/* ==========================================================================
   K体育主站 · 共享样式表 /assets/site.css
   夜场竞技底色 + 荧光青绿 / 信号橙强调
   ========================================================================== */

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

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

body,
h1, h2, h3, h4, h5, h6,
p, ul, ol, li, figure, figcaption, blockquote, dl, dd, fieldset { margin: 0; }

ul, ol { padding: 0; list-style: none; }

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

a { color: inherit; text-decoration: none; }

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

table { border-collapse: collapse; width: 100%; }

:focus-visible {
  outline: 2px solid var(--k-neon);
  outline-offset: 3px;
  border-radius: 3px;
}

::selection { background: rgba(43, 227, 176, 0.3); color: #ffffff; }

/* --- 2. 设计变量 --------------------------------------------------------- */
:root {
  /* 色板 */
  --k-bg: #0B0F14;
  --k-panel: #141A22;
  --k-white: #E8F1F5;
  --k-neon: #2BE3B0;
  --k-signal: #FF7A29;
  --k-violet: #6C7CFF;
  --k-muted: #7A8A99;
  --k-teal-deep: #0E3B33;
  --k-coral: #FF5A5F;
  --k-ink: #0B0F14;
  --k-line: rgba(31, 42, 54, 0.78);
  --k-line-soft: rgba(31, 42, 54, 0.46);
  --k-grid-line: rgba(31, 42, 54, 0.55);
  --k-shadow: 0 24px 60px -32px rgba(0, 0, 0, 0.92);

  /* 字体 */
  --k-font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", "Noto Sans SC", sans-serif;
  --k-font-mono: ui-monospace, "SF Mono", "JetBrains Mono", "IBM Plex Mono",
    Menlo, Consolas, "Liberation Mono", monospace;

  /* 字号阶梯 */
  --k-fs-xs: 12px;
  --k-fs-sm: 14px;
  --k-fs-base: 16px;
  --k-fs-md: 20px;
  --k-fs-lg: 28px;
  --k-fs-xl: 40px;
  --k-fs-2xl: clamp(44px, 5.4vw, 64px);
  --k-fs-3xl: clamp(52px, 8vw, 88px);

  /* 空间与容器 */
  --k-shell: 1320px;
  --k-gutter: clamp(18px, 4vw, 40px);
  --k-gap-sm: 24px;
  --k-gap-md: 40px;
  --k-gap-lg: 72px;

  /* 不等半径，制造手工轮廓 */
  --k-r-1: 2px;
  --k-r-2: 8px;
  --k-r-3: 14px;
  --k-r-4: 18px;

  --k-ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* --- 3. 中文排版与页面底色 ------------------------------------------------ */
body {
  min-height: 100vh;
  background-color: var(--k-bg);
  background-image:
    repeating-linear-gradient(90deg, var(--k-grid-line) 0 1px, transparent 1px 96px),
    radial-gradient(1200px 520px at 82% -12%, rgba(43, 227, 176, 0.09), transparent 68%),
    radial-gradient(900px 420px at 4% 8%, rgba(108, 124, 255, 0.08), transparent 70%);
  background-attachment: fixed;
  color: var(--k-white);
  font-family: var(--k-font-sans);
  font-size: var(--k-fs-base);
  font-weight: 400;
  line-height: 1.75;
  letter-spacing: 0.005em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h1 { font-size: var(--k-fs-3xl); }
h2 { font-size: var(--k-fs-2xl); }
h3 { font-size: var(--k-fs-lg); }
h4 { font-size: var(--k-fs-md); font-weight: 700; }

#main-content { scroll-margin-top: 92px; }

/* --- 4. 容器与网格 ------------------------------------------------------- */
.k-shell {
  width: 100%;
  max-width: var(--k-shell);
  margin: 0 auto;
  padding-left: var(--k-gutter);
  padding-right: var(--k-gutter);
}

.k-grid { display: grid; gap: var(--k-gap-sm); }
.k-grid--12 { grid-template-columns: repeat(12, minmax(0, 1fr)); }
.k-grid--2 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.k-grid--3 { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.k-grid--4 { grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); }

.k-span-1 { grid-column: span 1; }
.k-span-2 { grid-column: span 2; }
.k-span-3 { grid-column: span 3; }
.k-span-4 { grid-column: span 4; }
.k-span-5 { grid-column: span 5; }
.k-span-6 { grid-column: span 6; }
.k-span-7 { grid-column: span 7; }
.k-span-8 { grid-column: span 8; }
.k-span-9 { grid-column: span 9; }
.k-span-10 { grid-column: span 10; }
.k-span-11 { grid-column: span 11; }
.k-span-12 { grid-column: span 12; }

