/**
 * 北辞弱网官方站样式
 * 独立视觉体系：信号网格 + 钢青冷调，不与同目录其他项目共用模板
 */

:root {
  --ink: #0c1520;
  --ink-soft: #243447;
  --mute: #5a6b7d;
  --paper: #f3f6f9;
  --panel: #ffffff;
  --line: rgba(12, 21, 32, 0.1);
  --signal: #0d8f9a;
  --signal-deep: #066873;
  --signal-soft: #d6f1f3;
  --accent: #1f6feb;
  --warn: #c45c26;
  --shadow: 0 18px 50px rgba(12, 21, 32, 0.1);
  --radius: 18px;
  --shell: min(1120px, calc(100% - 2.4rem));
  --font-display: "Sora", "Noto Sans SC", sans-serif;
  --font-body: "Noto Sans SC", "Sora", sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--font-body);
  background:
    radial-gradient(1200px 520px at 8% -10%, rgba(13, 143, 154, 0.14), transparent 60%),
    radial-gradient(900px 480px at 100% 8%, rgba(31, 111, 235, 0.1), transparent 55%),
    linear-gradient(180deg, #e8eef4 0%, var(--paper) 28%, #eef3f7 100%);
  line-height: 1.65;
  overflow-x: hidden;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: inherit;
  text-decoration: none;
}

.shell {
  width: var(--shell);
  margin-inline: auto;
}

.skip {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--ink);
  color: #fff;
  padding: 0.6rem 1rem;
  z-index: 100;
}

.skip:focus {
  left: 0.8rem;
  top: 0.8rem;
}

/* —— 顶栏 —— */
.mast {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(14px);
  background: rgba(243, 246, 249, 0.82);
  border-bottom: 1px solid transparent;
  transition: border-color 0.25s ease, background 0.25s ease;
}

.mast.is-solid {
  border-bottom-color: var(--line);
  background: rgba(255, 255, 255, 0.92);
}

.mast-inner {
  display: flex;
  align-items: center;
  gap: 1rem;
  min-height: 68px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: 0.02em;
}

.brand img {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  object-fit: cover;
  box-shadow: 0 0 0 2px rgba(13, 143, 154, 0.25);
}

.nav {
  display: flex;
  gap: 1.35rem;
  margin-left: auto;
  font-size: 0.95rem;
  color: var(--ink-soft);
}

.nav a {
  position: relative;
  padding: 0.2rem 0;
}

.nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 100%;
  bottom: -2px;
  height: 2px;
  background: var(--signal);
  transition: right 0.25s ease;
}

.nav a:hover::after,
.nav a:focus-visible::after {
  right: 0;
}

.mast-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-left: 0.4rem;
  padding: 0.55rem 1.05rem;
  border-radius: 999px;
  background: var(--ink);
  color: #fff;
  font-size: 0.9rem;
  font-weight: 600;
  transition: transform 0.2s ease, background 0.2s ease;
}

.mast-cta:hover {
  background: var(--signal-deep);
  transform: translateY(-1px);
}

.burger {
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  cursor: pointer;
  margin-left: auto;
  padding: 0;
}

.burger span {
  display: block;
  width: 18px;
  height: 2px;
  margin: 5px auto;
  background: var(--ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.burger[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.burger[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.burger[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* —— 首屏 —— */
.hero {
  position: relative;
  min-height: min(92vh, 860px);
  display: grid;
  align-items: end;
  overflow: hidden;
  isolation: isolate;
}

.hero-plane {
  position: absolute;
  inset: 0;
  z-index: -2;
  background:
    linear-gradient(115deg, rgba(8, 28, 42, 0.88) 0%, rgba(8, 42, 48, 0.72) 48%, rgba(12, 36, 58, 0.55) 100%),
    url("../logo.png") center 28% / cover no-repeat;
  transform: scale(1.04);
  animation: heroDrift 18s ease-in-out infinite alternate;
}

.hero-mesh {
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(rgba(214, 241, 243, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(214, 241, 243, 0.08) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: linear-gradient(180deg, #000 35%, transparent 95%);
  animation: meshPulse 10s ease-in-out infinite;
}

.hero-core {
  width: var(--shell);
  margin: 0 auto 4.8rem;
  color: #f5fafb;
  max-width: 720px;
}

