:root {
  color-scheme: dark;
  --k-bg: #07111f;
  --k-bg-soft: #0b1728;
  --k-card: rgba(13, 28, 48, 0.88);
  --k-card-strong: #10233b;
  --k-line: rgba(148, 180, 214, 0.18);
  --k-text: #f4f8fc;
  --k-muted: #9fb1c6;
  --k-blue: #54a8ff;
  --k-cyan: #57e6d1;
  --k-orange: #ffbd66;
  --k-shadow: 0 24px 70px rgba(0, 0, 0, 0.28);
  --k-radius: 22px;
  --k-max: 1160px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    radial-gradient(circle at 10% 0%, rgba(52, 126, 255, 0.19), transparent 34rem),
    radial-gradient(circle at 90% 20%, rgba(40, 210, 185, 0.12), transparent 30rem),
    var(--k-bg);
  color: var(--k-text);
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }
img { max-width: 100%; }

.k-topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--k-line);
  background: rgba(7, 17, 31, 0.86);
  backdrop-filter: blur(18px);
}

.k-topbar-inner,
.k-shell {
  width: min(calc(100% - 40px), var(--k-max));
  margin: 0 auto;
}

.k-topbar-inner {
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.k-brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  font-weight: 760;
  letter-spacing: .01em;
}

.k-brand img { width: 34px; height: 34px; }
.k-brand small { display: block; color: var(--k-muted); font-size: 11px; font-weight: 560; }

.k-nav { display: flex; align-items: center; gap: 24px; }
.k-nav a { color: var(--k-muted); text-decoration: none; font-size: 14px; }
.k-nav a:hover { color: var(--k-text); }

.k-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  border: 1px solid rgba(96, 176, 255, .35);
  border-radius: 12px;
  background: rgba(64, 139, 232, .12);
  color: var(--k-text);
  text-decoration: none;
  font-weight: 720;
  transition: transform .18s ease, border-color .18s ease, background .18s ease;
}

.k-btn:hover { transform: translateY(-1px); border-color: var(--k-blue); }
.k-btn-primary {
  border-color: transparent;
  background: linear-gradient(135deg, #3289ff, #28c8b2);
  color: #04111d;
  box-shadow: 0 12px 32px rgba(43, 154, 225, .24);
}

.k-hero { padding: 86px 0 56px; }
.k-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 11px;
  border: 1px solid rgba(87, 230, 209, .25);
  border-radius: 999px;
  background: rgba(87, 230, 209, .08);
  color: var(--k-cyan);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .04em;
}
.k-eyebrow::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: currentColor; box-shadow: 0 0 14px currentColor; }

.k-hero h1,
.k-article-hero h1 {
  margin: 22px 0 18px;
  max-width: 920px;
  font-size: clamp(38px, 6vw, 72px);
  line-height: 1.08;
  letter-spacing: -.045em;
}

.k-gradient { color: transparent; background: linear-gradient(90deg, #82bfff, #73eedb); background-clip: text; -webkit-background-clip: text; }
.k-hero-lede { max-width: 780px; margin: 0; color: #bfd0e1; font-size: clamp(17px, 2vw, 21px); }
.k-hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 30px; }

.k-proof-strip {
  margin-top: 48px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  overflow: hidden;
  border: 1px solid var(--k-line);
  border-radius: 18px;
  background: rgba(9, 22, 38, .72);
}
.k-proof-strip div { padding: 22px 24px; border-right: 1px solid var(--k-line); }
.k-proof-strip div:last-child { border-right: 0; }
.k-proof-strip b { display: block; margin-bottom: 3px; font-size: 17px; }
.k-proof-strip span { color: var(--k-muted); font-size: 13px; }

.k-section { padding: 42px 0 76px; }
.k-section-head { display: flex; align-items: end; justify-content: space-between; gap: 24px; margin-bottom: 24px; }
.k-section-head h2 { margin: 0; font-size: clamp(27px, 4vw, 40px); letter-spacing: -.025em; }
.k-section-head p { max-width: 580px; margin: 0; color: var(--k-muted); }