/* --- 5. 通用文字工具 ----------------------------------------------------- */
.k-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--k-neon);
}

.k-eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: currentColor;
}

.k-num {
  font-family: var(--k-font-mono);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
  line-height: 1.2;
}

.k-vlabel {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--k-muted);
}

.k-rule {
  height: 1px;
  border: 0;
  background: var(--k-line);
}

.k-prose {
  max-width: 66ch;
  color: rgba(232, 241, 245, 0.86);
  line-height: 1.75;
}

.k-prose > * + * { margin-top: 1.15em; }
.k-prose h2 { font-size: var(--k-fs-lg); margin-top: 1.6em; }
.k-prose h3 { font-size: var(--k-fs-md); margin-top: 1.4em; }
.k-prose strong { color: var(--k-white); font-weight: 700; }
.k-prose a { color: var(--k-neon); border-bottom: 1px solid rgba(43, 227, 176, 0.4); }
.k-prose code {
  font-family: var(--k-font-mono);
  font-size: 0.92em;
  padding: 2px 6px;
  border-radius: var(--k-r-1) var(--k-r-2) var(--k-r-1) var(--k-r-2);
  background: var(--k-panel);
  color: var(--k-neon);
}

.k-aside {
  padding-left: 16px;
  border-left: 1px solid var(--k-line);
  font-size: 13px;
  line-height: 1.8;
  color: var(--k-muted);
  max-width: 30ch;
}

/* --- 6. 章节 ------------------------------------------------------------- */
.k-section {
  position: relative;
  padding-top: var(--k-gap-lg);
  padding-bottom: var(--k-gap-lg);
}

.k-section__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px 24px;
  margin-bottom: var(--k-gap-md);
}

.k-section__title {
  font-size: var(--k-fs-lg);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.15;
}

/* --- 7. 按钮与标签 ------------------------------------------------------- */
.k-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border: 1px solid transparent;
  border-radius: var(--k-r-3) var(--k-r-1) var(--k-r-3) var(--k-r-1);
  font-size: var(--k-fs-sm);
  font-weight: 700;
  letter-spacing: 0.02em;
  white-space: nowrap;
  transition: background-color 0.22s var(--k-ease), color 0.22s var(--k-ease),
    border-color 0.22s var(--k-ease), transform 0.22s var(--k-ease);
}

.k-btn:hover { transform: translateY(-1px); }
.k-btn:active { transform: translateY(0); }

.k-btn--signal {
  background: var(--k-signal);
  color: #1B0B02;
  box-shadow: 0 12px 30px -18px rgba(255, 122, 41, 0.9);
}

.k-btn--signal:hover { background: #FF8F4A; }

.k-btn--neon {
  background: var(--k-neon);
  color: #04231B;
}

.k-btn--neon:hover { background: #56EBC0; }

.k-btn--ghost {
  background: transparent;
  border-color: var(--k-line);
  color: var(--k-white);
}

.k-btn--ghost:hover {
  border-color: rgba(43, 227, 176, 0.55);
  color: var(--k-neon);
  background: rgba(43, 227, 176, 0.07);
}

.k-btn--sm {
  padding: 8px 15px;
  font-size: 13px;
}

.k-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border: 1px solid var(--k-line);
  border-radius: var(--k-r-2) var(--k-r-1) var(--k-r-2) var(--k-r-1);
  background: rgba(20, 26, 34, 0.82);
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.08em;
  color: var(--k-muted);
  white-space: nowrap;
}

.k-tag--neon {
  color: var(--k-neon);
  border-color: rgba(43, 227, 176, 0.36);
  background: var(--k-teal-deep);
}

.k-tag--signal {
  color: var(--k-signal);
  border-color: rgba(255, 122, 41, 0.36);
  background: rgba(255, 122, 41, 0.09);
}

.k-tag--violet {
  color: var(--k-violet);
  border-color: rgba(108, 124, 255, 0.34);
  background: rgba(108, 124, 255, 0.09);
}

.k-tag--coral {
  color: var(--k-coral);
  border-color: rgba(255, 90, 95, 0.34);
  background: rgba(255, 90, 95, 0.09);
}

/* --- 8. 卡片、图片容器、刻度 --------------------------------------------- */
.k-card {
  position: relative;
  padding: 24px;
  background: var(--k-panel);
  border: 1px solid var(--k-line);
  border-radius: var(--k-r-3) var(--k-r-1) var(--k-r-3) var(--k-r-1);
  transition: border-color 0.25s var(--k-ease), transform 0.25s var(--k-ease);
}

