/* ============================================================
   layout.css — 外壳 / 顶栏 / 区块骨架 / 开场
   ============================================================ */

.wrap {
  width: 100%;
  padding-inline: var(--gutter);
  margin-inline: auto;
  max-width: 2000px;
}

.section {
  position: relative;
  padding-block: clamp(72px, 11vh, 150px);
}

.section + .section { padding-top: clamp(56px, 9vh, 120px); }

/* ---------------------------------------------- 顶栏 */

.topbar {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 90;
  height: var(--topbar-h);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 24px;
  padding-inline: var(--gutter);
  background: color-mix(in srgb, var(--paper) 78%, transparent);
  backdrop-filter: saturate(150%) blur(14px);
  -webkit-backdrop-filter: saturate(150%) blur(14px);
  border-bottom: 1px solid transparent;
  transform: translate3d(0, -100%, 0);
  transition: transform .55s var(--e-out), border-color .3s linear, background-color .3s linear;
  will-change: transform;
}

.topbar.is-visible { transform: translate3d(0, 0, 0); }
.topbar.is-stuck { border-bottom-color: var(--line); }

.topbar__mark {
  display: inline-flex;
  align-items: baseline;
  font-weight: 900;
  font-size: 17px;
  letter-spacing: -0.05em;
}

.topbar__markDot { color: var(--signal); }

.topbar__nav {
  display: flex;
  justify-content: center;
  gap: clamp(12px, 1.9vw, 34px);
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.topbar__nav a {
  position: relative;
  padding-block: 4px;
  white-space: nowrap;
  color: var(--ink-70);
  transition: color .25s var(--e-soft);
}

.topbar__nav a i {
  font-style: normal;
  font-size: 10px;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--muted);
  opacity: .55;
  margin-left: 3px;
}

.topbar__nav a::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 1.5px;
  background: var(--signal);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform .4s var(--e-out);
}

.topbar__nav a:hover,
.topbar__nav a.is-active { color: var(--ink); }
.topbar__nav a:hover::after,
.topbar__nav a.is-active::after { transform: scaleX(1); }

.topbar__side {
  display: flex;
  align-items: center;
  gap: 10px;
}

.topbar__progress {
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 1.5px;
  background: transparent;
  pointer-events: none;
}

.topbar__progress span {
  display: block;
  height: 100%;
  width: 100%;
  background: var(--signal);
  transform: scaleX(var(--p, 0));
  transform-origin: left;
}

/* ---------------------------------------------- 幽灵按钮 */

.ghostbtn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 32px;
  padding-inline: 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 11.5px;
  font-weight: 750;
  letter-spacing: .02em;
  white-space: nowrap;
  transition: border-color .25s, background-color .25s, color .25s, transform .3s var(--e-out);
}

.ghostbtn:hover { border-color: var(--ink); transform: translateY(-1px); }

.ghostbtn--solid {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}

.ghostbtn--solid:hover { background: var(--signal); border-color: var(--signal); color: #fff; }

.ghostbtn__track {
  position: relative;
  width: 26px; height: 14px;
  border-radius: 999px;
  background: var(--ink);
  flex: none;
}

.ghostbtn__thumb {
  position: absolute;
  top: 3px; left: 3px;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--paper);
  transition: transform .35s var(--e-out);
}

[data-theme="dark"] .ghostbtn__thumb { transform: translateX(12px); }

/* ---------------------------------------------- 区块标题 */

.secthead { margin-bottom: clamp(26px, 4vw, 56px); }

.secthead--row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(240px, 34%);
  align-items: end;
  gap: clamp(20px, 4vw, 60px);
}

.secthead__no {
  display: block;
  font-family: "SFMono-Regular", ui-monospace, Consolas, monospace;
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--signal);
  margin-bottom: 10px;
}

.secthead__title {
  font-weight: 900;
  font-size: clamp(38px, 7.4vw, 118px);
  letter-spacing: -0.058em;
  line-height: .86;
}

.secthead__title em {
  display: block;
  margin-top: 12px;
  font-size: clamp(12px, 1.15vw, 17px);
  font-weight: 650;
  letter-spacing: .01em;
  color: var(--muted);
}

.secthead__sub {
  margin-top: 14px;
  font-size: 13.5px;
  color: var(--muted);
  max-width: 52ch;
}

