/* ==========================================================
   星游中心 · 共享样式表 /assets/site.css
   深空蓝图：坐标网格 + 舷窗容器 + 冷色宇宙 / 暖色导航
   ========================================================== */

/* ---------- 1. 变量 ---------- */
:root {
  --c-void: #05070E;
  --c-deep: #0A0F1E;
  --c-window: #101A33;
  --c-nebula: #7C5CFF;
  --c-electric: #46E5FF;
  --c-amber: #FFC65C;
  --c-star: #E8EDFF;
  --c-dust: #9AA7C7;
  --c-orbit: #C0CCE8;
  --c-rose: #FF6B9D;

  --c-line: rgba(192, 204, 232, 0.16);
  --c-line-strong: rgba(192, 204, 232, 0.34);
  --c-glass: rgba(16, 26, 51, 0.72);
  --c-glass-soft: rgba(16, 26, 51, 0.42);

  --f-display: "Exo 2", "Rajdhani", "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --f-body: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --f-mono: ui-monospace, "SFMono-Regular", "Cascadia Mono", Consolas, "Liberation Mono", monospace;

  --w-shell: 1400px;
  --w-read: 72ch;
  --pad-x: clamp(16px, 4vw, 40px);
  --gap: clamp(16px, 2.4vw, 32px);
  --header-h: 70px;

  --r-sm: 2px;
  --r-md: 3px;
  --r-lg: 6px;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur: 0.28s;
}

/* ---------- 2. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  background-color: var(--c-void);
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 20px);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100%;
  position: relative;
  background: var(--c-void);
  color: var(--c-star);
  font-family: var(--f-body);
  font-size: 16px;
  line-height: 1.75;
  font-weight: 400;
  letter-spacing: 0.01em;
  overflow-x: hidden;
}

/* 蓝图坐标网格（固定层） */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(192, 204, 232, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(192, 204, 232, 0.05) 1px, transparent 1px);
  background-size: 64px 64px;
  background-position: center top;
}

/* 星云辉光（固定层） */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(880px 620px at 82% -12%, rgba(124, 92, 255, 0.22), transparent 68%),
    radial-gradient(680px 520px at 4% 8%, rgba(70, 229, 255, 0.12), transparent 70%),
    radial-gradient(900px 700px at 50% 118%, rgba(124, 92, 255, 0.12), transparent 72%);
}

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

img { height: auto; }

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 0.6em;
  font-family: var(--f-display);
  font-weight: 600;
  line-height: 1.24;
  letter-spacing: 0.05em;
  color: var(--c-star);
}

p { margin: 0 0 1.1em; }

a { color: var(--c-electric); text-decoration: none; }
a:hover { color: #8CF0FF; }

ul, ol { margin: 0 0 1.1em; padding-left: 1.15em; }

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

address { font-style: normal; }

hr {
  border: 0;
  height: 1px;
  background: var(--c-line);
  margin: 2rem 0;
}

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

:where(a, button, [tabindex], input, select, textarea):focus-visible {
  outline: 2px solid var(--c-electric);
  outline-offset: 3px;
  border-radius: var(--r-sm);
}

::selection {
  background: rgba(70, 229, 255, 0.28);
  color: #FFFFFF;
}

/* ---------- 3. 层级与主容器 ---------- */
.sg-header,
.sg-main,
.sg-footer {
  position: relative;
  z-index: 1;
}

.sg-main {
  display: block;
  min-height: 40vh;
  padding-bottom: clamp(48px, 8vw, 110px);
}

.sg-container {
  width: 100%;
  max-width: var(--w-shell);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

.sg-container--read { max-width: calc(var(--w-read) + var(--pad-x) * 2); }

/* ---------- 4. 跳过链接 ---------- */
.sg-skip {
  position: absolute;
  left: 14px;
  top: -120px;
  z-index: 220;
  display: inline-block;
  padding: 10px 18px;
  background: var(--c-electric);
  color: #04121A;
  font-family: var(--f-display);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  border-radius: var(--r-sm);
  box-shadow: 0 8px 26px -8px rgba(70, 229, 255, 0.8);
  transition: top 0.22s var(--ease);
}

