/* ===================================================================
   全站样式表：Bumper Karts 首页（body.page-home）+ 法律页等共用。
   首页为深青街机渐变主背景；法律页等为浅色壳体。字体：Inter（全站统一无衬线）。
   =================================================================== */

:root {
  --max-width: 1200px;

  /* 全站字体：标题与正文同一套简洁无衬线（各 HTML 的 Google Fonts 链接需与此一致） */
  --font-display: 'Inter', system-ui, sans-serif;
  --font-body: 'Inter', system-ui, sans-serif;

  /* 法律页等沿用的设计令牌（隐私政策 / 服务条款 / 退款等页） */
  --white: #ffffff;
  --cream: #f4f5f7;
  --text-dark: #1a1d24;
  --text-mid: #4a5060;
  --text-soft: #6b7280;
  --primary: #00d9ff;
  --primary-dark: #00a8dd;
  --primary-light: #6cf0ff;
  --primary-pale: #c8f7ff;
  --accent: #ffc933;
  --accent-light: #ffe066;
  --accent-pale: #fff8e0;
  --ink-deep: #0c0e12;
  --shadow-soft: rgba(15, 20, 30, 0.08);
  --shadow-purple: rgba(0, 210, 255, 0.22);
  --shadow-glow: rgba(255, 200, 40, 0.45);
  --gradient-hero: linear-gradient(135deg, #063a5c 0%, #0a5a8a 45%, #0a7ab8 100%);
  --gradient-cta: linear-gradient(135deg, #ff9100 0%, #ffc933 45%, #00d9ff 100%);
  --gradient-pill: linear-gradient(135deg, #1aebff, #00b4e6);
  --gradient-warm: linear-gradient(135deg, #ffd000, #ff5520);

  /* Bumper Karts 首页：深青街机底 + 霓虹点缀（与 bk-blobs 叠层呼应） */
  --bk-page-gradient: linear-gradient(
    165deg,
    #050a14 0%,
    #0a1a32 18%,
    #0d3558 42%,
    #0c5a7a 68%,
    #0a7d8c 88%,
    #064a5c 100%
  );
  --bk-bg: #0c3558;
  --bk-surface: rgba(6, 20, 42, 0.52);
  --bk-surface-strong: rgba(4, 14, 36, 0.62);
  --bk-border: rgba(180, 235, 255, 0.22);
  --bk-text: #f4fbff;
  --bk-muted: rgba(220, 240, 255, 0.88);
  --bk-neon: #ffee58;
  --bk-neon-dim: #ffc107;
  --bk-cyan: #b8f4ff;
  --bk-orange: #ff6b35;
  --bk-grid: rgba(255, 255, 255, 0.07);
  --bk-grid-strong: rgba(120, 220, 255, 0.11);
  --bk-band: rgba(3, 12, 28, 0.55);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  font-family: var(--font-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 表单控件默认会用系统 UI 字体，显式继承才能用到 Inter */
button,
input,
select,
textarea {
  font-family: inherit;
}

body {
  font-family: var(--font-body);
  font-optical-sizing: auto;
  background: var(--cream);
  color: var(--text-dark);
  overflow-x: hidden;
}

body.page-home {
  background-color: #050a14;
  background-image: var(--bk-page-gradient);
  background-attachment: fixed;
  color: var(--bk-text);
}

@media (max-width: 968px) {
  body.page-home,
  body.page-recharge {
    background-attachment: scroll;
  }
}

/* --- 首页：透明不规则色块（blob）氛围层 --- */
.bk-blobs {
  display: none;
}
body.page-home .bk-blobs,
body.page-recharge .bk-blobs {
  display: block;
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.bk-blob {
  position: absolute;
  opacity: 0.55;
  filter: blur(0.5px);
  will-change: transform;
}

body.page-home .bk-blob--1,
body.page-recharge .bk-blob--1 {
  width: min(72vw, 520px);
  height: min(72vw, 520px);
  top: -12%;
  right: -8%;
  background: radial-gradient(
    ellipse 70% 60% at 40% 45%,
    rgba(0, 220, 255, 0.22) 0%,
    rgba(0, 140, 200, 0.08) 45%,
    transparent 70%
  );
  border-radius: 58% 42% 62% 38% / 48% 55% 45% 52%;
  animation: bk-blob-1 28s ease-in-out infinite;
}

