/* ==========================================================================
   KeepVPN 企业级推广官网设计系统 (Design Tokens & Responsive Architecture)
   兼顾 Bootstrap 5.3.8 兼容性与离线内网自完备排版能力
   ========================================================================== */

:root {
  /* 色彩系统：工程通透白 + 深邃零信任藏青 + 精密安全蓝 */
  --kv-bg-page: #ffffff;
  --kv-bg-subtle: #f8fafc;
  --kv-bg-muted: #f1f5f9;
  --kv-bg-dark: #0b1120;
  --kv-bg-dark-card: #111827;
  --kv-bg-dark-elevated: #1e293b;

  --kv-text-primary: #0f172a;
  --kv-text-secondary: #334155;
  --kv-text-muted: #64748b;
  --kv-text-inverse: #f8fafc;
  --kv-text-inverse-muted: #94a3b8;

  --kv-brand: #2563eb;
  --kv-brand-hover: #1d4ed8;
  --kv-brand-light: #38bdf8;
  --kv-brand-soft: rgba(37, 99, 235, 0.08);
  --kv-brand-border: rgba(37, 99, 235, 0.24);

  --kv-success: #059669;
  --kv-success-soft: rgba(5, 150, 105, 0.1);
  --kv-warning: #d97706;
  --kv-danger: #dc2626;
  --kv-danger-soft: rgba(220, 38, 38, 0.12);

  --kv-border: #e2e8f0;
  --kv-border-strong: #cbd5e1;
  --kv-border-dark: rgba(255, 255, 255, 0.1);

  /* 字体家族：系统原生高性能栈，避免外网字体加载阻塞首屏 (LCP) */
  --kv-font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "HarmonyOS Sans SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --kv-font-mono: "JetBrains Mono", "Cascadia Code", "Fira Code", Consolas, "Courier New", monospace;

  /* 空间、圆角与阴影 Tokens */
  --kv-nav-height: 68px;
  --kv-radius-sm: 8px;
  --kv-radius-md: 12px;
  --kv-radius-lg: 16px;
  --kv-radius-xl: 22px;

  --kv-shadow-xs: 0 1px 2px rgba(15, 23, 42, 0.05);
  --kv-shadow-sm: 0 4px 12px -2px rgba(15, 23, 42, 0.06), 0 1px 3px rgba(15, 23, 42, 0.04);
  --kv-shadow-md: 0 12px 32px -6px rgba(15, 23, 42, 0.1), 0 4px 10px -2px rgba(15, 23, 42, 0.04);
  --kv-shadow-lg: 0 24px 56px -12px rgba(15, 23, 42, 0.18), 0 8px 20px -6px rgba(15, 23, 42, 0.08);
  --kv-shadow-dark: 0 24px 60px -12px rgba(2, 6, 23, 0.65);

  --kv-transition: 0.22s cubic-bezier(0.22, 1, 0.36, 1);
  --kv-max-width: 1220px;
}

/* 基础重置 */
*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  overflow-x: clip;
}

body {
  margin: 0;
  font-family: var(--kv-font-sans);
  color: var(--kv-text-primary);
  background-color: var(--kv-bg-page);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: clip;
}

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

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

button {
  font-family: inherit;
  cursor: pointer;
}

:focus-visible {
  outline: 2px solid var(--kv-brand);
  outline-offset: 2px;
}

.kv-mono {
  font-family: var(--kv-font-mono);
}

/* 统一版心容器与锚点偏移防护（防粘性导航遮住章节标题） */
.kv-container {
  width: 100%;
  max-width: var(--kv-max-width);
  margin-inline: auto;
  padding-inline: 24px;
}

section[id],
div[id] {
  scroll-margin-top: calc(var(--kv-nav-height) + 18px);
}

/* ==========================================================================
   顶部信赖条与导航栏
   ========================================================================== */
.kv-top-notice {
  background: var(--kv-bg-dark);
  color: #cbd5e1;
  font-size: 0.8125rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  padding: 8px 0;
}

.kv-top-notice-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px 24px;
}

.kv-top-notice-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.kv-dot-live {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #10b981;
  box-shadow: 0 0 8px rgba(16, 185, 129, 0.75);
  display: inline-block;
  flex-shrink: 0;
}

.kv-header {
  position: sticky;
  top: 0;
  z-index: 900;
  height: var(--kv-nav-height);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--kv-border);
  transition: box-shadow var(--kv-transition), background-color var(--kv-transition);
}

.kv-header.is-scrolled {
  background: rgba(255, 255, 255, 0.97);
  box-shadow: var(--kv-shadow-sm);
}

.kv-nav-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.kv-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.kv-brand-logo {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #0f172a;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.22);
}

.kv-brand-name {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--kv-text-primary);
}

.kv-brand-name span {
  color: var(--kv-brand);
}

.kv-brand-tag {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--kv-success-soft);
  color: var(--kv-success);
  border: 1px solid rgba(5, 150, 105, 0.25);
  white-space: nowrap;
}