.sg-skip:focus {
  top: 12px;
  color: #04121A;
}

/* ---------- 5. 头部命令栏 ---------- */
.sg-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background: linear-gradient(180deg, rgba(10, 15, 30, 0.96), rgba(5, 7, 14, 0.92));
  border-bottom: 1px solid var(--c-line);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}

.sg-header__inner {
  position: relative;
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 26px);
  width: 100%;
  max-width: var(--w-shell);
  min-height: var(--header-h);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

.sg-header__rail {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 1px;
  background: linear-gradient(90deg, transparent 2%, rgba(70, 229, 255, 0.55) 26%, rgba(124, 92, 255, 0.6) 62%, transparent 98%);
  opacity: 0.7;
  pointer-events: none;
}

/* 品牌 */
.sg-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
  padding: 6px 10px 6px 6px;
  border: 1px solid transparent;
  border-radius: var(--r-sm);
  color: var(--c-star);
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.sg-brand:hover {
  color: var(--c-star);
  border-color: var(--c-line);
  background: rgba(70, 229, 255, 0.05);
}

.sg-brand__mark {
  width: 32px;
  height: 32px;
  flex: 0 0 auto;
  overflow: visible;
}

.sg-brand__text {
  display: inline-flex;
  align-items: baseline;
  gap: 5px;
  line-height: 1;
}

.sg-brand__name {
  font-family: var(--f-display);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--c-star);
}

.sg-brand__suffix {
  font-family: var(--f-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--c-electric);
  padding: 2px 5px;
  border: 1px solid rgba(70, 229, 255, 0.45);
  border-radius: var(--r-sm);
}

/* 命令栏导航 */
.sg-nav {
  display: flex;
  align-items: center;
  flex: 1 1 auto;
  min-width: 0;
}

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

.sg-nav__item { flex: 0 0 auto; }

.sg-nav__link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 9px 11px;
  border: 1px solid transparent;
  border-radius: var(--r-sm);
  color: var(--c-dust);
  font-family: var(--f-display);
  font-size: 14px;
  letter-spacing: 0.07em;
  white-space: nowrap;
  transition: color var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}

.sg-nav__idx {
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.06em;
  color: rgba(154, 167, 199, 0.6);
  transition: color var(--dur) var(--ease);
}

.sg-nav__link:hover {
  color: var(--c-star);
  background: rgba(70, 229, 255, 0.07);
  border-color: rgba(70, 229, 255, 0.3);
}

.sg-nav__link:hover .sg-nav__idx { color: var(--c-electric); }

.sg-nav__link[aria-current="page"] {
  color: var(--c-electric);
  background: rgba(70, 229, 255, 0.1);
  border-color: rgba(70, 229, 255, 0.5);
  box-shadow: inset 0 -2px 0 0 var(--c-electric);
}

.sg-nav__link[aria-current="page"] .sg-nav__idx { color: var(--c-electric); }

.sg-nav__cta {
  display: none;
  margin: 6px 0 2px;
  padding: 12px 18px;
  text-align: center;
  font-family: var(--f-display);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--c-amber);
  border: 1px solid rgba(255, 198, 92, 0.55);
  border-radius: var(--r-sm);
  background: linear-gradient(135deg, rgba(255, 198, 92, 0.16), rgba(255, 198, 92, 0.04));
}

.sg-nav__cta:hover {
  color: #FFD98F;
  border-color: var(--c-amber);
}

/* 桌面收藏按钮 */
.sg-header__aside {
  margin-left: auto;
  display: flex;
  align-items: center;
  flex: 0 0 auto;
}

