section p{
  margin-bottom:14px;
  color:var(--fg);
}

section p.lead{
  max-width:880px;
  font-size:16.5px;
  color:var(--muted);
  margin-bottom:26px;
}

/* ---------- Grids ---------- */
.grid{
  display:grid;
  gap:22px;
}

.grid-2{
  grid-template-columns:repeat(2,minmax(0,1fr));
}

.grid-3{
  grid-template-columns:repeat(3,minmax(0,1fr));
}

.grid-4{
  grid-template-columns:repeat(4,minmax(0,1fr));
}

/* ---------- Cards ---------- */
.card{
  position:relative;
  padding:24px;
  background:var(--card);
  -webkit-backdrop-filter:saturate(160%) blur(14px);
  backdrop-filter:saturate(160%) blur(14px);
  border:1px solid var(--line);
  border-radius:var(--radius);
  box-shadow:var(--shadow-sm);
  overflow:hidden;
  transition:transform .4s var(--ease),box-shadow .4s var(--ease),border-color .4s var(--ease),background .4s var(--ease);
}

.card::after{
  content:"";
  position:absolute;
  inset:0;
  border-radius:inherit;
  background:linear-gradient(135deg,rgba(124,58,237,.10),transparent 42%,rgba(236,72,153,.10));
  opacity:0;
  transition:opacity .4s var(--ease);
  pointer-events:none;
}

.card:hover{
  transform:translateY(-6px);
  border-color:var(--line-strong);
  box-shadow:var(--shadow-md);
}

.card:hover::after{
  opacity:1;
}

.card > *{
  position:relative;
  z-index:1;
}

.card h3{
  margin-top:0;
  font-size:19px;
}

.card h4{
  margin-top:0;
}

.card p:last-child{
  margin-bottom:0;
}

.card svg{
  width:52px;
  height:52px;
  margin-bottom:14px;
  border-radius:14px;
  box-shadow:0 8px 20px rgba(124,58,237,.20);
  transition:transform .45s var(--ease);
}

.card:hover svg{
  transform:translateY(-3px) rotate(-4deg) scale(1.05);
}

/* ---------- Stats ---------- */
.stat{
  padding:26px 18px;
  text-align:center;
  background:var(--card);
  -webkit-backdrop-filter:saturate(160%) blur(14px);
  backdrop-filter:saturate(160%) blur(14px);
  border:1px solid var(--line);
  border-radius:var(--radius);
  box-shadow:var(--shadow-sm);
  transition:transform .4s var(--ease),box-shadow .4s var(--ease),border-color .4s var(--ease);
}

.stat:hover{
  transform:translateY(-5px);
  border-color:var(--line-strong);
  box-shadow:var(--shadow-md);
}

.stat .num{
  font-size:clamp(28px,3.4vw,36px);
  font-weight:800;
  line-height:1.2;
  letter-spacing:.5px;
  background:var(--grad-text);
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
}

.stat .label{
  margin-top:6px;
  font-size:14px;
  color:var(--muted);
}

/* ---------- Articles ---------- */
.article-list{
  display:grid;
  gap:18px;
}

.article-item{
  position:relative;
  padding:22px 24px;
  background:var(--card);
  -webkit-backdrop-filter:saturate(160%) blur(14px);
  backdrop-filter:saturate(160%) blur(14px);
  border:1px solid var(--line);
  border-radius:var(--radius);
  box-shadow:var(--shadow-sm);
  transition:transform .35s var(--ease),box-shadow .35s var(--ease),border-color .35s var(--ease);
}

.article-item::before{
  content:"";
  position:absolute;
  left:0;
  top:18px;
  bottom:18px;
  width:4px;
  border-radius:4px;
  background:var(--grad-text);
  opacity:0;
  transform:scaleY(.4);
  transition:opacity .35s var(--ease),transform .35s var(--ease);
}

.article-item:hover{
  transform:translateX(6px);
  border-color:var(--line-strong);
  box-shadow:var(--shadow-md);
}