.k-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.k-card {
  position: relative;
  min-height: 330px;
  padding: 30px;
  overflow: hidden;
  border: 1px solid var(--k-line);
  border-radius: var(--k-radius);
  background: linear-gradient(145deg, rgba(18, 39, 65, .93), rgba(9, 23, 40, .92));
  box-shadow: var(--k-shadow);
}
.k-card::after {
  content: "";
  position: absolute;
  width: 220px;
  height: 220px;
  top: -120px;
  right: -80px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(81, 169, 255, .2), transparent 68%);
}
.k-card-meta { display: flex; flex-wrap: wrap; gap: 8px; color: var(--k-muted); font-size: 12px; }
.k-tag { padding: 4px 9px; border-radius: 999px; background: rgba(84, 168, 255, .1); color: #a9d2ff; }
.k-card h3 { position: relative; z-index: 1; margin: 22px 0 12px; max-width: 580px; font-size: clamp(23px, 3vw, 32px); line-height: 1.25; letter-spacing: -.02em; }
.k-card p { position: relative; z-index: 1; margin: 0; color: var(--k-muted); }
.k-card-link { position: absolute; z-index: 2; left: 30px; bottom: 28px; color: var(--k-cyan); text-decoration: none; font-weight: 720; }
.k-card-link::after { content: " →"; }

.k-cta-band {
  display: grid;
  grid-template-columns: 1.3fr .7fr;
  align-items: center;
  gap: 28px;
  margin: 28px 0 78px;
  padding: 34px;
  border: 1px solid rgba(87, 230, 209, .2);
  border-radius: var(--k-radius);
  background: linear-gradient(120deg, rgba(37, 116, 213, .2), rgba(41, 202, 177, .12));
}
.k-cta-band h2 { margin: 0 0 8px; font-size: clamp(25px, 4vw, 38px); }
.k-cta-band p { margin: 0; color: var(--k-muted); }
.k-cta-actions { display: flex; justify-content: flex-end; }

.k-footer { border-top: 1px solid var(--k-line); background: rgba(4, 12, 22, .72); }
.k-footer-inner { padding: 34px 0; display: flex; justify-content: space-between; gap: 28px; color: var(--k-muted); font-size: 13px; }
.k-footer-links { display: flex; flex-wrap: wrap; gap: 16px; }
.k-footer a { text-decoration: none; }

/* Article */
.k-article-hero { padding: 70px 0 34px; }
.k-breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; color: var(--k-muted); font-size: 13px; }
.k-breadcrumbs a { text-decoration: none; }
.k-article-hero h1 { max-width: 980px; font-size: clamp(36px, 5.5vw, 64px); }
.k-article-deck { max-width: 820px; margin: 0; color: #bfd0e1; font-size: clamp(18px, 2vw, 22px); }
.k-article-meta { display: flex; flex-wrap: wrap; gap: 14px 24px; margin-top: 24px; color: var(--k-muted); font-size: 13px; }

