/* ==========================================================================
   星空看台 · 共享样式 /assets/site.css
   深空底 · 玻璃浮岛 · 奶油档案 · 观测刻度
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

body,
h1, h2, h3, h4, h5,
p, figure, blockquote, dl, dd, ul, ol { margin: 0; }

ul, ol { padding-left: 0; }

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

button, input, select, textarea { font: inherit; color: inherit; }

a { color: inherit; }

table { border-collapse: collapse; }

:focus-visible {
  outline: 2px solid #FF8C42;
  outline-offset: 3px;
}

/* ---------- 2. Tokens ---------- */
:root {
  --xk-void: #0B1B3A;
  --xk-night: #131F45;
  --xk-indigo: #1C2A57;
  --xk-violet: #6C5CE7;
  --xk-violet-soft: rgba(108, 92, 231, .24);
  --xk-orange: #FF8C42;
  --xk-silver: #E8ECF1;
  --xk-cream: #F4E9D8;
  --xk-ink: #2B1D16;
  --xk-mist: #8B9BB4;
  --xk-teal: #7DE2D1;

  --xk-font-display: "HarmonyOS Sans SC", "PingFang SC", "Noto Sans SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --xk-font-body: "PingFang SC", "Noto Sans SC", "HarmonyOS Sans SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --xk-font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, "Liberation Mono", monospace;

  --xk-wrap: 1200px;
  --xk-gutter: clamp(18px, 4vw, 40px);
  --xk-radius-s: 10px;
  --xk-radius-m: 18px;
  --xk-radius-l: 28px;

  --xk-line: rgba(232, 236, 241, .14);
  --xk-line-strong: rgba(232, 236, 241, .3);
  --xk-ease: cubic-bezier(.22, .61, .36, 1);
  --xk-shadow-float: 0 24px 50px -34px rgba(0, 0, 0, .95);
}

/* ---------- 3. Base ---------- */
body {
  min-height: 100vh;
  min-height: 100dvh;
  font-family: var(--xk-font-body);
  font-size: 17px;
  line-height: 1.75;
  color: var(--xk-silver);
  background-color: var(--xk-void);
  background-image:
    radial-gradient(1200px 780px at 84% -14%, rgba(108, 92, 231, .30), transparent 64%),
    radial-gradient(880px 620px at 2% 4%, rgba(255, 140, 66, .10), transparent 62%),
    radial-gradient(1000px 720px at 50% 116%, rgba(28, 42, 87, .88), transparent 72%),
    radial-gradient(1.4px 1.4px at 12% 16%, rgba(232, 236, 241, .7), transparent 100%),
    radial-gradient(1.2px 1.2px at 78% 9%, rgba(232, 236, 241, .55), transparent 100%),
    radial-gradient(1px 1px at 34% 46%, rgba(232, 236, 241, .4), transparent 100%),
    radial-gradient(1.6px 1.6px at 92% 58%, rgba(232, 236, 241, .45), transparent 100%),
    radial-gradient(1px 1px at 58% 82%, rgba(232, 236, 241, .34), transparent 100%);
  background-repeat: no-repeat;
  background-color: var(--xk-void);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  font-family: var(--xk-font-display);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -.012em;
  color: inherit;
}

p { text-wrap: pretty; }

::selection {
  background: rgba(108, 92, 231, .55);
  color: #FFFFFF;
}

/* ---------- 4. Layout primitives ---------- */
.xk-container {
  width: min(var(--xk-wrap), calc(100% - var(--xk-gutter) * 2));
  margin-inline: auto;
}

.xk-section { padding-block: clamp(44px, 6vw, 88px); }
.xk-section--tight { padding-block: clamp(24px, 3.4vw, 48px); }

/* ---------- 5. Typography helpers ---------- */
.xk-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--xk-font-mono);
  font-size: .68rem;
  font-weight: 500;
  letter-spacing: .28em;
  text-transform: uppercase;
  color: var(--xk-mist);
}

.xk-eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  flex: 0 0 auto;
  background: linear-gradient(90deg, var(--xk-orange), rgba(255, 140, 66, 0));
}

.xk-h1 {
  font-size: clamp(2.35rem, 5.4vw, 4rem);
  font-weight: 900;
  letter-spacing: -.02em;
}

