/* =========================================================
   开元中心 · Site Kit / assets/site.css
   ========================================================= */

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

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

body { margin: 0; }

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

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

a { color: inherit; }

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

h1, h2, h3, h4, h5, h6, p, figure, blockquote { margin: 0; }

:root {
  --k-deep: #0B1F24;
  --k-black: #071316;
  --k-cream: #F7F3EA;
  --k-red: #D23B2E;
  --k-red-deep: #9E241B;
  --k-amber: #F59A23;
  --k-gold: #FFD08A;
  --k-teal: #1E5A55;
  --k-teal-light: #7EC8BC;
  --k-mist: #B9C4C2;

  --k-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", -apple-system, "Segoe UI", sans-serif;
  --k-shell: 1280px;
  --k-radius: 20px;
  --k-ease: cubic-bezier(.22, .61, .36, 1);
  --k-gutter: clamp(18px, 4vw, 48px);
}

html { font-family: var(--k-sans); }

body {
  background: var(--k-deep);
  color: var(--k-cream);
  font-family: var(--k-sans);
  font-size: 17px;
  font-weight: 400;
  line-height: 1.75;
  word-break: break-word;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

:focus-visible {
  outline: 2px solid var(--k-amber);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---------- 容器与章节 ---------- */

.k-shell {
  width: 100%;
  max-width: var(--k-shell);
  margin-inline: auto;
  padding-inline: var(--k-gutter);
}

.k-section {
  position: relative;
  padding-block: clamp(46px, 7vw, 96px);
}

.k-section__title {
  font-size: clamp(2rem, 4vw, 3.6rem);
  font-weight: 900;
  line-height: 1.06;
  letter-spacing: -.02em;
  text-wrap: balance;
}

.k-em {
  font-style: normal;
  font-weight: 200;
  color: var(--k-amber);
}

.k-eyebrow {
  display: flex;
  align-items: center;
  gap: .75em;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .28em;
  text-transform: uppercase;
  color: var(--k-amber);
}

.k-eyebrow::before {
  content: "";
  width: 26px;
  height: 2px;
  flex: 0 0 auto;
  background: linear-gradient(90deg, var(--k-red), var(--k-amber));
}

.k-lede {
  font-size: clamp(16px, 1.6vw, 19px);
  font-weight: 300;
  line-height: 1.8;
  color: var(--k-mist);
  max-width: 34em;
}

.k-num { font-variant-numeric: tabular-nums; letter-spacing: .02em; }

/* ---------- 层 ---------- */

.k-layer--light { background: var(--k-cream); color: var(--k-deep); }
.k-layer--teal { background: var(--k-teal); color: var(--k-cream); }
.k-layer--light .k-lede { color: rgba(11, 31, 36, .74); }

/* ---------- 网格 ---------- */

.k-grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(14px, 2vw, 28px);
}

.k-split {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: clamp(24px, 4vw, 64px);
  align-items: start;
}

/* ---------- 色带 ---------- */

.k-band {
  height: 12px;
  background: linear-gradient(90deg, var(--k-red) 0%, var(--k-amber) 38%, var(--k-teal) 74%, var(--k-red) 100%);
}

.k-band--thin { height: 5px; }

.k-band--footer {
  height: 8px;
  background: linear-gradient(90deg, var(--k-red) 0%, var(--k-amber) 34%, var(--k-teal) 68%, var(--k-red) 100%);
}

/* ---------- 正文排版 ---------- */

.k-prose {
  max-width: 68ch;
  font-size: 17px;
  line-height: 1.85;
}

.k-prose h2 {
  font-size: clamp(1.5rem, 2.4vw, 2rem);
  font-weight: 900;
  line-height: 1.24;
  letter-spacing: -.01em;
  margin: 2em 0 .7em;
}

.k-prose h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 1.6em 0 .5em;
}

.k-prose p { margin: 0 0 1.1em; }

.k-prose ul,
.k-prose ol {
  list-style: disc;
  padding-left: 1.35em;
  margin: 0 0 1.1em;
}

.k-prose ol { list-style: decimal; }

.k-prose li { margin: .4em 0; }

.k-prose a {
  color: var(--k-red);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.k-layer--light .k-prose a { color: var(--k-red-deep); }

.k-prose strong { font-weight: 700; }

/* ---------- 按钮 ---------- */

.k-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .55em;
  padding: .82em 1.55em;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .04em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color .2s var(--k-ease), color .2s var(--k-ease), border-color .2s var(--k-ease), transform .2s var(--k-ease);
}