body.page-home .bk-blob--2,
body.page-recharge .bk-blob--2 {
  width: min(90vw, 640px);
  height: min(55vw, 420px);
  bottom: -5%;
  left: -18%;
  background: linear-gradient(
    125deg,
    rgba(255, 107, 53, 0.14) 0%,
    rgba(255, 200, 60, 0.1) 40%,
    transparent 75%
  );
  border-radius: 45% 55% 50% 50% / 55% 45% 55% 45%;
  animation: bk-blob-2 34s ease-in-out infinite;
}

body.page-home .bk-blob--3,
body.page-recharge .bk-blob--3 {
  width: min(50vw, 380px);
  height: min(50vw, 380px);
  top: 38%;
  left: 8%;
  background: radial-gradient(
    circle at 30% 30%,
    rgba(160, 110, 255, 0.2) 0%,
    rgba(80, 40, 180, 0.06) 50%,
    transparent 72%
  );
  border-radius: 40% 60% 55% 45% / 55% 40% 60% 45%;
  animation: bk-blob-3 22s ease-in-out infinite 2s;
}

body.page-home .bk-blob--4,
body.page-recharge .bk-blob--4 {
  width: min(65vw, 480px);
  height: min(40vw, 320px);
  top: 52%;
  right: -6%;
  background: radial-gradient(
    ellipse 80% 55% at 60% 50%,
    rgba(0, 255, 200, 0.1) 0%,
    transparent 65%
  );
  border-radius: 63% 37% 48% 52% / 42% 58% 42% 58%;
  animation: bk-blob-4 26s ease-in-out infinite 1s;
}

body.page-home .bk-blob--5,
body.page-recharge .bk-blob--5 {
  width: min(100vw, 900px);
  height: min(45vh, 360px);
  top: 18%;
  left: 50%;
  background: radial-gradient(
    ellipse 55% 80% at 50% 50%,
    rgba(255, 255, 255, 0.06) 0%,
    transparent 65%
  );
  border-radius: 50% 50% 48% 52% / 42% 58% 38% 62%;
  opacity: 0.85;
  animation: bk-blob-5 40s ease-in-out infinite 0.5s;
}

@keyframes bk-blob-1 {
  0%, 100% { transform: rotate(-18deg) translate(0, 0); }
  50% { transform: rotate(-14deg) translate(18px, -14px); }
}

@keyframes bk-blob-2 {
  0%, 100% { transform: rotate(12deg) translate(0, 0); }
  50% { transform: rotate(8deg) translate(-14px, 10px); }
}

@keyframes bk-blob-3 {
  0%, 100% { transform: rotate(25deg) translate(0, 0); }
  50% { transform: rotate(22deg) translate(10px, 16px); }
}

@keyframes bk-blob-4 {
  0%, 100% { transform: rotate(-8deg) translate(0, 0); }
  50% { transform: rotate(-5deg) translate(-12px, -10px); }
}

@keyframes bk-blob-5 {
  0%, 100% { transform: translateX(-50%) rotate(-2deg) translate(0, 0); }
  50% { transform: translateX(-50%) rotate(1deg) translate(0, 14px); }
}

@media (prefers-reduced-motion: reduce) {
  body.page-home .bk-blob,
  body.page-recharge .bk-blob {
    animation: none !important;
  }
}

/* --- 首页 / 充值页 装饰背景 --- */
.bk-grid-bg {
  display: none;
}
body.page-home .bk-grid-bg,
body.page-recharge .bk-grid-bg {
  display: block;
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--bk-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--bk-grid) 1px, transparent 1px),
    linear-gradient(
      -18deg,
      transparent 0%,
      transparent 48%,
      var(--bk-grid-strong) 49%,
      var(--bk-grid-strong) 51%,
      transparent 52%,
      transparent 100%
    );
  background-size: 44px 44px, 44px 44px, 100% 100%;
  mask-image: radial-gradient(ellipse 95% 85% at 50% 15%, black 0%, transparent 72%);
}