.k-card:hover { border-color: rgba(43, 227, 176, 0.42); }

.k-media {
  position: relative;
  display: block;
  overflow: hidden;
  width: 100%;
  background: var(--k-panel);
  border: 1px solid var(--k-line);
  border-radius: var(--k-r-4) var(--k-r-1) var(--k-r-4) var(--k-r-1);
}

.k-media__img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.92) contrast(1.04);
}

.k-media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(118deg, rgba(43, 227, 176, 0.12), rgba(11, 15, 20, 0) 46%),
    repeating-linear-gradient(0deg, rgba(31, 42, 54, 0.5) 0 1px, transparent 1px 42px);
}

.k-media__cap {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1;
  padding: 14px 16px;
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.08em;
  color: var(--k-white);
  background: linear-gradient(180deg, rgba(11, 15, 20, 0), rgba(11, 15, 20, 0.88));
}

.k-media--wide { aspect-ratio: 16 / 9; }
.k-media--frame { aspect-ratio: 4 / 3; }
.k-media--portrait { aspect-ratio: 3 / 4; }
.k-media--square { aspect-ratio: 1 / 1; }

.k-ticks {
  display: flex;
  align-items: flex-end;
  gap: 6px;
  height: 14px;
  margin-top: 20px;
}

.k-ticks span {
  display: block;
  width: 1px;
  height: 7px;
  background: var(--k-line);
}

.k-ticks span:nth-child(3n) {
  height: 14px;
  background: rgba(43, 227, 176, 0.55);
}

/* --- 9. 面包屑 ----------------------------------------------------------- */
.k-breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.1em;
  color: var(--k-muted);
}

.k-breadcrumb li { display: flex; align-items: center; gap: 8px; }

.k-breadcrumb li + li::before {
  content: "/";
  color: rgba(31, 42, 54, 0.95);
}

.k-breadcrumb a { transition: color 0.2s var(--k-ease); }
.k-breadcrumb a:hover { color: var(--k-neon); }

/* --- 10. 章节高亮链接 ----------------------------------------------------- */
.k-spylink {
  display: block;
  font-size: var(--k-fs-sm);
  color: var(--k-muted);
  transition: color 0.2s var(--k-ease), border-color 0.2s var(--k-ease);
}

.k-spylink[aria-current="true"] {
  color: var(--k-neon);
}

/* --- 11. 头部 ------------------------------------------------------------ */
.k-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background: rgba(11, 15, 20, 0.86);
  border-bottom: 1px solid var(--k-line);
  -webkit-backdrop-filter: saturate(150%) blur(16px);
  backdrop-filter: saturate(150%) blur(16px);
  transition: background-color 0.25s var(--k-ease), box-shadow 0.25s var(--k-ease);
}

.k-header[data-stuck="true"] {
  background: rgba(11, 15, 20, 0.97);
  box-shadow: 0 20px 44px -30px rgba(0, 0, 0, 1);
}

.k-header::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(43, 227, 176, 0.5) 22%, rgba(108, 124, 255, 0.34) 64%, transparent);
  opacity: 0.75;
  pointer-events: none;
}

.k-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  width: 100%;
  max-width: var(--k-shell);
  min-height: 74px;
  margin: 0 auto;
  padding: 12px var(--k-gutter);
}

.k-header__lead {
  display: flex;
  align-items: center;
  gap: 18px;
  min-width: 0;
}

.k-header__tail {
  display: flex;
  align-items: center;
  gap: 20px;
  min-width: 0;
}

.k-header__cta { flex: 0 0 auto; }

/* 跳转链接 */
.k-skip {
  position: absolute;
  top: 0;
  left: var(--k-gutter);
  z-index: 120;
  transform: translateY(-160%);
  padding: 10px 18px;
  border-radius: 0 0 var(--k-r-2) var(--k-r-2);
  background: var(--k-neon);
  color: #04231B;
  font-size: var(--k-fs-sm);
  font-weight: 700;
  transition: transform 0.2s var(--k-ease);
}

.k-skip:focus { transform: translateY(0); }

/* 品牌 */
.k-brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.k-brand__mark {
  display: grid;
  place-items: center;
  flex: 0 0 40px;
  width: 40px;
  height: 40px;
  border: 1px solid rgba(43, 227, 176, 0.55);
  border-radius: var(--k-r-3) var(--k-r-1) var(--k-r-3) var(--k-r-1);
  background:
    linear-gradient(150deg, rgba(43, 227, 176, 0.2), rgba(43, 227, 176, 0) 64%),
    var(--k-panel);
  font-family: var(--k-font-mono);
  font-size: 20px;
  font-weight: 700;
  color: var(--k-neon);
  line-height: 1;
}

