/* K2 · 全幅居中横幅 + 交替叙事 · Signal */
:root {
  --ink: #122033;
  --muted: #5a6b7d;
  --line: #d7e0ea;
  --teal: #0f766e;
  --teal-deep: #115e59;
  --sand: #f4f7fa;
  --white: #fff;
  --fd: "Sora", "Segoe UI", sans-serif;
  --fb: "IBM Plex Sans", "Segoe UI", sans-serif;
  --max: 1080px;
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
.zc90e4body {
  margin: 0; font-family: var(--fb); color: var(--ink);
  background: var(--sand); line-height: 1.65; overflow-x: hidden;
}
img { max-width: 100%; display: block; height: auto; }
a { color: inherit; text-decoration: none; }
.zc90e4container { width: min(100% - 2rem, var(--max)); margin-inline: auto; }

.zc90e4header {
  position: sticky; top: 0; z-index: 50; background: rgba(244, 247, 250, 0.94);
  border-bottom: 1px solid var(--line); backdrop-filter: blur(10px);
}
.zc90e4bar { min-height: 64px; display: flex; align-items: center; gap: 1rem; }
.zc90e4logo { font-family: var(--fd); font-weight: 700; font-size: 1.1rem; color: var(--teal-deep); }
.zc90e4menu { margin-left: auto; display: flex; flex-wrap: wrap; gap: 0.35rem 0.9rem; font-size: 0.92rem; font-weight: 500; color: var(--muted); }
.zc90e4menu a:hover { color: var(--teal); }
.zc90e4menu_btn {
  display: none; margin-left: auto; border: 1px solid var(--line); background: var(--white);
  width: 40px; height: 40px; border-radius: 8px; cursor: pointer;
}

.zc90e4banner {
  position: relative; min-height: min(78vh, 640px);
  display: grid; place-items: center; color: #fff; overflow: hidden;
}
.zc90e4banner_media, .zc90e4banner_shade { position: absolute; inset: 0; }
.zc90e4banner_media img { width: 100%; height: 100%; object-fit: cover; }
.zc90e4banner_shade {
  background:
    linear-gradient(180deg, rgba(18, 32, 51, 0.55) 0%, rgba(15, 118, 110, 0.72) 100%);
}
.zc90e4banner_center {
  position: relative; z-index: 1; text-align: center; padding: 4.5rem 0;
  max-width: 46rem; margin-inline: auto;
}
.zc90e4banner_kicker {
  display: inline-block; margin: 0 0 0.9rem; padding: 0.35rem 0.8rem;
  border: 1px solid rgba(255,255,255,0.35); border-radius: 999px; font-size: 0.82rem; letter-spacing: 0.06em;
}
.zc90e4banner h1 {
  margin: 0 0 1rem; font-family: var(--fd); font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.15; letter-spacing: -0.02em;
}
.zc90e4banner_desc { margin: 0 auto 1.6rem; opacity: 0.92; font-size: 1.05rem; }
.zc90e4banner_cta { display: flex; justify-content: center; flex-wrap: wrap; gap: 0.75rem; }

.zc90e4btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 0.8rem 1.25rem; border-radius: 10px; font-weight: 600; border: 1px solid transparent;
}
.zc90e4btn_solid { background: var(--teal); color: #fff; }
.zc90e4btn_solid:hover { background: var(--teal-deep); }
.zc90e4btn_line { border-color: rgba(255,255,255,0.55); color: #fff; }
.zc90e4banner .zc90e4btn_line:hover { background: rgba(255,255,255,0.12); }

.zc90e4ad { padding: 0.85rem 0; }
.zc90e4block { padding: 4rem 0; }
.zc90e4alt { background: var(--white); }
.zc90e4block_head { margin-bottom: 2rem; max-width: 38rem; }
.zc90e4block_head.zc90e4center { margin-inline: auto; text-align: center; }
.zc90e4block_head h2 {
  margin: 0 0 0.6rem; font-family: var(--fd); font-size: clamp(1.55rem, 3vw, 2.1rem);
}
.zc90e4block_head p { margin: 0; color: var(--muted); }

.zc90e4platform_bar {
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 0.75rem;
}
.zc90e4platform {
  background: var(--white); border: 1px solid var(--line); border-radius: 12px;
  padding: 1.1rem 0.9rem; text-align: center; transition: 0.2s ease;
}
.zc90e4platform:hover { border-color: var(--teal); transform: translateY(-2px); }
.zc90e4platform strong { display: block; font-family: var(--fd); margin-bottom: 0.25rem; }
.zc90e4platform span { color: var(--muted); font-size: 0.85rem; }
.zc90e4tip { margin: 1rem 0 0; color: var(--muted); font-size: 0.92rem; text-align: center; }

