/* ============================================================
   cover.css — 封面：冷档案编辑风
   ============================================================ */

.view-cover {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  min-height: 100vh;
  min-height: 100dvh;
  margin: 0;
  padding: clamp(1.4rem, 4vh, 2.6rem) 1.2rem clamp(4.2rem, 9vh, 5.5rem);
  width: auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: clamp(1.25rem, 2.8vh, 2rem);
}
.view-cover::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(42, 95, 143, 0.032) 1px, transparent 1px),
    linear-gradient(90deg, rgba(42, 95, 143, 0.032) 1px, transparent 1px),
    linear-gradient(rgba(42, 95, 143, 0.065) 1px, transparent 1px),
    linear-gradient(90deg, rgba(42, 95, 143, 0.065) 1px, transparent 1px);
  background-size: 24px 24px, 24px 24px, 96px 96px, 96px 96px;
  -webkit-mask-image: linear-gradient(to bottom, rgba(0,0,0,.84), rgba(0,0,0,.36) 72%, transparent);
  mask-image: linear-gradient(to bottom, rgba(0,0,0,.84), rgba(0,0,0,.36) 72%, transparent);
}
.view-cover::after {
  content: "";
  position: absolute;
  inset: clamp(1rem, 3vw, 2rem);
  z-index: -1;
  pointer-events: none;
  border: 1px solid rgba(42, 95, 143, 0.075);
  background:
    linear-gradient(var(--accent), var(--accent)) 0 0 / 34px 1px no-repeat,
    linear-gradient(var(--accent), var(--accent)) 0 0 / 1px 34px no-repeat,
    linear-gradient(var(--accent), var(--accent)) 100% 100% / 34px 1px no-repeat,
    linear-gradient(var(--accent), var(--accent)) 100% 100% / 1px 34px no-repeat;
  opacity: 0.32;
}

body.is-cover .site-main {
  padding: 0;
  min-height: 100vh;
  min-height: 100dvh;
}
body.is-cover .atmosphere {
  opacity: 1;
}

.cover-art {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}
.art-a {
  display: block;
  width: 100%;
  height: 100%;
  max-height: none;
  opacity: 0.62;
}
.art-a .grid-minor { stroke: rgba(42, 95, 143, 0.055); stroke-width: 1; fill: none; }
.art-a .grid-major { stroke: rgba(42, 95, 143, 0.11); stroke-width: 1; fill: none; }
.art-a .grid-field { opacity: 0.7; }
.art-a .dim { stroke: rgba(20, 22, 28, 0.21); fill: none; stroke-width: 1; }
.art-a .heavy { stroke-width: 1.2; }
.art-a .hi { stroke: rgba(42, 95, 143, 0.72); fill: none; stroke-width: 1.25; }
.art-a .fill { fill: rgba(42, 95, 143, 0.055); }
.art-a .dashed { stroke-dasharray: 4 7; }
.art-a .detail { stroke: rgba(42, 95, 143, 0.18); fill: none; stroke-width: 0.8; }
.art-a .dimension { stroke: rgba(20, 22, 28, 0.24); fill: none; stroke-width: 0.8; }
.art-a .node {
  fill: var(--paper);
  stroke: rgba(42, 95, 143, 0.72);
  stroke-width: 1.2;
}
.art-a text {
  fill: rgba(20, 22, 28, 0.46);
  font-size: 10px;
  letter-spacing: 0.16em;
  font-family: var(--font-sans);
}

.cover-stage {
  position: relative;
  z-index: 2;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.95rem;
  padding: clamp(1rem, 2vw, 1.5rem);
  max-width: min(96vw, 900px);
  background: radial-gradient(ellipse at center, rgba(243, 245, 248, 0.96) 0%, rgba(243, 245, 248, 0.8) 48%, transparent 76%);
}