.k-brand--footer .k-brand__mark {
  flex-basis: 46px;
  width: 46px;
  height: 46px;
  font-size: 23px;
}

.k-brand__text {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
  line-height: 1.15;
}

.k-brand__name {
  font-size: 17px;
  font-weight: 800;
  letter-spacing: 0.01em;
  color: var(--k-white);
  white-space: nowrap;
}

.k-brand__line {
  font-family: var(--k-font-mono);
  font-size: 10.5px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--k-muted);
  white-space: nowrap;
}

/* 轮次徽标 */
.k-roundbadge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 13px 5px 11px;
  border: 1px solid var(--k-line);
  border-left: 2px solid var(--k-signal);
  border-radius: var(--k-r-1) var(--k-r-3) var(--k-r-1) var(--k-r-3);
  background: var(--k-panel);
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.08em;
  color: var(--k-white);
  white-space: nowrap;
}

.k-roundbadge__dot {
  flex: 0 0 6px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--k-neon);
  animation: k-pulse 2.8s var(--k-ease) infinite;
}

@keyframes k-pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(43, 227, 176, 0.55); }
  60% { box-shadow: 0 0 0 6px rgba(43, 227, 176, 0); }
}

.k-headmail {
  padding-left: 18px;
  border-left: 1px solid var(--k-line);
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.04em;
  color: var(--k-muted);
  white-space: nowrap;
}

/* 导航 */
.k-nav { min-width: 0; }

.k-nav__list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.k-nav__link {
  position: relative;
  display: block;
  padding: 9px 12px;
  border-radius: var(--k-r-2) var(--k-r-1) var(--k-r-2) var(--k-r-1);
  font-size: var(--k-fs-sm);
  letter-spacing: 0.02em;
  color: rgba(232, 241, 245, 0.76);
  transition: color 0.2s var(--k-ease), background-color 0.2s var(--k-ease);
}

.k-nav__link:hover {
  color: var(--k-white);
  background: rgba(43, 227, 176, 0.08);
}

.k-nav__link[aria-current="page"] {
  color: var(--k-neon);
  background: rgba(43, 227, 176, 0.1);
}

.k-nav__link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 2px;
  height: 1px;
  background: var(--k-neon);
}

/* 抽屉按钮 */
.k-navtoggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 14px;
  border: 1px solid var(--k-line);
  border-radius: var(--k-r-3) var(--k-r-1) var(--k-r-3) var(--k-r-1);
  background: var(--k-panel);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--k-white);
}

.k-navtoggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
}

.k-navtoggle__bars::before,
.k-navtoggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 1.5px;
  background: var(--k-neon);
  transition: transform 0.24s var(--k-ease), top 0.24s var(--k-ease);
}

.k-navtoggle__bars::before { top: 0; }
.k-navtoggle__bars::after { top: 8px; }

.k-navtoggle[aria-expanded="true"] .k-navtoggle__bars::before {
  top: 4px;
  transform: rotate(45deg);
}

.k-navtoggle[aria-expanded="true"] .k-navtoggle__bars::after {
  top: 4px;
  transform: rotate(-45deg);
}

.k-navtoggle__label { font-family: var(--k-font-mono); font-size: var(--k-fs-xs); letter-spacing: 0.14em; }

/* 阅读进度 */
.k-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  overflow: hidden;
  pointer-events: none;
}

.k-progress__bar {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--k-neon), var(--k-violet) 64%, var(--k-signal));
}

@keyframes k-drawer {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: none; }
}

/* --- 12. 页脚 ------------------------------------------------------------ */
.k-footer {
  position: relative;
  margin-top: var(--k-gap-lg);
  border-top: 1px solid var(--k-line);
  background:
    linear-gradient(180deg, rgba(20, 26, 34, 0) 0%, rgba(20, 26, 34, 0.92) 26%),
    var(--k-bg);
}

.k-footer::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  width: min(260px, 34%);
  height: 2px;
  background: linear-gradient(90deg, var(--k-neon), var(--k-violet));
}

.k-footer__inner { padding-top: var(--k-gap-lg); padding-bottom: var(--k-gap-md); }

.k-footer__top {
  display: grid;
  grid-template-columns:
    minmax(240px, 1.5fr)
    repeat(3, minmax(112px, 0.8fr))
    minmax(252px, 1.4fr);
  gap: 36px;
  padding-bottom: 44px;
  border-bottom: 1px solid var(--k-line-soft);
}

.k-footer__brand { min-width: 0; }

.k-footer__title {
  margin-bottom: 16px;
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--k-muted);
}