.xk-h2 { font-size: clamp(1.55rem, 2.9vw, 2.25rem); }
.xk-h3 { font-size: clamp(1.1rem, 1.7vw, 1.35rem); }

.xk-lede {
  max-width: 62ch;
  font-size: clamp(1rem, 1.5vw, 1.15rem);
  line-height: 1.85;
  color: rgba(232, 236, 241, .82);
}

.xk-mono {
  font-family: var(--xk-font-mono);
  font-size: .78rem;
  letter-spacing: .08em;
  color: var(--xk-mist);
}

/* ---------- 6. Skip link ---------- */
.xk-skip {
  position: fixed;
  top: 12px;
  left: 50%;
  z-index: 200;
  padding: 11px 22px;
  border-radius: 999px;
  background: var(--xk-orange);
  color: var(--xk-ink);
  font-family: var(--xk-font-display);
  font-size: .88rem;
  font-weight: 800;
  text-decoration: none;
  box-shadow: 0 16px 34px -18px rgba(0, 0, 0, .9);
  transform: translate(-50%, -180%);
  transition: transform .26s var(--xk-ease);
}

.xk-skip:focus,
.xk-skip:focus-visible { transform: translate(-50%, 0); }

/* ---------- 7. Header · 悬浮胶囊浮岛 ---------- */
.xk-header {
  position: sticky;
  top: 0;
  z-index: 90;
  padding: 14px clamp(12px, 3vw, 28px) 6px;
  background: linear-gradient(180deg, rgba(11, 27, 58, .92) 0%, rgba(11, 27, 58, .55) 62%, rgba(11, 27, 58, 0) 100%);
}

.xk-header__inner {
  width: min(var(--xk-wrap), 100%);
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: clamp(10px, 1.6vw, 22px);
  padding: 10px 12px 10px 18px;
  border-radius: 999px;
  border: 1px solid var(--xk-line);
  background: rgba(19, 31, 69, .74);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
  backdrop-filter: blur(16px) saturate(140%);
  box-shadow:
    0 22px 46px -34px rgba(0, 0, 0, .95),
    inset 0 1px 0 rgba(232, 236, 241, .09);
  transition: background-color .3s var(--xk-ease), box-shadow .3s var(--xk-ease);
}

.xk-header.is-scrolled .xk-header__inner {
  background: rgba(19, 31, 69, .92);
  box-shadow:
    0 26px 50px -32px rgba(0, 0, 0, 1),
    inset 0 1px 0 rgba(232, 236, 241, .12);
}

/* 品牌 */
.xk-brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  flex: 0 0 auto;
  padding: 4px 6px 4px 0;
  border-radius: 999px;
  text-decoration: none;
  color: var(--xk-silver);
}

.xk-brand__mark {
  position: relative;
  width: 28px;
  height: 28px;
  flex: 0 0 auto;
  display: grid;
  place-items: center;
  border-radius: 50%;
  border: 1px solid rgba(232, 236, 241, .32);
  background: radial-gradient(circle at 32% 26%, rgba(108, 92, 231, .92), rgba(28, 42, 87, .95));
}

.xk-brand__mark::before {
  content: "";
  position: absolute;
  inset: -6px;
  border-radius: 50%;
  border: 1px solid rgba(108, 92, 231, .5);
  border-right-color: transparent;
  border-bottom-color: transparent;
  transform: rotate(-26deg);
}

.xk-brand__mark::after {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--xk-orange);
  box-shadow: 0 0 0 3px rgba(255, 140, 66, .2);
}

.xk-brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.xk-brand__name {
  font-family: var(--xk-font-display);
  font-size: 1.02rem;
  font-weight: 900;
  letter-spacing: .04em;
}

.xk-brand__line {
  font-family: var(--xk-font-mono);
  font-size: .58rem;
  letter-spacing: .26em;
  text-transform: uppercase;
  color: var(--xk-mist);
}

/* 导航 */
.xk-nav {
  flex: 1 1 auto;
  display: flex;
  justify-content: center;
  min-width: 0;
}

.xk-nav__list {
  display: flex;
  align-items: center;
  gap: 2px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.xk-nav__item { display: flex; }