.bk-scanlines {
  display: none;
}
body.page-home .bk-scanlines,
body.page-recharge .bk-scanlines {
  display: block;
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  opacity: 0.035;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 2px,
    rgba(255, 255, 255, 0.22) 2px,
    rgba(255, 255, 255, 0.22) 4px
  );
}

/* ===================================================================
   导航栏（首页 + 法律页）
   =================================================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 0.85rem 2rem;
  transition: background 0.35s ease, box-shadow 0.35s ease, border-color 0.35s ease;
}

/* 法律页等：默认实心顶栏 */
.navbar.scrolled {
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(16px);
  box-shadow: 0 4px 24px var(--shadow-soft);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

body.page-home .navbar.scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.45);
  box-shadow: 0 8px 28px rgba(0, 60, 90, 0.2);
}

body.page-home .navbar.scrolled .nav-logo-text {
  color: var(--text-dark);
}

body.page-home .navbar.scrolled .nav-links a {
  color: var(--text-mid);
}
body.page-home .navbar.scrolled .nav-links a:hover {
  color: var(--primary-dark);
}
body.page-home .navbar.scrolled .nav-links a::after {
  background: var(--primary);
}

body.page-home .navbar.scrolled .mobile-menu-btn span {
  background: var(--text-dark);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.nav-logo img {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  object-fit: cover;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25);
}

.nav-logo-text {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.35rem;
  letter-spacing: -0.02em;
  color: var(--text-dark);
}

body.page-home .nav-logo-text {
  color: var(--bk-text);
}

.navbar.scrolled .nav-logo-text {
  background: none;
  -webkit-text-fill-color: unset;
}

body.page-home .navbar:not(.scrolled) .nav-logo-text {
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.5);
}

.nav-links {
  display: flex;
  gap: 1.35rem;
  list-style: none;
  align-items: center;
}

.nav-links a {
  color: var(--text-mid);
  text-decoration: none;
  font-weight: 700;
  font-size: 0.88rem;
  transition: color 0.2s ease;
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -3px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  border-radius: 2px;
  transition: width 0.25s ease;
}

.nav-links a:hover {
  color: var(--primary-dark);
}
.nav-links a:hover::after { width: 100%; }

body.page-home .navbar:not(.scrolled) .nav-links a {
  color: rgba(255, 255, 255, 0.88);
}
body.page-home .navbar:not(.scrolled) .nav-links a::after {
  background: var(--bk-neon);
}
body.page-home .navbar:not(.scrolled) .nav-links a:hover {
  color: var(--bk-neon);
}

.nav-recharge-link {
  background: var(--gradient-warm);
  color: #2a1500 !important;
  padding: 0.32rem 0.9rem;
  border-radius: 8px;
  font-weight: 800 !important;
  font-size: 0.82rem !important;
  transition: transform 0.2s ease, box-shadow 0.2s ease !important;
  box-shadow: 0 2px 12px rgba(255, 122, 46, 0.35);
}
.nav-recharge-link::after { display: none !important; }
.nav-recharge-link:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(255, 122, 46, 0.45) !important;
}

body.page-home .navbar.scrolled .nav-recharge-link {
  box-shadow: 0 2px 14px rgba(255, 204, 0, 0.25);
}

.nav-download-btn {
  background: var(--gradient-pill);
  color: var(--white);
  text-decoration: none;
  padding: 0.55rem 1.25rem;
  border-radius: 10px;
  font-weight: 800;
  font-size: 0.82rem;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 4px 16px rgba(0, 149, 204, 0.35);
}

.nav-download-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 194, 255, 0.4);
}

body.page-home .navbar:not(.scrolled) .nav-download-btn {
  background: linear-gradient(135deg, var(--bk-neon), var(--bk-orange));
  color: #1a0f00;
  box-shadow: 0 4px 20px rgba(255, 204, 0, 0.35);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
  flex-direction: column;
  gap: 5px;
}

.mobile-menu-btn span {
  display: block;
  width: 26px;
  height: 3px;
  background: var(--text-dark);
  border-radius: 2px;
  transition: background 0.25s ease;
}

body.page-home .navbar:not(.scrolled) .mobile-menu-btn span {
  background: var(--white);
}