.sg-cta {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  font-family: var(--f-display);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.08em;
  white-space: nowrap;
  color: var(--c-amber);
  border: 1px solid var(--c-amber);
  border-radius: var(--r-sm);
  background: linear-gradient(135deg, rgba(255, 198, 92, 0.18), rgba(255, 198, 92, 0.05));
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.sg-cta::before {
  content: "";
  position: absolute;
  inset: -3px;
  border: 1px solid rgba(255, 198, 92, 0.45);
  border-radius: var(--r-sm);
  pointer-events: none;
  animation: sg-cta-ring 3.4s ease-in-out infinite;
}

.sg-cta:hover {
  color: #FFF3D6;
  background: linear-gradient(135deg, rgba(255, 198, 92, 0.3), rgba(255, 198, 92, 0.1));
}

@keyframes sg-cta-ring {
  0%, 100% { opacity: 0.3; transform: scale(1); }
  50% { opacity: 0.95; transform: scale(1.05); }
}

/* 汉堡按钮 */
.sg-burger {
  display: none;
  align-items: center;
  gap: 9px;
  margin-left: auto;
  padding: 8px 12px;
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-sm);
  background: rgba(16, 26, 51, 0.6);
  color: var(--c-star);
  font-family: var(--f-display);
  font-size: 13px;
  letter-spacing: 0.1em;
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.sg-burger:hover { border-color: rgba(70, 229, 255, 0.6); background: rgba(70, 229, 255, 0.08); }

.sg-burger__bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: space-between;
  width: 18px;
  height: 13px;
}

.sg-burger__bar {
  display: block;
  height: 1.5px;
  width: 100%;
  background: var(--c-electric);
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}

.sg-header[data-open] .sg-burger__bar:nth-child(1) { transform: translateY(5.75px) rotate(45deg); }
.sg-header[data-open] .sg-burger__bar:nth-child(2) { opacity: 0; }
.sg-header[data-open] .sg-burger__bar:nth-child(3) { transform: translateY(-5.75px) rotate(-45deg); }

/* ---------- 6. 响应式导航（≤1023px 抽屉） ---------- */
@media (max-width: 1023px) {
  .sg-burger { display: inline-flex; }

  .sg-header__aside { display: none; }

  .sg-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    display: block;
    padding: 14px var(--pad-x) 20px;
    background: linear-gradient(180deg, rgba(8, 12, 26, 0.99), rgba(5, 7, 14, 0.99));
    border-bottom: 1px solid var(--c-line-strong);
    box-shadow: 0 26px 48px -30px rgba(0, 0, 0, 0.95);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.24s var(--ease),
                transform 0.24s var(--ease),
                visibility 0.24s linear;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
  }

  .sg-header[data-open] .sg-nav {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .sg-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
  }

  .sg-nav__item { width: 100%; }

  .sg-nav__link {
    width: 100%;
    justify-content: flex-start;
    padding: 13px 14px;
    font-size: 15px;
    border-color: rgba(192, 204, 232, 0.12);
    background: rgba(16, 26, 51, 0.4);
  }

  .sg-nav__idx { font-size: 11px; }

  .sg-nav__cta { display: block; }
}

@media (min-width: 1024px) {
  .sg-nav { justify-content: flex-end; }
  .sg-nav__cta { display: none; }
}

/* ---------- 7. 页脚 ---------- */
.sg-footer {
  background: linear-gradient(180deg, var(--c-deep) 0%, var(--c-void) 100%);
  border-top: 1px solid var(--c-line);
}

.sg-footer__inner {
  width: 100%;
  max-width: var(--w-shell);
  margin-inline: auto;
  padding: clamp(44px, 6vw, 78px) var(--pad-x) 0;
}

.sg-footer__grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.35fr;
  gap: clamp(24px, 3.6vw, 56px);
  padding-bottom: clamp(32px, 4vw, 52px);
}