.hero-brand {
  margin: 0 0 0.85rem;
  font-family: var(--font-display);
  font-size: clamp(2.6rem, 7vw, 4.4rem);
  font-weight: 700;
  letter-spacing: 0.04em;
  line-height: 1.1;
  text-shadow: 0 10px 40px rgba(0, 0, 0, 0.35);
}

.hero-lead {
  margin: 0 0 1.6rem;
  font-size: clamp(1.05rem, 2.4vw, 1.25rem);
  color: rgba(245, 250, 251, 0.88);
  max-width: 28em;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  align-items: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  min-height: 52px;
  padding: 0.8rem 1.45rem;
  border-radius: 14px;
  font-weight: 650;
  font-size: 1rem;
  border: 1px solid transparent;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.btn-primary {
  background: linear-gradient(135deg, var(--signal) 0%, #12b4a8 100%);
  color: #041518;
  box-shadow: 0 12px 30px rgba(13, 143, 154, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 16px 36px rgba(13, 143, 154, 0.45);
}

.btn-ghost {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.28);
  color: #fff;
  backdrop-filter: blur(8px);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.18);
  transform: translateY(-2px);
}

.btn-ink {
  background: var(--ink);
  color: #fff;
}

.btn-ink:hover {
  background: var(--signal-deep);
  transform: translateY(-2px);
}

.rise {
  opacity: 0;
  transform: translateY(18px);
  animation: riseIn 0.8s ease forwards;
}

.d1 { animation-delay: 0.12s; }
.d2 { animation-delay: 0.24s; }
.d3 { animation-delay: 0.36s; }

/* —— 通用区块 —— */
.block {
  padding: 5.2rem 0;
}

.block-head {
  max-width: 40rem;
  margin-bottom: 2.4rem;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 0.55rem;
  color: var(--signal-deep);
  font-family: var(--font-display);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.block-head h2 {
  margin: 0 0 0.7rem;
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 3.5vw, 2.35rem);
  line-height: 1.25;
  letter-spacing: 0.01em;
}

.block-head p {
  margin: 0;
  color: var(--mute);
  font-size: 1.05rem;
}

/* —— 信任条 —— */
.trust {
  margin-top: -2.2rem;
  position: relative;
  z-index: 2;
}

.trust-rail {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.trust-item {
  background: var(--panel);
  padding: 1.25rem 1.1rem;
  text-align: center;
}

.trust-item strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.15rem;
  margin-bottom: 0.2rem;
}

.trust-item span {
  color: var(--mute);
  font-size: 0.88rem;
}

/* —— 能力 —— */
.ability-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 1.4rem;
  align-items: stretch;
}

.ability-main {
  position: relative;
  padding: 2rem;
  border-radius: 22px;
  background:
    linear-gradient(145deg, rgba(13, 143, 154, 0.12), transparent 55%),
    var(--panel);
  border: 1px solid var(--line);
  overflow: hidden;
}

.ability-main::before {
  content: "";
  position: absolute;
  width: 220px;
  height: 220px;
  right: -60px;
  top: -70px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(31, 111, 235, 0.18), transparent 70%);
  pointer-events: none;
}

.ability-main h3,
.ability-side h3 {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 1.35rem;
}

.ability-main p,
.ability-side p {
  margin: 0;
  color: var(--mute);
}

.param-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.85rem;
  margin: 1.5rem 0 0;
  padding: 0;
  list-style: none;
}

.param-list li {
  padding: 0.95rem 1rem;
  border-radius: 14px;
  background: rgba(12, 21, 32, 0.03);
  border: 1px solid var(--line);
}

.param-list strong {
  display: block;
  margin-bottom: 0.2rem;
  font-size: 0.98rem;
}

.param-list span {
  color: var(--mute);
  font-size: 0.86rem;
}

.ability-side {
  display: grid;
  gap: 1rem;
}

.side-tile {
  padding: 1.45rem 1.35rem;
  border-radius: 18px;
  background: var(--panel);
  border: 1px solid var(--line);
}

.side-tile.accent {
  background: linear-gradient(160deg, #0b3a42 0%, #0f2a3a 100%);
  color: #eef8f9;
  border-color: transparent;
}