.mobile-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(16px);
  box-shadow: 0 12px 32px var(--shadow-soft);
  padding: 1rem 2rem;
}

body.page-home .mobile-menu {
  background: rgba(0, 45, 72, 0.94);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--bk-border);
}

.mobile-menu.open { display: block; }

.mobile-menu a {
  display: block;
  color: var(--text-dark);
  text-decoration: none;
  font-weight: 700;
  padding: 0.75rem 0;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

body.page-home .mobile-menu a {
  color: var(--bk-text);
  border-bottom-color: var(--bk-border);
}

.mobile-menu a:last-child { border-bottom: none; }

.mobile-menu-recharge { color: var(--accent) !important; }
.mobile-menu-download { color: var(--primary-dark) !important; font-weight: 800 !important; }

body.page-home .mobile-menu-download {
  color: var(--bk-cyan) !important;
}

/* ===================================================================
   Bumper Karts — Hero 首屏
   =================================================================== */
.bk-hero {
  position: relative;
  z-index: 2;
  min-height: 100vh;
  padding: 6.5rem 2rem 4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: transparent;
}

.bk-hero-glow {
  position: absolute;
  width: min(95vw, 780px);
  height: min(95vw, 780px);
  border-radius: 50%;
  top: -22%;
  left: 50%;
  transform: translateX(-50%);
  background:
    radial-gradient(circle at 35% 35%, rgba(255, 230, 100, 0.12) 0%, transparent 42%),
    radial-gradient(circle at 60% 55%, rgba(0, 210, 255, 0.14) 0%, transparent 48%),
    radial-gradient(circle at 50% 100%, rgba(100, 80, 255, 0.08) 0%, transparent 55%);
  pointer-events: none;
}

.bk-hero-inner {
  position: relative;
  z-index: 1;
  max-width: var(--max-width);
  width: 100%;
  display: grid;
  grid-template-columns: 1fr 1.05fr;
  gap: 3rem;
  align-items: center;
}

.bk-eyebrow {
  font-family: var(--font-display);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: #ffe082;
  text-shadow: 0 0 24px rgba(255, 200, 80, 0.35), 0 2px 8px rgba(0, 0, 0, 0.45);
  margin-bottom: 1rem;
}

.bk-hero-title {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(2.6rem, 7vw, 4.25rem);
  line-height: 0.95;
  letter-spacing: -0.03em;
  color: var(--bk-text);
  margin-bottom: 1.25rem;
  text-shadow: 0 2px 24px rgba(0, 40, 70, 0.35);
}

.bk-hero-title-accent {
  display: block;
  color: var(--bk-neon);
  text-shadow:
    0 0 32px rgba(255, 234, 88, 0.55),
    0 0 64px rgba(0, 200, 255, 0.22),
    0 0 100px rgba(255, 120, 0, 0.2),
    0 2px 0 rgba(100, 60, 0, 0.35);
}

.bk-hero-lead {
  font-size: clamp(1rem, 1.8vw, 1.15rem);
  line-height: 1.75;
  color: var(--bk-muted);
  max-width: 34rem;
  margin-bottom: 2rem;
}

.bk-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
}

.bk-btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  font-family: var(--font-display);
  font-weight: 800;
  border-radius: 12px;
  padding: 0.9rem 1.5rem;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.bk-btn-play {
  background: var(--white);
  color: var(--text-dark);
  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.35);
}
.bk-btn-play:hover {
  transform: translateY(-3px);
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.45);
}

.bk-btn-play-text {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
  text-align: left;
}

.bk-btn-play-label {
  font-family: var(--font-body);
  font-size: 0.68rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  opacity: 0.65;
}

.bk-btn-play-name {
  font-size: 1.05rem;
}

.bk-btn-secondary {
  background: rgba(255, 255, 255, 0.14);
  color: var(--bk-text);
  border: 1px solid rgba(255, 255, 255, 0.45);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2);
}
.bk-btn-secondary:hover {
  background: rgba(255, 255, 255, 0.26);
  border-color: rgba(255, 234, 80, 0.75);
  transform: translateY(-3px);
}