.secthead__aside {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 16px;
  padding-bottom: 6px;
}

.secthead__aside p {
  font-size: 13.5px;
  line-height: 1.72;
  color: var(--muted);
  max-width: 44ch;
}

/* ---------------------------------------------- 开场 */

.opening {
  position: relative;
  height: 220vh;
  background: #08080A;
}

.opening__stage {
  position: sticky;
  top: 0;
  height: 100svh;
  overflow: hidden;
  background: #08080A;
  isolation: isolate;
}

.opening__canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
}

.opening__scrim {
  position: absolute;
  inset: 0;
  z-index: 2;
  pointer-events: none;
  background:
    radial-gradient(120% 90% at 50% 8%, transparent 40%, rgba(0,0,0,.55) 100%),
    linear-gradient(180deg, rgba(0,0,0,.55) 0%, transparent 26%, transparent 58%, rgba(0,0,0,.72) 100%);
}

.opening__ui {
  position: absolute;
  z-index: 3;
  left: var(--gutter);
  right: var(--gutter);
  top: 50%;
  transform: translate3d(0, calc(-50% + var(--shift, 0px)), 0);
  color: #fff;
  opacity: var(--fade, 1);
  will-change: transform, opacity;
}

.opening__eyebrow {
  font-family: "SFMono-Regular", ui-monospace, Consolas, monospace;
  font-size: 10.5px;
  letter-spacing: .26em;
  text-transform: uppercase;
  opacity: .82;
  margin-bottom: clamp(14px, 2.4vw, 26px);
}

.opening__title {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  font-weight: 900;
  font-size: clamp(58px, 15.5vw, 250px);
  letter-spacing: -0.072em;
  line-height: .8;
}

.opening__dot { color: var(--signal); }

.opening__meta {
  margin-top: clamp(18px, 3vw, 34px);
  display: grid;
  gap: 6px;
  max-width: 70ch;
}

.opening__meta p:first-child {
  font-size: clamp(16px, 1.9vw, 26px);
  font-weight: 750;
  letter-spacing: -0.02em;
}

.opening__meta p:last-child {
  font-size: clamp(11.5px, 1.05vw, 14px);
  opacity: .68;
  letter-spacing: .005em;
}

.opening__foot {
  position: absolute;
  z-index: 3;
  left: var(--gutter);
  right: var(--gutter);
  bottom: clamp(30px, 5vh, 56px);
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  color: #fff;
  font-family: "SFMono-Regular", ui-monospace, Consolas, monospace;
  font-size: 10px;
  letter-spacing: .2em;
  opacity: .8;
}

.opening__scroll { display: flex; align-items: center; gap: 10px; }

.opening__scroll span {
  display: block;
  width: 34px; height: 1px;
  background: currentColor;
  position: relative;
  overflow: hidden;
}

.opening__scroll span::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--signal);
  transform: translateX(-100%);
  animation: slide 2.4s var(--e-soft) infinite;
}

@keyframes slide {
  0%   { transform: translateX(-100%); }
  55%  { transform: translateX(0); }
  100% { transform: translateX(100%); }
}

.opening__counter b { font-weight: 700; color: var(--signal); }

.opening__bar {
  position: absolute;
  z-index: 3;
  left: 0; right: 0; bottom: 0;
  height: 2px;
  background: rgba(255,255,255,.14);
}

.opening__bar span {
  display: block;
  height: 100%;
  width: 100%;
  background: var(--signal);
  transform: scaleX(var(--p, 0));
  transform-origin: left;
}

/* ---------------------------------------------- 页脚 */

.foot {
  margin-top: clamp(60px, 10vh, 120px);
  padding: 22px var(--gutter);
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: space-between;
  font-size: 11.5px;
  color: var(--muted);
}

.foot a:hover { color: var(--signal); }

/* ---------------------------------------------- 响应式骨架 */

@media (max-width: 1080px) {
  .topbar { grid-template-columns: auto 1fr; }
  .topbar__nav { display: none; }
  .secthead--row { grid-template-columns: 1fr; align-items: start; }
}

@media (max-width: 720px) {
  :root { --topbar-h: 54px; }
  .opening { height: 180vh; }
  .topbar__side .ghostbtn span:not(.ghostbtn__track) { display: none; }
  .ghostbtn--solid span { display: inline !important; }
  .foot { flex-direction: column; }
}