.xk-nav__link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 8px 13px;
  border-radius: 999px;
  font-size: .86rem;
  font-weight: 500;
  letter-spacing: .01em;
  white-space: nowrap;
  text-decoration: none;
  color: rgba(232, 236, 241, .78);
  transition: color .24s var(--xk-ease), background-color .24s var(--xk-ease), box-shadow .24s var(--xk-ease);
}

.xk-nav__link:hover {
  color: var(--xk-silver);
  background: rgba(108, 92, 231, .18);
}

.xk-nav__link[aria-current="page"] {
  color: var(--xk-silver);
  background: rgba(108, 92, 231, .3);
  box-shadow: inset 0 0 0 1px rgba(108, 92, 231, .6);
}

.xk-nav__link[aria-current="page"]::before {
  content: "";
  width: 5px;
  height: 5px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--xk-orange);
  box-shadow: 0 0 0 3px rgba(255, 140, 66, .18);
}

/* 头部行动 */
.xk-header__actions {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
}

.xk-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 18px;
  border-radius: 999px;
  background: var(--xk-orange);
  color: var(--xk-ink);
  font-family: var(--xk-font-display);
  font-size: .82rem;
  font-weight: 800;
  letter-spacing: .02em;
  text-decoration: none;
  box-shadow: 0 14px 30px -18px rgba(255, 140, 66, .95);
  transition: transform .24s var(--xk-ease), background-color .24s var(--xk-ease), box-shadow .24s var(--xk-ease);
}

.xk-cta:hover {
  background: #FF9E5E;
  transform: translateY(-2px);
  box-shadow: 0 18px 34px -16px rgba(255, 140, 66, .95);
}

/* 移动端按钮 */
.xk-nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 15px;
  border-radius: 999px;
  border: 1px solid var(--xk-line-strong);
  background: rgba(28, 42, 87, .8);
  color: var(--xk-silver);
  font-family: var(--xk-font-display);
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .06em;
  cursor: pointer;
  transition: border-color .24s var(--xk-ease), background-color .24s var(--xk-ease);
}

.xk-nav-toggle:hover { border-color: rgba(108, 92, 231, .8); }

.xk-nav-toggle__bars {
  position: relative;
  width: 16px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: background-color .28s var(--xk-ease);
}

.xk-nav-toggle__bars::before,
.xk-nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform .28s var(--xk-ease), top .28s var(--xk-ease);
}

.xk-nav-toggle__bars::before { top: -5px; }
.xk-nav-toggle__bars::after { top: 5px; }

.xk-header[data-open="true"] .xk-nav-toggle__bars { background: transparent; }
.xk-header[data-open="true"] .xk-nav-toggle__bars::before { top: 0; transform: rotate(45deg); }
.xk-header[data-open="true"] .xk-nav-toggle__bars::after { top: 0; transform: rotate(-45deg); }

/* ---------- 8. Buttons ---------- */
.xk-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .55em;
  padding: .8em 1.6em;
  border: 1px solid transparent;
  border-radius: 999px;
  font-family: var(--xk-font-display);
  font-size: .9rem;
  font-weight: 800;
  letter-spacing: .02em;
  text-decoration: none;
  cursor: pointer;
  transition: transform .26s var(--xk-ease), background-color .26s var(--xk-ease), border-color .26s var(--xk-ease), box-shadow .26s var(--xk-ease);
}

.xk-btn--primary {
  background: var(--xk-orange);
  color: var(--xk-ink);
  box-shadow: 0 16px 34px -22px rgba(255, 140, 66, 1);
}

.xk-btn--primary:hover {
  background: #FF9E5E;
  transform: translateY(-2px);
}

.xk-btn--violet {
  background: var(--xk-violet);
  color: #FFFFFF;
  box-shadow: 0 16px 34px -22px rgba(108, 92, 231, 1);
}

.xk-btn--violet:hover {
  background: #7E6FF0;
  transform: translateY(-2px);
}

.xk-btn--ghost {
  background: rgba(28, 42, 87, .45);
  border-color: var(--xk-line-strong);
  color: var(--xk-silver);
}

.xk-btn--ghost:hover {
  border-color: rgba(108, 92, 231, .8);
  background: rgba(108, 92, 231, .2);
  transform: translateY(-2px);
}