.bk-btn-lg {
  padding: 1rem 1.75rem;
  border-radius: 14px;
}

.bk-hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.75rem;
}

.bk-tag {
  font-family: var(--font-display);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  background: rgba(0, 24, 44, 0.55);
  border: 1px solid rgba(120, 220, 255, 0.3);
  color: var(--bk-cyan);
  box-shadow: 0 0 24px rgba(0, 200, 255, 0.1);
}

.bk-hero-visual {
  position: relative;
}

.bk-hero-frame {
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid var(--bk-border);
  box-shadow:
    0 28px 70px rgba(0, 0, 0, 0.5),
    0 0 0 1px rgba(0, 220, 255, 0.14),
    0 0 90px rgba(0, 170, 210, 0.18);
  background: var(--bk-surface-strong);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.bk-hero-frame-bar {
  display: flex;
  gap: 6px;
  padding: 10px 14px;
  background: linear-gradient(180deg, #1c2430 0%, #141a22 100%);
  border-bottom: 1px solid var(--bk-border);
}

.bk-hero-frame-bar span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #3a4454;
}
.bk-hero-frame-bar span:nth-child(1) { background: #ff5f57; }
.bk-hero-frame-bar span:nth-child(2) { background: #febc2e; }
.bk-hero-frame-bar span:nth-child(3) { background: #28c840; }

.bk-hero-frame-screen {
  aspect-ratio: 16 / 9;
  background: #000;
}

.bk-hero-frame-screen img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.bk-hero-caption {
  margin-top: 0.85rem;
  font-size: 0.82rem;
  color: var(--bk-muted);
  text-align: center;
}

/* ===================================================================
   通用区块容器
   =================================================================== */
.bk-wrap {
  max-width: var(--max-width);
  margin: 0 auto;
}

.bk-section {
  position: relative;
  z-index: 2;
  padding: 5rem 2rem;
}

.bk-section-head {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 3rem;
}

.bk-kicker {
  font-family: var(--font-display);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #7dfffc;
  text-shadow: 0 0 18px rgba(0, 255, 255, 0.45);
  display: inline-block;
  margin-bottom: 0.75rem;
}

.bk-h2 {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.85rem, 4vw, 2.75rem);
  letter-spacing: -0.02em;
  color: var(--bk-text);
  margin-bottom: 0.75rem;
}

.bk-sub {
  font-size: 1.05rem;
  color: var(--bk-muted);
  line-height: 1.65;
}

/* --- 玩法说明 --- */
.bk-howto {
  background: var(--bk-band);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-top: 1px solid var(--bk-border);
  border-bottom: 1px solid var(--bk-border);
}

.bk-howto-list {
  list-style: none;
  display: grid;
  gap: 1.25rem;
}

@media (min-width: 900px) {
  .bk-howto-list {
    grid-template-columns: repeat(2, 1fr);
  }
}

.bk-howto-item {
  display: flex;
  gap: 1.25rem;
  padding: 1.5rem 1.35rem;
  background: var(--bk-surface);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-radius: 14px;
  border: 1px solid var(--bk-border);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.bk-howto-item:hover {
  border-color: rgba(255, 255, 255, 0.45);
  box-shadow: 0 12px 40px rgba(0, 40, 70, 0.25);
}

.bk-howto-num {
  flex-shrink: 0;
  width: 2.5rem;
  height: 2.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.1rem;
  color: #042f42;
  background: linear-gradient(135deg, var(--bk-neon), var(--bk-orange));
  border-radius: 10px;
}

.bk-howto-item h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--bk-text);
  margin-bottom: 0.35rem;
}

.bk-howto-item p {
  font-size: 0.92rem;
  color: var(--bk-muted);
  line-height: 1.6;
}

/* --- 游戏模式 --- */
.bk-modes {
  background: transparent;
}

.bk-modes-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}

.bk-mode-card {
  padding: 1.75rem 1.35rem;
  border-radius: 16px;
  background: linear-gradient(165deg, var(--bk-surface) 0%, rgba(4, 28, 52, 0.75) 100%);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--bk-border);
  transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
  box-shadow: 0 10px 36px rgba(0, 0, 0, 0.25);
}