.side-tile.accent p {
  color: rgba(238, 248, 249, 0.78);
}

/* —— 界面展示 —— */
.shots {
  --shot-gap: 1.35rem;
  --shot-visible: 4;
  background:
    linear-gradient(180deg, transparent, rgba(13, 143, 154, 0.05) 20%, transparent 80%);
  overflow: hidden;
}

.shot-scroller {
  width: 100%;
  container-type: inline-size;
  container-name: shotbox;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scroll-snap-type: x mandatory;
  scroll-padding-inline: 0;
  padding: 1.8rem 0 1.2rem;
  outline: none;
  scrollbar-width: thin;
  scrollbar-color: rgba(13, 143, 154, 0.45) transparent;
}

.shot-scroller:focus-visible {
  box-shadow: 0 0 0 2px rgba(13, 143, 154, 0.35);
  border-radius: 8px;
}

.shot-scroller::-webkit-scrollbar {
  height: 6px;
}

.shot-scroller::-webkit-scrollbar-thumb {
  background: rgba(13, 143, 154, 0.4);
  border-radius: 999px;
}

.shot-track {
  display: flex;
  align-items: flex-start;
  flex-wrap: nowrap;
  gap: var(--shot-gap);
  width: max-content;
  padding-right: 0.5rem;
  padding-bottom: 1.6rem;
}

.shot {
  --wave: 0px;
  --bezel: 3px;
  --shot-w: 255px;
  --shot-w: calc(
    (100cqi - var(--shot-gap) * (var(--shot-visible) - 1)) / var(--shot-visible)
  );
  --shot-h: calc(var(--shot-w) * 1.72);
  margin: 0;
  width: var(--shot-w);
  flex: 0 0 var(--shot-w);
  text-align: center;
  scroll-snap-align: start;
  opacity: 0;
  transform: translateY(calc(var(--wave) + 18px));
  transition: transform 0.45s ease, opacity 0.45s ease;
}

.shot:nth-child(4n + 1) { --wave: 40px; }
.shot:nth-child(4n + 2) { --wave: 0px; }
.shot:nth-child(4n + 3) { --wave: 48px; }
.shot:nth-child(4n + 4) { --wave: 12px; }

.shot.is-in {
  opacity: 1;
  transform: translateY(var(--wave));
}

.phone {
  position: relative;
  width: 100%;
  padding: var(--bezel);
  border-radius: 16px;
  background: #15202b;
  box-shadow:
    0 14px 34px rgba(12, 21, 32, 0.14),
    inset 0 0 0 1px rgba(255, 255, 255, 0.06);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.shot:hover .phone {
  transform: translateY(-5px);
  box-shadow:
    0 20px 40px rgba(12, 21, 32, 0.16),
    inset 0 0 0 1px rgba(255, 255, 255, 0.1);
}

.phone::before {
  content: "";
  position: absolute;
  top: 7px;
  left: 50%;
  z-index: 1;
  width: 36px;
  height: 3px;
  border-radius: 999px;
  background: rgba(0, 0, 0, 0.22);
  transform: translateX(-50%);
  pointer-events: none;
}

.phone img {
  display: block;
  width: 100%;
  height: var(--shot-h);
  object-fit: cover;
  object-position: top center;
  border-radius: 13px;
  background: #e8eef4;
}

.shot figcaption {
  margin-top: 0.8rem;
  font-size: 0.9rem;
  color: var(--ink-soft);
  font-weight: 500;
}

/* —— 流程 —— */
.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  counter-reset: step;
}

.step {
  position: relative;
  padding: 1.4rem 1.2rem 1.5rem;
  border-radius: 18px;
  background: var(--panel);
  border: 1px solid var(--line);
}

.step::before {
  counter-increment: step;
  content: counter(step, decimal-leading-zero);
  display: block;
  margin-bottom: 0.85rem;
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--signal);
  letter-spacing: 0.04em;
}

.step h3 {
  margin: 0 0 0.45rem;
  font-size: 1.05rem;
}

.step p {
  margin: 0;
  color: var(--mute);
  font-size: 0.92rem;
}

/* —— FAQ —— */
.faq-list {
  display: grid;
  gap: 0.75rem;
  max-width: 820px;
}

.faq-item {
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--panel);
  overflow: hidden;
}

.faq-item summary {
  cursor: pointer;
  list-style: none;
  padding: 1.05rem 1.2rem;
  font-weight: 600;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  font-family: var(--font-display);
  font-size: 1.2rem;
  color: var(--signal-deep);
}