.k-footer__list li + li { margin-top: 10px; }

.k-footer__list a {
  font-size: var(--k-fs-sm);
  color: rgba(232, 241, 245, 0.78);
  transition: color 0.2s var(--k-ease), padding-left 0.2s var(--k-ease);
}

.k-footer__list a:hover {
  color: var(--k-neon);
  padding-left: 4px;
}

.k-footer__list--contact li {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 10px;
  align-items: start;
  font-family: var(--k-font-mono);
  font-size: 13px;
  line-height: 1.7;
  color: rgba(232, 241, 245, 0.84);
  overflow-wrap: anywhere;
}

.k-footer__key {
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--k-muted);
  padding-top: 3px;
}

.k-footer__note {
  max-width: 34ch;
  margin-top: 16px;
  font-size: 13px;
  line-height: 1.8;
  color: var(--k-muted);
}

.k-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  padding-top: 24px;
  font-family: var(--k-font-mono);
  font-size: var(--k-fs-xs);
  letter-spacing: 0.06em;
  color: var(--k-muted);
}

.k-footer__legal { color: rgba(122, 138, 153, 0.95); }
.k-footer__version { color: rgba(122, 138, 153, 0.72); }

/* --- 13. 显现动效 -------------------------------------------------------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.62s var(--k-ease), transform 0.62s var(--k-ease);
}

[data-reveal][data-visible="true"] {
  opacity: 1;
  transform: none;
}

/* --- 14. 响应式 ---------------------------------------------------------- */
@media (max-width: 1180px) {
  .k-headmail { display: none; }
}

@media (max-width: 1080px) {
  .k-navtoggle { display: inline-flex; }

  .k-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    display: none;
    max-height: calc(100vh - 76px);
    overflow-y: auto;
    padding: 10px var(--k-gutter) 22px;
    background: rgba(11, 15, 20, 0.98);
    border-bottom: 1px solid var(--k-line);
    box-shadow: var(--k-shadow);
  }

  .k-nav[data-open] {
    display: block;
    animation: k-drawer 0.22s var(--k-ease);
  }

  .k-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .k-nav__item + .k-nav__item { border-top: 1px solid var(--k-line-soft); }

  .k-nav__link {
    padding: 15px 6px;
    font-size: var(--k-fs-base);
    border-radius: 0;
  }

  .k-nav__link[aria-current="page"] { background: transparent; }

  .k-nav__link[aria-current="page"]::after {
    left: 6px;
    right: auto;
    width: 20px;
    bottom: 11px;
  }

  .k-header__tail { gap: 12px; }
}

@media (max-width: 1080px) {
  .k-footer__top {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 32px;
  }

  .k-footer__brand { grid-column: 1 / -1; }
  .k-footer__contact { grid-column: 1 / -1; }
}

@media (max-width: 900px) {
  .k-grid--12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }

  .k-span-1, .k-span-2, .k-span-3, .k-span-4, .k-span-5, .k-span-6,
  .k-span-7, .k-span-8, .k-span-9, .k-span-10, .k-span-11, .k-span-12 {
    grid-column: span 6;
  }

  .k-section { padding-top: 56px; padding-bottom: 56px; }
}

@media (max-width: 720px) {
  .k-header__cta { display: none; }

  .k-header__inner {
    min-height: 64px;
    padding-top: 10px;
    padding-bottom: 10px;
    gap: 12px;
  }

  .k-header__lead { gap: 12px; }

  .k-brand__line { display: none; }
  .k-brand__mark { flex-basis: 36px; width: 36px; height: 36px; font-size: 18px; }
  .k-brand__name { font-size: 16px; }

  .k-roundbadge { font-size: 11px; padding: 4px 10px 4px 9px; }

  #main-content { scroll-margin-top: 78px; }
}

@media (max-width: 640px) {
  .k-footer__top { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 28px; }
  .k-footer__inner { padding-top: 56px; }
  .k-footer__bottom { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 620px) {
  .k-grid--12 { grid-template-columns: minmax(0, 1fr); }

  .k-span-1, .k-span-2, .k-span-3, .k-span-4, .k-span-5, .k-span-6,
  .k-span-7, .k-span-8, .k-span-9, .k-span-10, .k-span-11, .k-span-12 {
    grid-column: span 1;
  }

  .k-roundbadge { max-width: 156px; overflow: hidden; text-overflow: ellipsis; }
}

/* --- 15. 动效与可访问性 -------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .k-nav[data-open] { animation: none; }

  .k-roundbadge__dot { animation: none; }

  .k-btn:hover { transform: none; }

  .k-btn, .k-nav__link, .k-card, .k-footer__list a, .k-progress__bar {
    transition-duration: 0.01ms;
  }
}