.bk-mode-card:hover {
  transform: translateY(-6px);
  border-color: rgba(120, 220, 255, 0.42);
  box-shadow:
    0 18px 44px rgba(0, 0, 0, 0.32),
    0 0 0 1px rgba(255, 230, 100, 0.15),
    0 0 56px rgba(0, 180, 220, 0.15);
}

.bk-mode-icon {
  font-size: 2rem;
  display: block;
  margin-bottom: 1rem;
  line-height: 1;
}

.bk-mode-card h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--bk-text);
  margin-bottom: 0.5rem;
}

.bk-mode-card p {
  font-size: 0.88rem;
  color: var(--bk-muted);
  line-height: 1.55;
}

/* --- 特色功能 --- */
.bk-features {
  background: var(--bk-band);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-top: 1px solid var(--bk-border);
}

.bk-features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}

.bk-feature-card {
  padding: 1.6rem 1.35rem;
  border-radius: 14px;
  background: var(--bk-surface);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--bk-border);
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.2);
}

.bk-feature-card:hover {
  transform: translateY(-4px);
  border-color: rgba(120, 220, 255, 0.35);
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.26), 0 0 48px rgba(0, 160, 200, 0.12);
}

.bk-feature-wide {
  grid-column: span 3;
}

@media (max-width: 899px) {
  .bk-feature-wide { grid-column: span 1; }
}

.bk-feature-emoji {
  font-size: 2rem;
  line-height: 1;
  display: block;
  margin-bottom: 0.85rem;
}

.bk-feature-card h3 {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 800;
  color: var(--bk-text);
  margin-bottom: 0.4rem;
}

.bk-feature-card p {
  font-size: 0.88rem;
  color: var(--bk-muted);
  line-height: 1.55;
}

/* --- 适合人群 --- */
.bk-perfect {
  background: transparent;
}

.bk-perfect-list {
  list-style: none;
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.bk-perfect-list li {
  position: relative;
  padding: 1.15rem 1.25rem 1.15rem 3rem;
  background: var(--bk-surface);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--bk-border);
  border-radius: 12px;
  font-size: 1rem;
  color: var(--bk-muted);
  line-height: 1.55;
}

.bk-perfect-list li::before {
  content: '';
  position: absolute;
  left: 1.15rem;
  top: 50%;
  transform: translateY(-50%);
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--bk-cyan), var(--primary-dark));
  box-shadow: 0 0 12px rgba(46, 230, 255, 0.5);
}

/* --- 截图画廊 --- */
.bk-legacy-anchor {
  height: 0;
  overflow: hidden;
  scroll-margin-top: 96px;
}

.bk-gallery {
  background: var(--bk-band);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-top: 1px solid var(--bk-border);
}

.bk-gallery-grid {
  display: grid;
  /* minmax(0,1fr) 避免图片 intrinsic 宽度把列撑破导致横向溢出 */
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1rem;
}

.bk-shot {
  margin: 0;
  min-width: 0;
  aspect-ratio: 16 / 9;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--bk-border);
  background: #0a0c10;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.35);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.bk-shot:hover {
  transform: scale(1.02);
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.45);
}

/* 完整显示横屏截图：非 16:9 源图时留黑边，避免 cover 裁切过度 */
.bk-shot img {
  width: 100%;
  height: 100%;
  min-width: 0;
  min-height: 0;
  object-fit: contain;
  object-position: center;
  display: block;
}

/* --- 下载号召区 --- */
.bk-cta {
  position: relative;
  z-index: 2;
  padding: 5rem 2rem;
  text-align: center;
  background: linear-gradient(
    180deg,
    rgba(4, 14, 32, 0.35) 0%,
    rgba(6, 28, 52, 0.62) 50%,
    rgba(4, 18, 40, 0.55) 100%
  );
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-top: 1px solid var(--bk-border);
}

.bk-cta-inner {
  max-width: 720px;
  margin: 0 auto;
}

.bk-cta-title {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  color: var(--bk-text);
  margin-bottom: 1rem;
  line-height: 1.2;
}

.bk-cta-desc {
  font-size: 1.08rem;
  color: var(--bk-muted);
  line-height: 1.65;
  margin-bottom: 1rem;
}