/* ---------- 9. Breadcrumbs ---------- */
.xk-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--xk-font-mono);
  font-size: .72rem;
  letter-spacing: .08em;
  color: var(--xk-mist);
}

.xk-crumbs__item {
  display: inline-flex;
  align-items: center;
}

.xk-crumbs__item + .xk-crumbs__item::before {
  content: "/";
  margin: 0 .6em;
  color: rgba(139, 155, 180, .55);
}

.xk-crumbs a {
  text-decoration: none;
  color: var(--xk-mist);
  transition: color .24s var(--xk-ease);
}

.xk-crumbs a:hover { color: var(--xk-silver); }

.xk-crumbs [aria-current="page"] { color: var(--xk-silver); }

/* ---------- 10. Grid ---------- */
.xk-grid {
  display: grid;
  gap: clamp(16px, 2.4vw, 28px);
}

.xk-grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.xk-grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.xk-grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* ---------- 11. Cards ---------- */
.xk-card {
  position: relative;
  border-radius: var(--xk-radius-m);
  border: 1px solid var(--xk-line);
  padding: clamp(20px, 3vw, 30px);
  transition: transform .32s var(--xk-ease), border-color .32s var(--xk-ease), box-shadow .32s var(--xk-ease);
}

.xk-card--glass {
  background:
    linear-gradient(160deg, rgba(28, 42, 87, .66), rgba(11, 27, 58, .5));
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  box-shadow:
    var(--xk-shadow-float),
    inset 0 1px 0 rgba(232, 236, 241, .08);
}

.xk-card--glass:hover {
  transform: translateY(-4px);
  border-color: rgba(108, 92, 231, .6);
}

.xk-card--paper {
  background: var(--xk-cream);
  color: var(--xk-ink);
  border-color: rgba(43, 29, 22, .18);
  box-shadow: 0 22px 44px -34px rgba(0, 0, 0, .95);
}

.xk-card--paper h1,
.xk-card--paper h2,
.xk-card--paper h3,
.xk-card--paper h4 { color: var(--xk-ink); }

.xk-card--paper .xk-mono { color: rgba(43, 29, 22, .68); }

.xk-card--paper .xk-eyebrow { color: rgba(43, 29, 22, .62); }

/* ---------- 12. Media containers ---------- */
.xk-media {
  position: relative;
  overflow: hidden;
  border-radius: var(--xk-radius-m);
  border: 1px solid var(--xk-line);
  background:
    radial-gradient(120% 90% at 78% 12%, rgba(108, 92, 231, .38), transparent 62%),
    linear-gradient(150deg, var(--xk-indigo), var(--xk-night) 70%, var(--xk-void));
}

.xk-media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    repeating-linear-gradient(90deg, rgba(232, 236, 241, .12) 0 1px, transparent 1px 40px),
    repeating-linear-gradient(0deg, rgba(232, 236, 241, .08) 0 1px, transparent 1px 40px);
  opacity: .35;
}

.xk-media > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  position: relative;
  z-index: 1;
}

.xk-media--wide { aspect-ratio: 16 / 9; }
.xk-media--tall { aspect-ratio: 3 / 4; }
.xk-media--square { aspect-ratio: 1 / 1; }

.xk-media__caption {
  position: absolute;
  inset: auto 0 0 0;
  z-index: 2;
  padding: 26px 16px 14px;
  font-family: var(--xk-font-mono);
  font-size: .68rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: rgba(232, 236, 241, .9);
  background: linear-gradient(180deg, rgba(11, 27, 58, 0), rgba(11, 27, 58, .88));
}

/* ---------- 13. Chips & status ---------- */
.xk-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: 999px;
  border: 1px solid var(--xk-line-strong);
  font-family: var(--xk-font-mono);
  font-size: .68rem;
  letter-spacing: .1em;
  color: var(--xk-mist);
  background: rgba(28, 42, 87, .4);
}

.xk-chip--violet {
  color: #CFC8FF;
  border-color: rgba(108, 92, 231, .7);
  background: rgba(108, 92, 231, .2);
}

.xk-chip--orange {
  color: #FFD3B4;
  border-color: rgba(255, 140, 66, .7);
  background: rgba(255, 140, 66, .16);
}