.k-btn:hover { transform: translateY(-2px); }
.k-btn:active { transform: translateY(0); }

.k-btn--solid { background: var(--k-red); color: var(--k-cream); }
.k-btn--solid:hover { background: var(--k-red-deep); }

.k-btn--amber { background: var(--k-amber); color: var(--k-black); }
.k-btn--amber:hover { background: var(--k-gold); }

.k-btn--ghost {
  background: transparent;
  color: var(--k-cream);
  border-color: rgba(255, 208, 138, .38);
}

.k-btn--ghost:hover { border-color: var(--k-amber); color: var(--k-gold); }

.k-layer--light .k-btn--ghost {
  color: var(--k-deep);
  border-color: rgba(11, 31, 36, .28);
}

.k-layer--light .k-btn--ghost:hover {
  border-color: var(--k-red);
  color: var(--k-red-deep);
}

/* ---------- 标签 / 卡片 / 玻璃层 ---------- */

.k-tag {
  display: inline-flex;
  align-items: center;
  padding: .32em .85em;
  border-radius: 999px;
  border: 1px solid rgba(245, 154, 35, .34);
  background: rgba(245, 154, 35, .14);
  color: var(--k-gold);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .12em;
  line-height: 1.5;
}

.k-layer--light .k-tag {
  background: rgba(210, 59, 46, .1);
  border-color: rgba(210, 59, 46, .28);
  color: var(--k-red-deep);
}

.k-card {
  background: var(--k-cream);
  color: var(--k-deep);
  border-radius: var(--k-radius);
  padding: clamp(20px, 3vw, 34px);
  box-shadow: 0 18px 44px rgba(7, 19, 22, .28);
}

.k-glass {
  background: rgba(30, 90, 85, .32);
  border: 1px solid rgba(255, 208, 138, .24);
  border-radius: 22px;
  padding: clamp(18px, 2.6vw, 28px);
  color: var(--k-cream);
  -webkit-backdrop-filter: blur(14px) saturate(1.15);
  backdrop-filter: blur(14px) saturate(1.15);
}

/* ---------- 图片容器 ---------- */

.k-media {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  aspect-ratio: 4 / 3;
  border-radius: var(--k-radius);
  background:
    radial-gradient(120% 130% at 50% 118%, #FFD08A 0%, #F59A23 16%, #D23B2E 40%, #0B1F24 78%);
  box-shadow: inset 0 0 0 1px rgba(255, 208, 138, .2);
}

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

.k-media__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.k-media__placeholder {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 1.2em;
  text-align: center;
  color: rgba(247, 243, 234, .76);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: .3em;
  text-transform: uppercase;
}

/* ---------- 面包屑 ---------- */

.k-breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .55em;
  font-size: 12.5px;
  letter-spacing: .14em;
  color: var(--k-mist);
}

.k-breadcrumb a {
  color: inherit;
  text-decoration: none;
  transition: color .2s var(--k-ease);
}

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

.k-breadcrumb [aria-current="page"] { color: var(--k-gold); font-weight: 600; }

.k-breadcrumb__sep { opacity: .45; }

/* ---------- 目录高亮状态 ---------- */

[data-toc-for] { color: inherit; }

[data-toc-for][aria-current="true"] {
  color: var(--k-amber);
  font-weight: 700;
}

/* ---------- 跳转链接 ---------- */

.k-skip {
  position: fixed;
  top: 10px;
  left: 50%;
  z-index: 200;
  padding: .68em 1.3em;
  border-radius: 999px;
  background: var(--k-amber);
  color: var(--k-black);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  transform: translate(-50%, -180%);
  transition: transform .2s var(--k-ease);
}

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

/* =========================================================
   头部
   ========================================================= */

.k-header {
  position: sticky;
  top: 0;
  z-index: 120;
  padding: clamp(8px, 1.2vw, 14px) clamp(10px, 2.6vw, 26px) clamp(10px, 1.4vw, 18px);
  background: linear-gradient(180deg, rgba(7, 19, 22, .95) 0%, rgba(7, 19, 22, .66) 62%, rgba(7, 19, 22, 0) 100%);
}

.k-header__inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(10px, 2vw, 26px);
  max-width: var(--k-shell);
  margin-inline: auto;
  padding: 8px 10px 8px 14px;
  border: 1px solid rgba(255, 208, 138, .18);
  border-radius: 999px;
  background: rgba(7, 19, 22, .74);
  box-shadow: 0 12px 34px rgba(0, 0, 0, .38);
  -webkit-backdrop-filter: blur(16px) saturate(1.2);
  backdrop-filter: blur(16px) saturate(1.2);
}