.article-item:hover::before{
  opacity:1;
  transform:scaleY(1);
}

.article-item h3{
  margin:0 0 8px;
  font-size:19px;
  line-height:1.5;
}

.article-item h3 a{
  color:var(--fg-strong);
}

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

.article-item .meta{
  margin-bottom:10px;
  font-size:13px;
  color:var(--muted);
}

.article-item .summary{
  margin-bottom:10px;
  color:var(--muted);
  font-size:15px;
}

.article-item > a:last-child{
  display:inline-block;
  font-size:14px;
  font-weight:700;
  color:var(--brand);
  transition:transform .3s var(--ease),color .3s var(--ease);
}

.article-item > a:last-child:hover{
  color:var(--brand-2);
  transform:translateX(4px);
}

/* ---------- FAQ ---------- */
.faq-list{
  display:grid;
  gap:12px;
}

.faq-item{
  border:1px solid var(--line);
  border-radius:var(--radius-sm);
  background:var(--card);
  -webkit-backdrop-filter:saturate(160%) blur(12px);
  backdrop-filter:saturate(160%) blur(12px);
  overflow:hidden;
  transition:border-color .3s var(--ease),box-shadow .3s var(--ease),background .3s var(--ease);
}

.faq-item:hover{
  border-color:var(--line-strong);
  box-shadow:var(--shadow-sm);
}

.faq-item.open{
  border-color:var(--line-strong);
  box-shadow:var(--shadow-md);
}

.faq-q{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  width:100%;
  padding:16px 20px;
  border:none;
  background:transparent;
  color:var(--fg-strong);
  font-size:16px;
  font-weight:700;
  font-family:inherit;
  text-align:left;
  cursor:pointer;
  transition:color .25s var(--ease),background .25s var(--ease);
}

.faq-q:hover{
  color:var(--brand);
  background:var(--brand-soft);
}

.faq-q span{
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  width:26px;
  height:26px;
  border-radius:50%;
  background:var(--brand-soft);
  color:var(--brand);
  font-size:17px;
  line-height:1;
  transition:transform .3s var(--ease),background .3s var(--ease),color .3s var(--ease);
}

.faq-item.open .faq-q span{
  transform:rotate(180deg);
  background:var(--grad-btn);
  color:#fff;
}

.faq-a{
  max-height:0;
  padding:0 20px;
  overflow:hidden;
  color:var(--muted);
  font-size:15px;
  transition:max-height .38s var(--ease),padding .38s var(--ease);
}

.faq-a p{
  margin:0;
  color:var(--muted);
}

.faq-item.open .faq-a{
  max-height:600px;
  padding:0 20px 18px;
}

/* ---------- Steps ---------- */
.steps{
  counter-reset:step;
  list-style:none;
  margin-top:8px;
}

.steps li{
  position:relative;
  padding-left:58px;
  margin-bottom:22px;
}

.steps li::before{
  counter-increment:step;
  content:counter(step);
  position:absolute;
  left:0;
  top:0;
  display:flex;
  align-items:center;
  justify-content:center;
  width:40px;
  height:40px;
  border-radius:50%;
  background:var(--grad-btn);
  color:#fff;
  font-weight:800;
  font-size:16px;
  box-shadow:0 8px 20px var(--brand-glow);
  transition:transform .35s var(--ease),box-shadow .35s var(--ease);
}

.steps li:hover::before{
  transform:scale(1.08);
  box-shadow:0 12px 28px var(--brand-glow);
}

.steps li::after{
  content:"";
  position:absolute;
  left:19px;
  top:44px;
  bottom:-18px;
  width:2px;
  background:linear-gradient(180deg,var(--line-strong),transparent);
}

.steps li:last-child::after{
  display:none;
}

.steps li h4{
  margin:0 0 6px;
  font-size:17px;
  color:var(--fg-strong);
}

.steps li p{
  margin:0;
  color:var(--muted);
  font-size:15px;
}

/* ---------- Blockquote ---------- */
blockquote.card{
  padding:24px 26px;
  border-left:4px solid transparent;
  border-image:linear-gradient(180deg,var(--brand),var(--brand-2)) 1;
  border-radius:var(--radius);
}

blockquote.card p{
  position:relative;
  padding-left:22px;
  color:var(--fg);
  font-style:normal;
}

blockquote.card p::before{
  content:"“";
  position:absolute;
  left:0;
  top:-6px;
  font-size:34px;
  line-height:1;
  color:var(--brand);
  opacity:.5;
  font-family:Georgia,serif;
}

blockquote.card footer{
  margin-top:10px;
  font-size:14px;
  color:var(--muted);
  text-align:right;
}