.cover-kicker {
  font-size: 0.81rem;
  letter-spacing: 0.5em;
  text-transform: uppercase;
  color: var(--mute);
  font-weight: 300;
}
.cover-title {
  font-weight: 300;
  font-size: clamp(3rem, 9.4vw, 6rem);
  letter-spacing: 0.16em;
  line-height: 1.08;
  color: var(--ink);
}
.cover-title .hl {
  color: var(--accent);
  -webkit-text-stroke: 0;
  text-shadow: none;
}
.cover-sub {
  font-size: 1.19rem;
  letter-spacing: 0.4em;
  color: var(--silver);
  font-weight: 300;
}
.cover-tagline {
  margin-top: 0.2rem;
  font-size: 0.9rem;
  letter-spacing: 0.16em;
  color: var(--mute);
  font-weight: 300;
}

.cover-conclusion {
  width: min(92vw, 760px);
  display: grid;
  grid-template-columns: 0.8fr 1fr 1.7fr;
  margin-top: 0.35rem;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  text-align: left;
}
.cover-conclusion-item {
  min-width: 0;
  padding: 0.72rem clamp(0.75rem, 1.8vw, 1.2rem);
}
.cover-conclusion-item + .cover-conclusion-item {
  border-left: 1px solid var(--line);
}
.cover-conclusion-label,
.cover-conclusion-value {
  display: block;
}
.cover-conclusion-label {
  margin-bottom: 0.25rem;
  font-size: 0.56rem;
  letter-spacing: 0.22em;
  color: var(--mute);
  text-transform: uppercase;
}
.cover-conclusion-value {
  font-size: clamp(0.72rem, 1vw, 0.86rem);
  line-height: 1.55;
  letter-spacing: 0.08em;
  color: var(--ink);
  font-weight: 400;
}

.cover-enter {
  display: inline-block;
  margin-top: 1.15rem;
  padding: 0.98rem 1.88rem;
  border: 1px solid var(--line);
  border-radius: 0;
  color: var(--ink);
  letter-spacing: 0.28em;
  font-size: 0.94rem;
  font-weight: 400;
  font-family: var(--font-sans);
  background: var(--paper-elev);
  transition: border-color 0.25s, background 0.25s, color 0.25s, transform 0.25s;
}
.cover-enter:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

.cover-horizon { display: none; }

/* 入场只用位移，不用 opacity——封面在 hidden 时就会渲染，
   若先以 opacity:0 开启动画，显示时会卡在透明。 */
@media (prefers-reduced-motion: no-preference) {
  .cover-kicker,
  .cover-title,
  .cover-sub,
  .cover-tagline,
  .cover-conclusion,
  .cover-enter {
    animation: coverIn 0.9s var(--ease-dive) both;
  }
  .cover-kicker    { animation-delay: 0.05s; }
  .cover-title     { animation-delay: 0.12s; }
  .cover-sub       { animation-delay: 0.2s; }
  .cover-tagline   { animation-delay: 0.28s; }
  .cover-conclusion{ animation-delay: 0.34s; }
  .cover-enter     { animation-delay: 0.4s; }
}

@keyframes coverIn {
  from { transform: translateY(12px); }
  to { transform: none; }
}

@media (max-width: 640px) {
  .view-cover { gap: 1.35rem; }
  .view-cover::before {
    background-size: 18px 18px, 18px 18px, 72px 72px, 72px 72px;
  }
  .art-a {
    opacity: 0.52;
  }
  .cover-stage { gap: 0.72rem; }
  .cover-title { font-size: clamp(2.4rem, 10vw, 3.4rem); }
  .cover-tagline {
    max-width: 28em;
    line-height: 1.7;
  }
  .cover-conclusion {
    grid-template-columns: 1fr 1fr;
  }
  .cover-conclusion-item {
    padding: 0.62rem 0.68rem;
  }
  .cover-conclusion-item:nth-child(3) {
    grid-column: 1 / -1;
    border-top: 1px solid var(--line);
    border-left: 0;
  }
  .cover-enter {
    margin-top: 0.8rem;
    padding: 0.9rem 1.6rem;
    font-size: 0.85rem;
  }
}