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

.sg-footer__col--brand {
  padding-right: clamp(0px, 2vw, 32px);
}

.sg-footer__brand {
  margin: 0 0 10px;
  font-family: var(--f-display);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--c-star);
}

.sg-footer__brand::after {
  content: "";
  display: block;
  width: 46px;
  height: 1px;
  margin-top: 12px;
  background: linear-gradient(90deg, var(--c-electric), rgba(124, 92, 255, 0.4), transparent);
}

.sg-footer__meta {
  margin: 0 0 6px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--c-dust);
  letter-spacing: 0.03em;
}

.sg-footer__meta--code {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: rgba(154, 167, 199, 0.75);
}

.sg-footer__title {
  margin: 0 0 14px;
  font-family: var(--f-display);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--c-orbit);
}

.sg-footer__title::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  margin-right: 8px;
  vertical-align: middle;
  border: 1px solid var(--c-electric);
  transform: rotate(45deg);
}

.sg-footer__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.sg-footer__item {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--c-dust);
}

.sg-footer__link {
  position: relative;
  display: inline-block;
  color: var(--c-dust);
  transition: color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.sg-footer__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 0;
  height: 1px;
  background: var(--c-electric);
  transition: width var(--dur) var(--ease);
}

.sg-footer__link:hover {
  color: var(--c-electric);
  transform: translateX(2px);
}

.sg-footer__link:hover::after { width: 100%; }

.sg-footer__key {
  flex: 0 0 auto;
  min-width: 34px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: rgba(70, 229, 255, 0.75);
  padding-top: 2px;
}

.sg-footer__contact {
  flex: 1 1 160px;
  min-width: 0;
  color: var(--c-orbit);
  word-break: break-word;
}

.sg-footer__base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 20px 0 26px;
  border-top: 1px solid var(--c-line);
}

.sg-footer__copy {
  margin: 0;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: rgba(154, 167, 199, 0.8);
}

.sg-footer__motto {
  margin: 0;
  font-family: var(--f-display);
  font-size: 14px;
  letter-spacing: 0.36em;
  color: var(--c-amber);
  text-shadow: 0 0 18px rgba(255, 198, 92, 0.4);
}

@media (max-width: 900px) {
  .sg-footer__grid { grid-template-columns: 1fr 1fr; }
  .sg-footer__col--brand { grid-column: 1 / -1; }
}

@media (max-width: 560px) {
  .sg-footer__grid { grid-template-columns: 1fr; gap: 30px; }
  .sg-footer__base { justify-content: flex-start; }
}

/* ---------- 8. 通用章节与排版工具 ---------- */
.sg-section {
  padding-block: clamp(42px, 7vw, 96px);
  position: relative;
}

.sg-section + .sg-section { border-top: 1px solid var(--c-line); }

.sg-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 16px;
  font-family: var(--f-mono);
  font-size: 11.5px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--c-electric);
}

.sg-eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--c-electric);
  opacity: 0.7;
}

.sg-section__title {
  font-size: clamp(26px, 3.4vw, 40px);
  letter-spacing: 0.06em;
  margin-bottom: 0.5em;
}

.sg-section__title--xl {
  font-size: clamp(32px, 5.2vw, 64px);
  letter-spacing: 0.05em;
}

.sg-lead {
  max-width: var(--w-read);
  font-size: clamp(15px, 1.4vw, 17px);
  line-height: 1.85;
  color: var(--c-dust);
}

.sg-note {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: rgba(154, 167, 199, 0.8);
}

/* ---------- 9. 网格与舷窗容器 ---------- */
.sg-grid {
  display: grid;
  gap: var(--gap);
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.sg-grid--2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.sg-grid--3 { grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }

.sg-grid--split {
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  align-items: start;
}