.xk-chip--teal {
  color: #B6F3E9;
  border-color: rgba(125, 226, 209, .6);
  background: rgba(125, 226, 209, .14);
}

.xk-dot {
  display: inline-block;
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--xk-orange);
  box-shadow: 0 0 0 4px rgba(255, 140, 66, .18);
  vertical-align: middle;
}

/* ---------- 14. Prose ---------- */
.xk-prose {
  max-width: 72ch;
  font-size: 1.02rem;
  line-height: 1.9;
  color: rgba(232, 236, 241, .86);
}

.xk-prose > * + * { margin-top: 1.15em; }

.xk-prose h2 {
  margin-top: 1.9em;
  font-size: clamp(1.3rem, 2.2vw, 1.7rem);
}

.xk-prose h3 {
  margin-top: 1.6em;
  font-size: 1.14rem;
}

.xk-prose ul,
.xk-prose ol {
  padding-left: 1.4em;
}

.xk-prose li + li { margin-top: .5em; }

.xk-prose a {
  color: var(--xk-orange);
  text-underline-offset: 3px;
}

.xk-prose strong { color: var(--xk-silver); }

.xk-card--paper .xk-prose { color: var(--xk-ink); }
.xk-card--paper .xk-prose strong { color: var(--xk-ink); }
.xk-card--paper .xk-prose a { color: #B85A15; }

/* ---------- 15. Footer ---------- */
.xk-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 110px);
  border-top: 1px solid var(--xk-line);
  background:
    radial-gradient(760px 340px at 86% 0%, rgba(108, 92, 231, .24), transparent 70%),
    linear-gradient(180deg, rgba(19, 31, 69, .58), rgba(11, 27, 58, .98) 56%);
  color: var(--xk-silver);
}

.xk-footer::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 1px;
  background: repeating-linear-gradient(90deg, rgba(232, 236, 241, .42) 0 1px, transparent 1px 16px);
  opacity: .45;
  pointer-events: none;
}

.xk-footer__inner {
  width: min(var(--xk-wrap), calc(100% - var(--xk-gutter) * 2));
  margin-inline: auto;
  padding-block: clamp(40px, 5vw, 68px) clamp(18px, 3vw, 30px);
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(0, 1.5fr) minmax(0, 1.2fr);
  gap: clamp(28px, 4vw, 56px);
  align-items: start;
}

.xk-footer__logo {
  font-family: var(--xk-font-display);
  font-size: 1.5rem;
  font-weight: 900;
  letter-spacing: .04em;
}

.xk-footer__logo::after {
  content: "·";
  margin-left: .28em;
  color: var(--xk-orange);
}

.xk-footer__summary {
  max-width: 30ch;
  margin-top: 12px;
  font-size: .9rem;
  line-height: 1.8;
  color: var(--xk-mist);
}

.xk-footer__status {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-top: 18px;
  font-family: var(--xk-font-mono);
  font-size: .68rem;
  letter-spacing: .14em;
  color: rgba(232, 236, 241, .72);
}

.xk-footer__cols {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 36px);
}

.xk-footer__col-title {
  margin-bottom: 16px;
  font-family: var(--xk-font-mono);
  font-size: .68rem;
  font-weight: 500;
  letter-spacing: .26em;
  text-transform: uppercase;
  color: rgba(139, 155, 180, .95);
}

.xk-footer__list {
  display: grid;
  gap: 11px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: .9rem;
}

.xk-footer__list a {
  display: inline-block;
  text-decoration: none;
  color: rgba(232, 236, 241, .82);
  transition: color .24s var(--xk-ease), transform .24s var(--xk-ease);
}

.xk-footer__list a:hover {
  color: var(--xk-orange);
  transform: translateX(3px);
}

.xk-footer__list--plain li {
  display: grid;
  gap: 3px;
}

.xk-footer__label {
  font-family: var(--xk-font-mono);
  font-size: .62rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: rgba(139, 155, 180, .9);
}

.xk-footer__value {
  font-size: .88rem;
  line-height: 1.7;
  color: rgba(232, 236, 241, .88);
  overflow-wrap: anywhere;
}