/* ---------- Tag ---------- */
.tag{
  display:inline-block;
  padding:3px 12px;
  margin:0 6px 6px 0;
  border-radius:var(--radius-pill);
  background:var(--brand-soft);
  color:var(--brand);
  font-size:13px;
  font-weight:600;
  transition:background .25s var(--ease),color .25s var(--ease),transform .25s var(--ease);
}

.tag:hover{
  background:var(--grad-btn);
  color:#fff;
  transform:translateY(-2px);
}

/* ---------- Contact ---------- */
.contact-info p{
  margin-bottom:10px;
  color:var(--fg);
}

.contact-info strong{
  color:var(--fg-strong);
}

.contact-info a{
  font-weight:600;
}

/* ---------- Footer ---------- */
footer.site-footer{
  padding:56px 0 26px;
  background:linear-gradient(180deg,var(--bg-alt),var(--bg));
  border-top:1px solid var(--line);
}

html[data-theme="dark"] footer.site-footer{
  background:linear-gradient(180deg,#0d1526,#0b1020);
}

.footer-grid{
  display:grid;
  grid-template-columns:2fr 1fr 1fr 1fr;
  gap:32px;
}

.footer-grid h4{
  margin:0 0 14px;
  font-size:16px;
  font-weight:800;
  color:var(--fg-strong);
  letter-spacing:.4px;
}

.footer-grid ul{
  list-style:none;
}

.footer-grid li{
  margin-bottom:9px;
}

.footer-grid a{
  color:var(--muted);
  font-size:14px;
  transition:color .25s var(--ease),padding-left .25s var(--ease);
}

.footer-grid a:hover{
  color:var(--brand);
  padding-left:4px;
}

.footer-bottom{
  display:flex;
  flex-wrap:wrap;
  justify-content:space-between;
  gap:10px;
  margin-top:34px;
  padding-top:20px;
  border-top:1px solid var(--line);
  font-size:13px;
  color:var(--muted);
}

/* ---------- Back to top ---------- */
.back-top{
  position:fixed;
  right:22px;
  bottom:26px;
  z-index:200;
  display:none;
  align-items:center;
  justify-content:center;
  width:48px;
  height:48px;
  border:none;
  border-radius:50%;
  background:var(--grad-btn);
  color:#fff;
  font-size:20px;
  cursor:pointer;
  box-shadow:0 12px 30px var(--brand-glow);
  transition:transform .3s var(--ease),box-shadow .3s var(--ease),filter .3s var(--ease);
}

.back-top:hover{
  transform:translateY(-4px) scale(1.06);
  box-shadow:0 18px 40px var(--brand-glow);
  filter:brightness(1.06);
}

.back-top:active{
  transform:translateY(-1px) scale(.98);
}

/* ---------- Reveal animation ---------- */
.reveal{
  opacity:0;
  transform:translateY(28px);
  transition:opacity .7s var(--ease),transform .7s var(--ease);
  will-change:opacity,transform;
}

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

/* ---------- Keyframes ---------- */
@keyframes shimmer{
  0%{background-position:0% 50%;}
  100%{background-position:200% 50%;}
}

@keyframes floatA{
  0%,100%{transform:translate3d(0,0,0) scale(1);}
  50%{transform:translate3d(40px,30px,0) scale(1.08);}
}

@keyframes floatB{
  0%,100%{transform:translate3d(0,0,0) scale(1);}
  50%{transform:translate3d(-36px,-28px,0) scale(1.1);}
}

/* ---------- Responsive ---------- */
@media (max-width:1024px){
  .grid-4{
    grid-template-columns:repeat(2,minmax(0,1fr));
  }
  .footer-grid{
    grid-template-columns:1.6fr 1fr 1fr;
  }
}