.bk-cta-disclaimer {
  font-size: 0.88rem;
  color: rgba(154, 163, 178, 0.85);
  margin-bottom: 2rem;
}

.bk-cta-btns {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
}

.bk-btn-outline {
  background: transparent;
  color: var(--bk-text);
  border: 2px solid rgba(255, 238, 80, 0.85);
  box-shadow: 0 0 20px rgba(255, 220, 60, 0.25);
}
.bk-btn-outline:hover {
  background: rgba(255, 238, 80, 0.18);
  border-color: #fff566;
  box-shadow: 0 0 28px rgba(255, 230, 80, 0.45);
  transform: translateY(-3px);
}

/* ===================================================================
   联系区（首页 + .section-header 等共用类名）
   =================================================================== */
.contact {
  position: relative;
  z-index: 2;
  padding: 5rem 2rem;
}

body.page-home .contact {
  background: #e8eaef;
  color: var(--text-dark);
}

.contact-inner {
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
}

.contact .section-header {
  margin-bottom: 2rem;
}

.section-tag {
  display: inline-block;
  background: var(--primary-pale);
  color: var(--primary-dark);
  padding: 0.35rem 1rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 800;
  margin-bottom: 0.85rem;
  letter-spacing: 0.04em;
}

body.page-home .contact .section-tag {
  background: rgba(0, 149, 204, 0.12);
  color: var(--primary-dark);
}

.section-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.85rem, 4vw, 2.6rem);
  background: var(--gradient-pill);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 0.75rem;
  line-height: 1.2;
}

body.page-home .contact .section-title {
  font-family: var(--font-display);
  font-weight: 900;
  background: none;
  -webkit-text-fill-color: unset;
  color: var(--text-dark);
}

.section-desc {
  font-size: 1.02rem;
  color: var(--text-mid);
  line-height: 1.65;
  max-width: 520px;
  margin: 0 auto;
}

.contact-card {
  background: var(--white);
  border-radius: 20px;
  padding: 2.4rem 2rem;
  box-shadow: 0 12px 40px var(--shadow-soft);
  border: 1px solid rgba(0, 0, 0, 0.06);
  margin-top: 0.5rem;
}

.contact-email-link {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  background: linear-gradient(135deg, var(--primary-pale), var(--accent-pale));
  color: var(--primary-dark);
  text-decoration: none;
  padding: 1rem 2rem;
  border-radius: 14px;
  font-weight: 800;
  font-size: 1rem;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  border: 2px solid var(--primary-light);
}

.contact-email-link:hover {
  background: var(--gradient-pill);
  color: var(--white);
  transform: translateY(-3px);
  box-shadow: 0 12px 32px rgba(0, 149, 204, 0.35);
}

.contact-email-link svg {
  width: 22px;
  height: 22px;
  flex-shrink: 0;
}

.contact-note {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--text-soft);
}

/* ===================================================================
   页脚
   =================================================================== */
.footer {
  position: relative;
  z-index: 2;
  background: var(--ink-deep);
  color: rgba(255, 255, 255, 0.78);
  padding: 2.75rem 2rem;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 2rem;
  flex-wrap: wrap;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 0.75rem;
}

.footer-brand img {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  object-fit: cover;
}

.footer-brand-name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 1.2rem;
  color: var(--white);
}

body:not(.page-home) .footer-brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.02em;
}

.footer-company-info {
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.52);
  line-height: 1.8;
  margin-top: 0.35rem;
}

.footer-links-group {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.footer-links-group a {
  color: rgba(255, 255, 255, 0.68);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 600;
  transition: color 0.2s ease;
}

.footer-links-group a:hover {
  color: var(--bk-neon);
}

.footer-recharge-link {
  color: var(--bk-neon) !important;
  font-weight: 800 !important;
}

.footer-appstore-link {
  color: rgba(255, 255, 255, 0.55);
  font-size: 0.85rem;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.footer-appstore-link:hover {
  color: var(--bk-cyan);
}

.footer-bottom {
  max-width: var(--max-width);
  margin: 1.5rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-copyright {
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.42);
}