.xk-footer__bottom {
  width: min(var(--xk-wrap), calc(100% - var(--xk-gutter) * 2));
  margin-inline: auto;
  padding-block: 18px 28px;
  border-top: 1px solid var(--xk-line);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 26px;
  font-family: var(--xk-font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--xk-mist);
}

.xk-footer__legal { color: rgba(139, 155, 180, .9); }

/* ---------- 16. Scroll progress & back to top ---------- */
.xk-progress {
  position: fixed;
  inset: 0 0 auto 0;
  height: 3px;
  z-index: 120;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--xk-violet), var(--xk-orange));
  pointer-events: none;
  transition: transform .12s linear;
}

.xk-totop {
  position: fixed;
  right: clamp(14px, 2.4vw, 30px);
  bottom: clamp(14px, 2.4vw, 30px);
  z-index: 110;
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  padding: 0;
  border-radius: 50%;
  border: 1px solid var(--xk-line-strong);
  background: rgba(19, 31, 69, .88);
  color: var(--xk-silver);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  box-shadow: 0 18px 34px -24px rgba(0, 0, 0, 1);
  transition: opacity .3s var(--xk-ease), transform .3s var(--xk-ease), visibility .3s, border-color .3s var(--xk-ease), background-color .3s var(--xk-ease);
}

.xk-totop.is-on {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.xk-totop:hover {
  border-color: rgba(255, 140, 66, .9);
  background: rgba(28, 42, 87, .95);
}

.xk-totop__arrow {
  width: 10px;
  height: 10px;
  border-left: 2px solid currentColor;
  border-top: 2px solid currentColor;
  transform: rotate(45deg) translate(1px, 1px);
}

/* ---------- 17. Reveal ---------- */
html.xk-animify .xk-reveal {
  opacity: 0;
  transform: translateY(18px);
}

html.xk-animify .xk-reveal.is-visible {
  opacity: 1;
  transform: none;
  transition: opacity .62s var(--xk-ease), transform .62s var(--xk-ease);
}

/* ---------- 18. Responsive ---------- */
@media (max-width: 1180px) {
  .xk-nav__link { padding: 8px 10px; font-size: .84rem; }
}

@media (max-width: 1024px) {
  .xk-header { padding: 10px clamp(10px, 3vw, 20px) 4px; }

  .xk-header__inner {
    flex-wrap: wrap;
    border-radius: 26px;
    padding: 10px 12px;
    gap: 10px;
  }

  .xk-brand { margin-right: auto; }

  .xk-nav-toggle {
    display: inline-flex;
    order: 3;
  }

  .xk-header__actions {
    order: 2;
    margin-left: auto;
  }

  .xk-cta { padding: 8px 14px; font-size: .78rem; }

  .xk-nav {
    order: 4;
    flex: 1 0 100%;
    width: 100%;
    display: none;
    justify-content: flex-start;
    margin: 0;
    padding-top: 8px;
    border-top: 1px solid var(--xk-line);
  }

  .xk-header[data-open="true"] .xk-nav { display: block; }

  .xk-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    width: 100%;
    padding: 6px 0 6px;
  }

  .xk-nav__link {
    display: flex;
    width: 100%;
    padding: 13px 16px;
    border-radius: 14px;
    font-size: .95rem;
  }

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

  .xk-footer__brand { grid-column: 1 / -1; }
}

@media (max-width: 900px) {
  .xk-grid--3,
  .xk-grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 720px) {
  body { font-size: 16px; }

  .xk-footer__inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 32px;
  }

  .xk-footer__summary { max-width: 46ch; }
}

@media (max-width: 620px) {
  .xk-grid--2,
  .xk-grid--3,
  .xk-grid--4 { grid-template-columns: minmax(0, 1fr); }

  .xk-header__actions { display: none; }

  .xk-brand__line { letter-spacing: .2em; }

  .xk-footer__bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .xk-btn { width: 100%; }
}

@media (max-width: 380px) {
  .xk-nav-toggle__label { display: none; }
}

/* ---------- 19. Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
    scroll-behavior: auto !important;
  }

  html.xk-animify .xk-reveal {
    opacity: 1;
    transform: none;
  }

  .xk-totop,
  .xk-progress { transition: none; }
}