.k-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
  text-decoration: none;
  color: var(--k-cream);
}

.k-brand__mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 14px;
  background: linear-gradient(142deg, var(--k-red), var(--k-red-deep));
  color: var(--k-gold);
  font-size: 20px;
  font-weight: 900;
  line-height: 1;
  box-shadow: inset 0 0 0 1px rgba(255, 208, 138, .28), 0 6px 16px rgba(210, 59, 46, .32);
}

.k-brand__text {
  display: flex;
  flex-direction: column;
  gap: 2px;
  line-height: 1.1;
}

.k-brand__name {
  font-size: 17px;
  font-weight: 900;
  letter-spacing: .07em;
  white-space: nowrap;
}

.k-brand__tag {
  font-size: 10.5px;
  font-weight: 600;
  letter-spacing: .34em;
  color: var(--k-amber);
  white-space: nowrap;
}

.k-nav {
  display: flex;
  align-items: center;
  gap: clamp(2px, .6vw, 10px);
}

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

.k-nav__link {
  display: inline-block;
  padding: .55em .92em;
  border-radius: 999px;
  font-size: 14.5px;
  font-weight: 500;
  letter-spacing: .04em;
  color: rgba(247, 243, 234, .84);
  text-decoration: none;
  white-space: nowrap;
  transition: color .2s var(--k-ease), background-color .2s var(--k-ease), box-shadow .2s var(--k-ease);
}

.k-nav__link:hover {
  color: var(--k-gold);
  background: rgba(245, 154, 35, .12);
}

.k-nav__link[aria-current="page"] {
  color: var(--k-gold);
  background: rgba(245, 154, 35, .16);
  box-shadow: inset 0 -2px 0 var(--k-amber);
}

.k-nav__cta {
  display: inline-flex;
  align-items: center;
  gap: .42em;
  margin-left: 6px;
  padding: .58em 1.12em;
  border-radius: 999px;
  background: var(--k-red);
  color: var(--k-cream);
  font-size: 14.5px;
  font-weight: 700;
  letter-spacing: .06em;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color .2s var(--k-ease), transform .2s var(--k-ease);
}

.k-nav__cta::after {
  content: "→";
  font-size: .92em;
  line-height: 1;
}

.k-nav__cta:hover { background: var(--k-red-deep); transform: translateY(-1px); }

.k-nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: .55em .95em;
  border: 1px solid rgba(255, 208, 138, .3);
  border-radius: 999px;
  background: rgba(30, 90, 85, .38);
  color: var(--k-cream);
  font-size: 13.5px;
  font-weight: 600;
  cursor: pointer;
}

.k-nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 16px;
}

.k-nav-toggle__bars span {
  display: block;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform .22s var(--k-ease);
}

.k-nav-toggle[aria-expanded="true"] .k-nav-toggle__bars span:first-child {
  transform: translateY(3px) rotate(45deg);
}

.k-nav-toggle[aria-expanded="true"] .k-nav-toggle__bars span:last-child {
  transform: translateY(-3px) rotate(-45deg);
}

.k-nav-toggle__label {
  font-size: 13px;
  letter-spacing: .1em;
}

.k-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  background: rgba(255, 208, 138, .1);
  pointer-events: none;
}

.k-progress__bar {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: left center;
  background: linear-gradient(90deg, var(--k-red), var(--k-amber) 55%, var(--k-gold));
}

/* =========================================================
   页脚
   ========================================================= */

.k-footer {
  position: relative;
  margin-top: clamp(48px, 8vw, 96px);
  background: var(--k-black);
  color: var(--k-cream);
}

.k-footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) repeat(2, minmax(0, .78fr)) minmax(0, 1.15fr);
  gap: clamp(24px, 4vw, 56px);
  padding-block: clamp(40px, 6vw, 76px);
}

.k-footer__brand {
  position: relative;
  isolation: isolate;
}

.k-footer__brand::before {
  content: "";
  position: absolute;
  top: -46px;
  right: -10px;
  z-index: -1;
  width: 190px;
  height: 190px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(245, 154, 35, .3) 0%, rgba(210, 59, 46, .14) 46%, rgba(210, 59, 46, 0) 72%);
  filter: blur(6px);
  pointer-events: none;
}

.k-footer__logo {
  font-size: clamp(28px, 3.6vw, 40px);
  font-weight: 900;
  line-height: 1.05;
  letter-spacing: .04em;
  color: var(--k-cream);
  text-wrap: balance;
}

