/* ─────────────────────────────────────────────
   echo.css · 殘響扉頁
   章節目錄式設計（與 milestone.html 同調但不同氣質）：
   milestone 是「時間軸 · 走過的路」
   echo     是「目錄 · 收下的迴響」
   ───────────────────────────────────────────── */

body {
  background: var(--vas-void);
  color: var(--vas-ash-0);
  font-family: var(--vas-serif);
  min-height: 100vh;
}

main {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 48px;
}

/* ─── 扉頁 ─── */
.echo-head {
  padding: 96px 0 56px;
  border-bottom: 1px solid var(--vas-rule);
}

.echo-kicker {
  font-family: var(--vas-mono);
  font-size: 10px;
  letter-spacing: 0.22em;
  color: var(--vas-ash-3);
  text-transform: uppercase;
  margin-bottom: 32px;
}

.echo-title {
  font-family: var(--vas-serif);
  font-weight: 300;
  font-size: clamp(36px, 5vw, 56px);
  line-height: 1.25;
  letter-spacing: -0.01em;
  color: var(--vas-ash-0);
  margin: 0 0 36px;
  max-width: 22ch;
}
.echo-title em {
  font-style: normal;
  font-weight: 500;
  background: linear-gradient(180deg, transparent 64%, rgba(196, 113, 245, 0.22) 64%);
  padding: 0 0.08em;
}

.echo-lede {
  font-family: var(--vas-serif);
  font-size: 18px;
  line-height: 1.85;
  color: var(--vas-ash-2);
  max-width: 38ch;
}
.echo-lede p {
  margin: 0 0 1em;
}
.echo-lede p:last-child {
  margin-bottom: 0;
}
.echo-lede em {
  font-style: normal;
  font-weight: 500;
  background: linear-gradient(180deg, transparent 64%, rgba(196, 113, 245, 0.22) 64%);
  padding: 0 0.08em;
  color: var(--vas-ash-1);
}

/* ─── 題辭 · 開場引言 ─── */
.echo-epigraph {
  font-family: var(--vas-serif);
  font-weight: 400;
  font-size: 19px;
  letter-spacing: 0.22em;
  color: var(--vas-ash-1);
  margin: 0 0 1.6em !important;
  padding-left: 1.5em;
  border-left: 1px solid var(--vas-rule);
  font-style: italic;
}

.echo-meta {
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--vas-rule);
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  font-family: var(--vas-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--vas-ash-3);
}
.echo-meta strong {
  display: block;
  font-family: var(--vas-serif);
  font-weight: 500;
  font-size: 22px;
  letter-spacing: -0.01em;
  color: var(--vas-ash-0);
  text-transform: none;
  margin-top: 8px;
}

/* ─── 目錄 · TOC ─── */
.echo-toc {
  padding: 80px 0 40px;
}

.echo-toc-label {
  font-family: var(--vas-mono);
  font-size: 10px;
  letter-spacing: 0.24em;
  color: var(--vas-ash-3);
  text-transform: uppercase;
  margin-bottom: 32px;
}

.echo-toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.echo-toc-list li {
  border-top: 1px solid var(--vas-rule);
}
.echo-toc-list li:last-child {
  border-bottom: 1px solid var(--vas-rule);
}

.echo-toc-item {
  display: grid;
  grid-template-columns: 96px 1fr 64px;
  align-items: start;
  gap: 32px;
  padding: 36px 8px;
  text-decoration: none;
  color: inherit;
  transition: background .4s;
  position: relative;
}
.echo-toc-item::before {
  content: '';
  position: absolute;
  left: 0; top: -1px;
  width: 0; height: 1px;
  background: var(--vas-aurora-violet);
  transition: width .6s cubic-bezier(.2, .8, .2, 1);
}
.echo-toc-item:hover::before,
.echo-toc-item:focus-visible::before {
  width: 100%;
}
.echo-toc-item:hover {
  background: rgba(240, 232, 220, 0.02);
}

.echo-toc-no {
  font-family: var(--vas-serif);
  font-weight: 300;
  font-size: 22px;
  color: var(--vas-aurora-violet);
  letter-spacing: 0.04em;
  padding-top: 4px;
}