.zc90e4zig {
  display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; align-items: center; margin-bottom: 2.5rem;
}
.zc90e4zig_rev .zc90e4zig_media { order: 2; }
.zc90e4zig_rev .zc90e4zig_copy { order: 1; }
.zc90e4zig_media {
  border-radius: 16px; overflow: hidden; border: 1px solid var(--line); background: var(--sand);
}
.zc90e4zig_media img { width: 100%; aspect-ratio: 16/10; object-fit: cover; }
.zc90e4zig_copy h3 { margin: 0 0 0.6rem; font-family: var(--fd); font-size: 1.35rem; }
.zc90e4zig_copy p { margin: 0; color: var(--muted); }

.zc90e4timeline_wrap { max-width: 720px; }
.zc90e4timeline {
  list-style: none; margin: 0; padding: 0; border-left: 2px solid var(--line);
}
.zc90e4timeline li {
  position: relative; padding: 0 0 1.75rem 1.5rem;
}
.zc90e4timeline li::before {
  content: ""; position: absolute; left: -7px; top: 0.35rem; width: 12px; height: 12px;
  border-radius: 50%; background: var(--teal); border: 2px solid var(--white);
}
.zc90e4timeline h3 { margin: 0 0 0.35rem; font-family: var(--fd); font-size: 1.1rem; }
.zc90e4timeline p { margin: 0; color: var(--muted); }

.zc90e4official { background: linear-gradient(135deg, #115e59, #0f766e); color: #fff; }
.zc90e4official_box {
  display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 2rem; align-items: center;
}
.zc90e4official h2 { margin: 0 0 0.75rem; font-family: var(--fd); font-size: clamp(1.5rem, 3vw, 2rem); }
.zc90e4official p { margin: 0 0 1.25rem; opacity: 0.92; }
.zc90e4official .zc90e4btn_solid { background: #fff; color: var(--teal-deep); }
.zc90e4official_list { margin: 0; padding: 0; list-style: none; display: grid; gap: 0.65rem; }
.zc90e4official_list li {
  padding: 0.75rem 1rem; border: 1px solid rgba(255,255,255,0.28); border-radius: 10px;
}

.zc90e4faq_grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.zc90e4faq_grid article {
  background: var(--sand); border: 1px solid var(--line); border-radius: 12px; padding: 1.25rem;
}
.zc90e4faq_grid h3 { margin: 0 0 0.45rem; font-family: var(--fd); font-size: 1.05rem; }
.zc90e4faq_grid p { margin: 0; color: var(--muted); font-size: 0.95rem; }

.zc90e4cta { padding: 3.5rem 0 4rem; }
.zc90e4cta_inner {
  text-align: center; background: var(--white); border: 1px solid var(--line);
  border-radius: 18px; padding: 2.5rem 1.25rem;
}
.zc90e4cta_inner h2 { margin: 0 0 0.5rem; font-family: var(--fd); }
.zc90e4cta_inner p { margin: 0 0 1.2rem; color: var(--muted); }

.zc90e4footer { background: #122033; color: rgba(255,255,255,0.8); padding: 2.75rem 0 2rem; }
.zc90e4flink h3 { margin: 0 0 0.6rem; color: #fff; font-size: 1rem; }
.zc90e4flink ul { list-style: none; margin: 0 0 1.25rem; padding: 0; display: flex; flex-wrap: wrap; gap: 0.5rem 1rem; }
.zc90e4flink a:hover { color: #fff; }
.zc90e4footer_brand { font-family: var(--fd); font-weight: 700; color: #fff; margin: 0.5rem 0; }
.zc90e4footer_note { margin: 0 0 1rem; max-width: 40rem; }
.zc90e4powered { font-size: 0.88rem; opacity: 0.75; }
.zc90e4powered a { color: #fff; }

@media (max-width: 900px) {
  .zc90e4platform_bar { grid-template-columns: repeat(3, 1fr); }
  .zc90e4zig, .zc90e4zig_rev .zc90e4zig_media, .zc90e4zig_rev .zc90e4zig_copy,
  .zc90e4official_box, .zc90e4faq_grid { grid-template-columns: 1fr; }
  .zc90e4zig_rev .zc90e4zig_media, .zc90e4zig_rev .zc90e4zig_copy { order: initial; }
}
@media (max-width: 720px) {
  .zc90e4menu_btn { display: inline-flex; align-items: center; justify-content: center; }
  .zc90e4menu {
    display: none; position: absolute; left: 0; right: 0; top: 64px;
    background: #fff; border-bottom: 1px solid var(--line); padding: 0.85rem 1rem; flex-direction: column;
  }
  .zc90e4menu.is-open { display: flex; }
  .zc90e4header { position: sticky; }
  .zc90e4bar { position: relative; }
  .zc90e4platform_bar { grid-template-columns: 1fr 1fr; }
  .zc90e4banner { min-height: 520px; }
}