@media (max-width:900px){
  .grid-3,
  .grid-4{
    grid-template-columns:repeat(2,minmax(0,1fr));
  }
  .footer-grid{
    grid-template-columns:1fr 1fr;
  }
  .nav-wrap{
    gap:10px;
  }
  nav.main-nav ul{
    gap:2px;
  }
  nav.main-nav a{
    padding:8px 9px;
    font-size:14px;
  }
  .search-box input{
    width:100px;
  }
  section{
    padding:52px 0;
  }
}

@media (max-width:768px){
  .hero{
    padding:36px 0 56px;
  }
  .slide{
    padding:28px 24px;
  }
  .card{
    padding:20px;
  }
  .grid{
    gap:18px;
  }
}

@media (max-width:640px){
  :root{
    --header-h:60px;
  }
  body{
    font-size:15.5px;
  }
  .nav-wrap{
    padding:10px 16px;
  }
  .logo{
    font-size:18px;
  }
  .logo svg{
    width:34px;
    height:34px;
  }
  nav.main-nav{
    display:none;
  }
  nav.main-nav.open{
    display:block;
    position:absolute;
    top:100%;
    left:0;
    right:0;
    padding:14px 16px 18px;
    background:var(--glass);
    -webkit-backdrop-filter:saturate(180%) blur(20px);
    backdrop-filter:saturate(180%) blur(20px);
    border-bottom:1px solid var(--line);
    box-shadow:var(--shadow-md);
    animation:menuIn .3s var(--ease);
  }
  nav.main-nav.open ul{
    flex-direction:column;
    align-items:stretch;
    gap:4px;
  }
  nav.main-nav.open a{
    display:block;
    padding:10px 14px;
    font-size:15px;
    border-radius:var(--radius-sm);
  }
  nav.main-nav.open a::after{
    display:none;
  }
  .menu-toggle{
    display:inline-flex;
  }
  .search-box{
    display:none;
  }
  .grid-2,
  .grid-3,
  .grid-4{
    grid-template-columns:1fr;
  }
  .footer-grid{
    grid-template-columns:1fr;
    gap:24px;
  }
  .hero h1{
    font-size:25px;
  }
  .hero p{
    font-size:15.5px;
  }
  .hero-cta{
    gap:10px;
  }
  .btn{
    padding:11px 22px;
    font-size:14.5px;
  }
  section{
    padding:44px 0;
  }
  section h2{
    padding-left:14px;
  }
  section h2::before{
    width:5px;
  }
  .slide{
    padding:24px 20px;
  }
  .slide h3{
    font-size:18px;
  }
  .steps li{
    padding-left:50px;
  }
  .steps li::before{
    width:34px;
    height:34px;
    font-size:14px;
  }
  .steps li::after{
    left:16px;
    top:38px;
  }
  .article-item:hover{
    transform:none;
  }
  .back-top{
    right:16px;
    bottom:18px;
    width:44px;
    height:44px;
  }
  .footer-bottom{
    flex-direction:column;
    gap:6px;
  }
}

@media (max-width:400px){
  .container{
    padding:0 16px;
  }
  .hero h1{
    font-size:22px;
  }
  .card{
    padding:18px;
  }
  .btn{
    width:100%;
  }
}

@keyframes menuIn{
  from{
    opacity:0;
    transform:translateY(-10px);
  }
  to{
    opacity:1;
    transform:none;
  }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion:reduce){
  *,
  *::before,
  *::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  .reveal{
    opacity:1;
    transform:none;
  }
}

/* ---------- Print ---------- */
@media print{
  header.site-header,
  footer.site-footer,
  .back-top,
  .carousel,
  .hero-cta,
  .nav-tools{
    display:none !important;
  }
  body{
    background:#fff;
    color:#000;
  }
  .card,
  .stat,
  .article-item,
  .faq-item{
    background:#fff;
    box-shadow:none;
    border:1px solid #ddd;
  }
  .reveal{
    opacity:1;
    transform:none;
  }
}