@media (max-width: 860px) {
  .sg-grid--split { grid-template-columns: 1fr; }
}

.sg-panel {
  position: relative;
  padding: clamp(20px, 2.6vw, 32px);
  border: 1px solid var(--c-line);
  border-radius: var(--r-md);
  background:
    linear-gradient(180deg, rgba(16, 26, 51, 0.82), rgba(8, 12, 26, 0.72));
  overflow: hidden;
}

.sg-panel::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(70, 229, 255, 0.6), transparent);
}

.sg-panel--amber::before {
  background: linear-gradient(90deg, transparent, rgba(255, 198, 92, 0.7), transparent);
}

.sg-panel > *:last-child { margin-bottom: 0; }

.sg-tag {
  display: inline-block;
  padding: 3px 9px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--c-electric);
  border: 1px solid rgba(70, 229, 255, 0.4);
  border-radius: var(--r-sm);
  background: rgba(70, 229, 255, 0.07);
}

.sg-tag--nebula {
  color: #C9BAFF;
  border-color: rgba(124, 92, 255, 0.5);
  background: rgba(124, 92, 255, 0.12);
}

.sg-tag--amber {
  color: var(--c-amber);
  border-color: rgba(255, 198, 92, 0.5);
  background: rgba(255, 198, 92, 0.1);
}

/* ---------- 10. 按钮 ---------- */
.sg-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 12px 22px;
  font-family: var(--f-display);
  font-size: 14.5px;
  font-weight: 600;
  letter-spacing: 0.08em;
  border: 1px solid var(--c-line-strong);
  border-radius: var(--r-sm);
  color: var(--c-star);
  background: rgba(16, 26, 51, 0.6);
  transition: color var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              transform var(--dur) var(--ease);
}

.sg-btn:hover {
  color: var(--c-star);
  border-color: rgba(70, 229, 255, 0.6);
  background: rgba(70, 229, 255, 0.1);
  transform: translateY(-1px);
}

.sg-btn--amber {
  color: #1B1204;
  border-color: var(--c-amber);
  background: linear-gradient(135deg, #FFD98F, var(--c-amber));
  box-shadow: 0 14px 34px -18px rgba(255, 198, 92, 0.9);
}

.sg-btn--amber:hover {
  color: #1B1204;
  border-color: #FFE2AC;
  background: linear-gradient(135deg, #FFE7B6, #FFD070);
}

.sg-btn--ghost {
  background: transparent;
  color: var(--c-electric);
  border-color: rgba(70, 229, 255, 0.45);
}

.sg-btn--ghost:hover {
  color: #A6F3FF;
  background: rgba(70, 229, 255, 0.08);
}

/* ---------- 11. 面包屑 ---------- */
.sg-breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 18px 0 0;
  list-style: none;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: rgba(154, 167, 199, 0.85);
}

.sg-breadcrumb__item { display: inline-flex; align-items: center; gap: 8px; }

.sg-breadcrumb__item + .sg-breadcrumb__item::before {
  content: "/";
  color: rgba(70, 229, 255, 0.55);
}

.sg-breadcrumb__item a { color: var(--c-dust); }
.sg-breadcrumb__item a:hover { color: var(--c-electric); }
.sg-breadcrumb__item [aria-current="page"] { color: var(--c-orbit); }

/* ---------- 12. 媒体容器（舷窗） ---------- */
.sg-media {
  position: relative;
  display: block;
  width: 100%;
  overflow: hidden;
  isolation: isolate;
  border: 1px solid var(--c-line);
  border-radius: var(--r-md);
  background:
    linear-gradient(150deg, rgba(124, 92, 255, 0.16), rgba(70, 229, 255, 0.07) 46%, rgba(5, 7, 14, 0.95));
}

.sg-media::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  background-image:
    linear-gradient(rgba(192, 204, 232, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(192, 204, 232, 0.07) 1px, transparent 1px);
  background-size: 30px 30px;
}