.k-article-layout { display: grid; grid-template-columns: minmax(0, 760px) 260px; justify-content: space-between; gap: 64px; padding: 26px 0 80px; }
.k-article {
  min-width: 0;
  padding: 40px;
  border: 1px solid var(--k-line);
  border-radius: var(--k-radius);
  background: rgba(10, 23, 40, .82);
  box-shadow: var(--k-shadow);
}
.k-article h2 { margin: 48px 0 16px; font-size: clamp(25px, 3.5vw, 34px); line-height: 1.25; letter-spacing: -.02em; }
.k-article h2:first-child { margin-top: 0; }
.k-article h3 { margin: 32px 0 10px; font-size: 21px; }
.k-article p { margin: 0 0 18px; color: #d6e2ed; }
.k-article strong { color: #fff; }
.k-article ul,
.k-article ol { margin: 0 0 24px; padding-left: 1.25em; color: #d6e2ed; }
.k-article li { margin-bottom: 9px; }
.k-article a { color: #8bc4ff; }
.k-lead-box,
.k-note,
.k-comparison,
.k-checklist {
  margin: 26px 0;
  padding: 24px;
  border: 1px solid var(--k-line);
  border-radius: 16px;
  background: rgba(25, 48, 76, .58);
}
.k-lead-box { border-color: rgba(87, 230, 209, .28); background: rgba(33, 164, 145, .09); }
.k-lead-box p:last-child,
.k-note p:last-child { margin-bottom: 0; }
.k-quote { margin: 28px 0; padding: 3px 0 3px 22px; border-left: 3px solid var(--k-cyan); color: #f0fbf9; font-size: 20px; font-weight: 720; }
.k-comparison { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.k-comparison > div { padding: 18px; border-radius: 12px; background: rgba(7, 17, 31, .58); }
.k-comparison b { display: block; margin-bottom: 8px; }
.k-checklist { counter-reset: check; list-style: none; padding: 16px 24px; }
.k-checklist li { position: relative; padding: 14px 0 14px 42px; border-bottom: 1px solid var(--k-line); }
.k-checklist li:last-child { border-bottom: 0; }
.k-checklist li::before { counter-increment: check; content: counter(check); position: absolute; left: 0; top: 13px; width: 27px; height: 27px; border-radius: 8px; display: grid; place-items: center; background: rgba(84, 168, 255, .15); color: #9ed0ff; font-weight: 800; }

.k-inline-cta { margin: 42px 0 8px; padding: 30px; border-radius: 18px; background: linear-gradient(135deg, rgba(50, 137, 255, .2), rgba(40, 200, 178, .15)); border: 1px solid rgba(84, 168, 255, .25); }
.k-inline-cta h2 { margin: 0 0 8px; }
.k-inline-cta p { color: var(--k-muted); }

.k-aside { position: sticky; top: 94px; align-self: start; }
.k-aside-box { padding: 22px; border: 1px solid var(--k-line); border-radius: 16px; background: rgba(10, 23, 40, .75); }
.k-aside-box + .k-aside-box { margin-top: 16px; }
.k-aside h2 { margin: 0 0 14px; font-size: 15px; }
.k-aside a { display: block; padding: 7px 0; color: var(--k-muted); text-decoration: none; font-size: 13px; }
.k-aside a:hover { color: var(--k-text); }
.k-disclaimer { color: var(--k-muted); font-size: 13px; }

@media (max-width: 900px) {
  .k-nav > a:not(.k-btn) { display: none; }
  .k-proof-strip { grid-template-columns: 1fr; }
  .k-proof-strip div { border-right: 0; border-bottom: 1px solid var(--k-line); }
  .k-proof-strip div:last-child { border-bottom: 0; }
  .k-grid { grid-template-columns: 1fr; }
  .k-article-layout { grid-template-columns: 1fr; gap: 24px; }
  .k-aside { position: static; order: -1; }
  .k-aside-box:first-child { display: none; }
  .k-cta-band { grid-template-columns: 1fr; }
  .k-cta-actions { justify-content: flex-start; }
}

@media (max-width: 640px) {
  .k-topbar-inner,
  .k-shell { width: min(calc(100% - 28px), var(--k-max)); }
  .k-topbar-inner { min-height: 60px; }
  .k-brand small { display: none; }
  .k-nav .k-btn { min-height: 38px; padding: 0 13px; font-size: 13px; }
  .k-hero { padding: 58px 0 34px; }
  .k-hero h1,
  .k-article-hero h1 { letter-spacing: -.035em; }
  .k-card { min-height: 350px; padding: 24px; }
  .k-card-link { left: 24px; }
  .k-section-head { display: block; }
  .k-section-head p { margin-top: 10px; }
  .k-article { padding: 26px 20px; }
  .k-comparison { grid-template-columns: 1fr; }
  .k-footer-inner { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .k-btn { transition: none; }
}