.faq-item[open] summary::after {
  content: "–";
}

.faq-item p {
  margin: 0;
  padding: 0 1.2rem 1.15rem;
  color: var(--mute);
}

/* —— 下载带 —— */
.download-band {
  padding: 0 0 5.2rem;
}

.download-panel {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 1.5rem;
  align-items: center;
  padding: clamp(1.6rem, 4vw, 2.4rem);
  border-radius: 24px;
  background:
    linear-gradient(120deg, rgba(13, 143, 154, 0.16), rgba(31, 111, 235, 0.1)),
    #0d1b26;
  color: #eef6f8;
  box-shadow: var(--shadow);
}

.download-panel h2 {
  margin: 0 0 0.55rem;
  font-family: var(--font-display);
  font-size: clamp(1.55rem, 3vw, 2rem);
}

.download-panel p {
  margin: 0 0 1.2rem;
  color: rgba(238, 246, 248, 0.78);
}

.meta-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.2rem;
}

.meta-chips span {
  padding: 0.35rem 0.7rem;
  border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  font-size: 0.82rem;
  color: rgba(238, 246, 248, 0.9);
}

.download-aside {
  text-align: center;
  padding: 1.2rem;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.download-aside img {
  width: 96px;
  height: 96px;
  margin: 0 auto 0.9rem;
  border-radius: 22px;
  object-fit: cover;
}

.download-aside .btn {
  width: 100%;
}

.aside-note {
  margin: 0.85rem 0 0;
  font-size: 0.82rem;
  color: rgba(238, 246, 248, 0.62);
}

/* —— 页脚 —— */
.foot {
  border-top: 1px solid var(--line);
  padding: 2rem 0 2.6rem;
  color: var(--mute);
  font-size: 0.9rem;
}

.foot-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem 1.5rem;
  justify-content: space-between;
  align-items: center;
}

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

/* —— 动效 —— */
@keyframes riseIn {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes heroDrift {
  from { transform: scale(1.04) translate3d(0, 0, 0); }
  to { transform: scale(1.08) translate3d(-1.5%, 1%, 0); }
}

@keyframes meshPulse {
  0%, 100% { opacity: 0.55; }
  50% { opacity: 0.9; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .rise,
  .hero-plane,
  .hero-mesh {
    animation: none !important;
  }
  .rise {
    opacity: 1;
    transform: none;
  }
}

/* —— 响应式 —— */
@media (max-width: 960px) {
  .trust-rail,
  .ability-grid,
  .steps,
  .download-panel {
    grid-template-columns: 1fr 1fr;
  }

  .steps {
    grid-template-columns: 1fr 1fr;
  }

  .shots {
    --shot-gap: 1.1rem;
  }

  .shot:nth-child(4n + 1) { --wave: 28px; }
  .shot:nth-child(4n + 2) { --wave: 0; }
  .shot:nth-child(4n + 3) { --wave: 34px; }
  .shot:nth-child(4n + 4) { --wave: 10px; }
}

@media (max-width: 760px) {
  .burger {
    display: inline-block;
  }

  .nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 68px;
    display: none;
    flex-direction: column;
    gap: 0;
    margin: 0;
    padding: 0.5rem 1.2rem 1rem;
    background: rgba(255, 255, 255, 0.98);
    border-bottom: 1px solid var(--line);
  }

  .nav.is-open {
    display: flex;
  }

  .nav a {
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--line);
  }

  .mast-cta {
    display: none;
  }

  .hero {
    min-height: 78vh;
  }

  .hero-core {
    margin-bottom: 3.2rem;
  }

  .trust-rail,
  .ability-grid,
  .param-list,
  .steps,
  .download-panel {
    grid-template-columns: 1fr;
  }

  .shots {
    --shot-gap: 0.9rem;
    --shot-visible: 2;
  }

  .shot:nth-child(4n + 1) { --wave: 20px; }
  .shot:nth-child(4n + 2) { --wave: 0; }
  .shot:nth-child(4n + 3) { --wave: 24px; }
  .shot:nth-child(4n + 4) { --wave: 8px; }

  .block {
    padding: 3.6rem 0;
  }
}

@media (max-width: 720px) {
  .shots {
    --shot-visible: 2;
  }
}