/* ===================================================================
   法律页（隐私 / 条款 / 退款）
   =================================================================== */
.legal-hero {
  background: var(--gradient-hero);
  padding: 8.5rem 2rem 4rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.legal-hero::before,
.legal-hero::after {
  content: '';
  position: absolute;
  border-radius: 50%;
  filter: blur(2px);
  opacity: 0.35;
  pointer-events: none;
}

.legal-hero::before {
  width: 200px;
  height: 200px;
  top: -50px;
  left: -40px;
  background: radial-gradient(circle at 30% 30%, rgba(255, 176, 32, 0.5), transparent 70%);
}

.legal-hero::after {
  width: 260px;
  height: 260px;
  bottom: -90px;
  right: -60px;
  background: radial-gradient(circle at 30% 30%, rgba(0, 194, 255, 0.35), transparent 70%);
}

.legal-hero-inner {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.legal-hero h1 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  color: var(--white);
  text-shadow: 2px 6px 18px rgba(0, 0, 0, 0.25);
  margin-bottom: 0.6rem;
}

.legal-hero .legal-meta {
  color: rgba(255, 255, 255, 0.9);
  font-size: 0.95rem;
  font-weight: 600;
}

.legal-page {
  max-width: 1100px;
  margin: 0 auto;
  padding: 4rem 2rem 5rem;
}

.legal-content {
  background: var(--white);
  border-radius: 24px;
  padding: 3rem 2.5rem;
  box-shadow: 0 18px 60px var(--shadow-soft);
  border: 1px solid rgba(0, 0, 0, 0.06);
  font-size: 0.96rem;
  color: var(--text-dark);
  line-height: 1.8;
}

.legal-content h2 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--primary-dark);
  margin: 2rem 0 0.7rem;
  padding-bottom: 0.4rem;
  border-bottom: 2px solid var(--primary-pale);
}

.legal-content h2:first-of-type {
  margin-top: 0.5rem;
}

.legal-content h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--accent);
  margin: 1.4rem 0 0.5rem;
}

.legal-content p { margin-bottom: 0.85rem; }

.legal-content ul,
.legal-content ol {
  padding-left: 1.5rem;
  margin-bottom: 0.85rem;
}

.legal-content li { margin-bottom: 0.4rem; }

.legal-content a {
  color: var(--primary-dark);
  font-weight: 700;
}

.legal-content a:hover { text-decoration: underline; }

.legal-content strong { color: var(--text-dark); }

.legal-back {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 1.5rem;
  color: var(--primary-dark);
  text-decoration: none;
  font-weight: 800;
  font-size: 0.95rem;
}

.legal-back:hover {
  color: var(--primary);
}

/* ===================================================================
   法律页导航（非首页：浅色顶栏）
   =================================================================== */
body:not(.page-home) .navbar:not(.scrolled) {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  box-shadow: 0 2px 16px var(--shadow-soft);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

body:not(.page-home) .nav-logo-text {
  background: var(--gradient-pill);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* ===================================================================
   响应式断点
   =================================================================== */
@media (max-width: 1024px) {
  .bk-modes-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .bk-features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .bk-gallery-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 968px) {
  .nav-links,
  .nav-download-btn {
    display: none;
  }
  .mobile-menu-btn {
    display: flex;
  }
  .bk-hero-inner {
    grid-template-columns: 1fr;
    gap: 2.5rem;
    text-align: center;
  }
  .bk-hero-lead {
    margin-left: auto;
    margin-right: auto;
  }
  .bk-hero-actions {
    justify-content: center;
  }
  .bk-hero-tags {
    justify-content: center;
  }
  .bk-hero-caption {
    text-align: center;
  }
}

@media (max-width: 640px) {
  .bk-modes-grid {
    grid-template-columns: 1fr;
  }
  .bk-features-grid {
    grid-template-columns: 1fr;
  }
  .bk-gallery-grid {
    grid-template-columns: minmax(0, 1fr);
  }
  .bk-hero {
    padding: 5.5rem 1.25rem 3rem;
  }
  .bk-section {
    padding: 3.5rem 1.25rem;
  }
  .footer-inner {
    flex-direction: column;
  }
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
  .legal-page {
    padding: 2.5rem 1.2rem 3rem;
  }
  .legal-content {
    padding: 2rem 1.35rem;
    border-radius: 18px;
  }
}