.echo-toc-body {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.echo-toc-head {
  display: flex;
  align-items: baseline;
  gap: 18px;
}

.echo-toc-name {
  font-family: var(--vas-serif);
  font-weight: 500;
  font-size: 26px;
  color: var(--vas-ash-0);
  margin: 0;
  letter-spacing: 0.02em;
  transition: transform .4s cubic-bezier(.2, .8, .2, 1);
}
.echo-toc-item:hover .echo-toc-name {
  transform: translateX(3px);
}

.echo-toc-kicker {
  font-family: var(--vas-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  color: var(--vas-ash-3);
  text-transform: uppercase;
}

.echo-toc-desc {
  font-family: var(--vas-serif);
  font-size: 15px;
  line-height: 1.75;
  color: var(--vas-ash-2);
  margin: 0;
  max-width: 52ch;
}

.echo-toc-go {
  font-family: var(--vas-serif);
  font-size: 22px;
  color: var(--vas-aurora-violet);
  text-align: right;
  padding-top: 4px;
  opacity: 0.4;
  transition: opacity .3s, transform .3s;
}
.echo-toc-item:hover .echo-toc-go {
  opacity: 0.95;
  transform: translateX(4px);
}

/* ─── 待補狀態（is-pending） ─── */
.echo-toc-item.is-pending {
  cursor: default;
}
.echo-toc-item.is-pending:hover {
  background: transparent;
}
.echo-toc-item.is-pending::before {
  display: none;
}
.echo-toc-item.is-pending .echo-toc-no,
.echo-toc-item.is-pending .echo-toc-name,
.echo-toc-item.is-pending .echo-toc-desc {
  color: var(--vas-ash-3);
}
.echo-toc-item.is-pending .echo-toc-no {
  color: var(--vas-ash-3);
}
.echo-toc-go.is-pending-mark {
  font-family: var(--vas-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--vas-ash-3);
  opacity: 0.6;
}

/* ─── 迴響 · 邀請段 ─── */
.echo-reverb {
  padding: 80px 0 96px;
  border-top: 1px solid var(--vas-rule);
  text-align: center;
}

.echo-reverb-text {
  font-family: var(--vas-serif);
  font-weight: 300;
  font-size: clamp(22px, 3vw, 28px);
  color: var(--vas-ash-1);
  margin: 0 0 24px;
  letter-spacing: 0.02em;
}

.echo-reverb-link {
  font-family: var(--vas-mono);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--vas-aurora-violet);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: letter-spacing .3s, opacity .3s;
}
.echo-reverb-link:hover,
.echo-reverb-link:focus-visible {
  letter-spacing: 0.2em;
}
.echo-reverb-arrow {
  font-family: var(--vas-serif);
  font-size: 18px;
  animation: echo-reverb-breathe 3.5s ease-in-out infinite;
}
@keyframes echo-reverb-breathe {
  0%, 100% { opacity: 0.3; }
  50%      { opacity: 0.9; }
}
.echo-reverb-link:hover .echo-reverb-arrow {
  animation-play-state: paused;
  opacity: 0.95;
}
@media (prefers-reduced-motion: reduce) {
  .echo-reverb-arrow { animation: none; opacity: 0.5; }
}

/* ─── 響應式 ─── */
@media (max-width: 820px) {
  main {
    padding: 0 24px;
  }
  .echo-head {
    padding: 56px 0 32px;
  }
  .echo-meta {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .echo-toc {
    padding: 56px 0 24px;
  }
  .echo-toc-item {
    grid-template-columns: 64px 1fr;
    grid-template-rows: auto auto;
    gap: 16px 20px;
    padding: 28px 4px;
  }
  .echo-toc-no {
    font-size: 18px;
    padding-top: 6px;
  }
  .echo-toc-name {
    font-size: 22px;
  }
  .echo-toc-go {
    grid-column: 2;
    grid-row: 2;
    text-align: left;
    padding-top: 0;
  }
  .echo-toc-go.is-pending-mark {
    font-size: 10px;
  }
  .echo-reverb {
    padding: 56px 0 72px;
  }
}