.k-footer__logo::after {
  content: "";
  display: inline-block;
  width: .3em;
  height: .3em;
  margin-left: .16em;
  border-radius: 50%;
  background: var(--k-amber);
  vertical-align: baseline;
}

.k-footer__tagline {
  margin-top: .7em;
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: .32em;
  text-transform: uppercase;
  color: var(--k-amber);
}

.k-footer__note {
  margin-top: 1.15em;
  max-width: 26em;
  font-size: 14px;
  font-weight: 300;
  line-height: 1.8;
  color: var(--k-mist);
}

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

.k-footer__title {
  margin: 0 0 1em;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .3em;
  text-transform: uppercase;
  color: var(--k-teal-light);
}

.k-footer__list {
  display: grid;
  gap: .7em;
}

.k-footer__link {
  font-size: 15px;
  font-weight: 400;
  color: rgba(247, 243, 234, .84);
  text-decoration: none;
  transition: color .2s var(--k-ease);
}

.k-footer__link:hover { color: var(--k-gold); }

.k-footer__contact-list {
  display: grid;
  gap: .95em;
}

.k-footer__contact-item {
  display: grid;
  gap: .22em;
}

.k-footer__label {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .26em;
  text-transform: uppercase;
  color: var(--k-mist);
}

.k-footer__value {
  font-size: 15px;
  font-weight: 500;
  line-height: 1.6;
  color: var(--k-cream);
  word-break: break-word;
}

.k-footer__hint {
  margin-top: 1.25em;
  padding-left: .9em;
  border-left: 2px solid var(--k-amber);
  font-size: 12.5px;
  line-height: 1.7;
  color: rgba(185, 196, 194, .88);
}

.k-footer__legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  padding-block: 22px;
  border-top: 1px solid rgba(185, 196, 194, .16);
  font-size: 12.5px;
  color: rgba(185, 196, 194, .9);
}

.k-footer__icp { margin: 0; }

.k-footer__legal-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
}

.k-footer__legal-links .k-footer__link {
  font-size: 12.5px;
  color: rgba(185, 196, 194, .9);
}

.k-footer__legal-links .k-footer__link:hover { color: var(--k-gold); }

/* =========================================================
   动效
   ========================================================= */

.k-js [data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity .7s var(--k-ease), transform .7s var(--k-ease);
}

.k-js [data-reveal].is-revealed {
  opacity: 1;
  transform: none;
}

/* =========================================================
   响应式
   ========================================================= */

@media (max-width: 1023px) {
  .k-footer__top {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .k-footer__brand { grid-column: 1 / -1; }
  .k-footer__brand::before { right: auto; left: 0; }
}

@media (max-width: 959px) {
  .k-nav {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 6px;
    max-height: min(70vh, 520px);
    overflow: auto;
    padding: 14px;
    border: 1px solid rgba(255, 208, 138, .22);
    border-radius: 24px;
    background: rgba(7, 19, 22, .97);
    box-shadow: 0 26px 64px rgba(0, 0, 0, .55);
    -webkit-backdrop-filter: blur(18px);
    backdrop-filter: blur(18px);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity .22s var(--k-ease), transform .22s var(--k-ease), visibility .22s var(--k-ease);
  }

  .k-nav[data-open="true"] {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .k-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .k-nav__link {
    display: block;
    padding: .8em 1em;
    border-radius: 14px;
    font-size: 16px;
  }

  .k-nav__link[aria-current="page"] {
    box-shadow: inset 3px 0 0 var(--k-amber);
  }

  .k-nav__cta {
    justify-content: center;
    margin: 8px 0 0;
    padding: .86em 1.1em;
    font-size: 16px;
  }

  .k-nav-toggle { display: inline-flex; }

  .k-brand__name { font-size: 15.5px; }
  .k-brand__tag { font-size: 9.5px; letter-spacing: .28em; }
  .k-brand__mark { width: 36px; height: 36px; font-size: 18px; border-radius: 12px; }

  .k-split { grid-template-columns: minmax(0, 1fr); }
  .k-grid { grid-template-columns: repeat(6, minmax(0, 1fr)); }
}

@media (max-width: 620px) {
  body { font-size: 16px; }
  .k-footer__top { grid-template-columns: minmax(0, 1fr); }
  .k-footer__legal {
    flex-direction: column;
    align-items: flex-start;
  }
  .k-btn { font-size: 15px; padding: .78em 1.3em; }
  .k-nav-toggle__label { display: none; }
  .k-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

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

  .k-js [data-reveal] {
    opacity: 1;
    transform: none;
  }

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