.sg-media::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  background:
    radial-gradient(120% 90% at 84% 0%, rgba(70, 229, 255, 0.18), transparent 62%),
    radial-gradient(90% 70% at 8% 110%, rgba(124, 92, 255, 0.22), transparent 66%);
}

.sg-media > img,
.sg-media > svg,
.sg-media > picture > img {
  position: relative;
  z-index: 1;
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.sg-media--21x9 { aspect-ratio: 21 / 9; }
.sg-media--16x9 { aspect-ratio: 16 / 9; }
.sg-media--3x2  { aspect-ratio: 3 / 2; }
.sg-media--4x3  { aspect-ratio: 4 / 3; }
.sg-media--1x1  { aspect-ratio: 1 / 1; }

.sg-media__tag {
  position: absolute;
  z-index: 2;
  top: 12px;
  left: 12px;
  padding: 3px 9px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--c-amber);
  border: 1px solid rgba(255, 198, 92, 0.5);
  border-radius: var(--r-sm);
  background: rgba(5, 7, 14, 0.72);
}

.sg-media__caption {
  position: relative;
  z-index: 2;
  margin: 0;
  padding: 10px 14px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--c-dust);
  border-top: 1px solid var(--c-line);
  background: rgba(5, 7, 14, 0.7);
}

/* ---------- 13. 分段切换（可访问标签页） ---------- */
.sg-tabs { margin-block: 24px; }

.sg-tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  padding: 6px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-md);
  background: rgba(10, 15, 30, 0.7);
}

.sg-tabs__tab {
  padding: 9px 16px;
  font-family: var(--f-display);
  font-size: 13.5px;
  letter-spacing: 0.07em;
  color: var(--c-dust);
  border: 1px solid transparent;
  border-radius: var(--r-sm);
  transition: color var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}

.sg-tabs__tab:hover {
  color: var(--c-star);
  background: rgba(70, 229, 255, 0.07);
}

.sg-tabs__tab[aria-selected="true"] {
  color: #04121A;
  background: linear-gradient(135deg, var(--c-electric), #7CD9FF);
  border-color: var(--c-electric);
  box-shadow: 0 10px 26px -14px rgba(70, 229, 255, 0.9);
}

.sg-tabs__panel {
  margin-top: 18px;
  padding: clamp(18px, 2.4vw, 28px);
  border: 1px solid var(--c-line);
  border-radius: var(--r-md);
  background: linear-gradient(180deg, rgba(16, 26, 51, 0.7), rgba(8, 12, 26, 0.6));
}

.sg-tabs__panel[hidden] { display: none; }
.sg-tabs__panel > *:last-child { margin-bottom: 0; }

/* ---------- 14. 星标收藏 ---------- */
.sg-star {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 12px;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--c-dust);
  border: 1px solid var(--c-line);
  border-radius: var(--r-sm);
  background: rgba(16, 26, 51, 0.5);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.sg-star::before {
  content: "☆";
  font-size: 14px;
  line-height: 1;
}

.sg-star[aria-pressed="true"] {
  color: var(--c-amber);
  border-color: rgba(255, 198, 92, 0.6);
  background: rgba(255, 198, 92, 0.1);
}

.sg-star[aria-pressed="true"]::before { content: "★"; }

/* ---------- 15. 滚动进度条 ---------- */
.sg-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  z-index: 200;
  pointer-events: none;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--c-nebula), var(--c-electric) 58%, var(--c-amber));
}

/* ---------- 16. 滚动显现 ---------- */
.sg-js [data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}

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

/* ---------- 17. 无障碍与动效偏好 ---------- */
.sg-visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

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

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

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

/* ---------- 18. 窄屏细节 ---------- */
@media (max-width: 480px) {
  :root { --header-h: 62px; }

  .sg-brand__mark { width: 28px; height: 28px; }
  .sg-brand__name { font-size: 17px; }
  .sg-burger__text { display: none; }

  .sg-footer__motto { letter-spacing: 0.24em; font-size: 13px; }
}