.kv-nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.kv-nav-link {
  display: inline-block;
  padding: 8px 13px;
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--kv-text-secondary);
  border-radius: var(--kv-radius-sm);
  transition: color var(--kv-transition), background-color var(--kv-transition);
  white-space: nowrap;
}

.kv-nav-link:hover {
  color: var(--kv-brand);
  background: var(--kv-brand-soft);
}

.kv-nav-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.kv-mobile-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border-radius: var(--kv-radius-sm);
  border: 1px solid var(--kv-border);
  background: var(--kv-bg-page);
  color: var(--kv-text-primary);
  align-items: center;
  justify-content: center;
}

/* 按钮体系 */
.kv-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  border-radius: var(--kv-radius-sm);
  border: 1px solid transparent;
  padding: 10px 18px;
  font-size: 0.9375rem;
  line-height: 1.25;
  transition: all var(--kv-transition);
  white-space: nowrap;
}

.kv-btn-lg {
  padding: 13px 24px;
  font-size: 1rem;
  border-radius: 10px;
}

.kv-btn-sm {
  padding: 8px 14px;
  font-size: 0.875rem;
}

.kv-btn-primary {
  background: var(--kv-brand);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.28);
}

.kv-btn-primary:hover {
  background: var(--kv-brand-hover);
  color: #ffffff;
  transform: translateY(-1px);
  box-shadow: 0 8px 22px rgba(37, 99, 235, 0.34);
}

.kv-btn-secondary {
  background: #ffffff;
  color: var(--kv-text-primary);
  border-color: var(--kv-border-strong);
  box-shadow: var(--kv-shadow-xs);
}

.kv-btn-secondary:hover {
  border-color: var(--kv-brand);
  color: var(--kv-brand);
  background: #f8fafc;
  transform: translateY(-1px);
}

.kv-btn-dark-ghost {
  background: rgba(255, 255, 255, 0.08);
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.2);
}

.kv-btn-dark-ghost:hover {
  background: rgba(255, 255, 255, 0.16);
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.35);
}

/* ==========================================================================
   Hero 首屏模块：精密工程风 + 双端实景同框展示
   ========================================================================== */
.kv-hero {
  position: relative;
  padding: 58px 0 72px;
  background:
    radial-gradient(ellipse 80% 60% at 50% -10%, rgba(37, 99, 235, 0.09) 0%, transparent 70%),
    linear-gradient(180deg, #f8fafc 0%, #ffffff 100%);
  border-bottom: 1px solid var(--kv-border);
  overflow: hidden;
}

.kv-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(15, 23, 42, 0.03) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(15, 23, 42, 0.03) 1px, transparent 1px);
  background-size: 40px 40px;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.75) 0%, transparent 90%);
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.75) 0%, transparent 90%);
  pointer-events: none;
}

.kv-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.02fr) minmax(0, 1.08fr);
  gap: 44px;
  align-items: center;
}

.kv-hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: 999px;
  background: #ffffff;
  border: 1px solid var(--kv-brand-border);
  color: var(--kv-brand);
  font-size: 0.84rem;
  font-weight: 600;
  box-shadow: var(--kv-shadow-xs);
  margin-bottom: 20px;
}

.kv-hero-title {
  font-size: clamp(2rem, 3.6vw, 3.15rem);
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.03em;
  color: var(--kv-text-primary);
  margin: 0 0 18px;
}

.kv-hero-title .kv-highlight {
  background: linear-gradient(135deg, #2563eb 0%, #0284c7 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.kv-hero-desc {
  font-size: 1.0625rem;
  line-height: 1.72;
  color: var(--kv-text-secondary);
  margin: 0 0 26px;
  max-width: 560px;
}

.kv-hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 26px;
}

.kv-hero-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px 18px;
  padding-top: 20px;
  border-top: 1px solid var(--kv-border);
}

.kv-fact-item {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--kv-text-secondary);
}

.kv-fact-icon {
  color: var(--kv-success);
  flex-shrink: 0;
  margin-top: 3px;
}

/* Hero 双端真实产品同框区 */
.kv-hero-stage {
  position: relative;
  padding-bottom: 22px;
  padding-right: 18px;
}

.kv-browser-frame {
  background: #ffffff;
  border: 1px solid var(--kv-border-strong);
  border-radius: var(--kv-radius-lg);
  box-shadow: var(--kv-shadow-lg);
  overflow: hidden;
  transition: transform var(--kv-transition);
}

.kv-browser-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 9px 14px;
  background: #f8fafc;
  border-bottom: 1px solid var(--kv-border);
}

.kv-browser-dots {
  display: flex;
  align-items: center;
  gap: 6px;
}

.kv-browser-dots span {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: #cbd5e1;
}

.kv-browser-dots span:nth-child(1) { background: #fca5a5; }
.kv-browser-dots span:nth-child(2) { background: #fcd34d; }
.kv-browser-dots span:nth-child(3) { background: #86efac; }

.kv-browser-url {
  font-size: 0.72rem;
  color: var(--kv-text-muted);
  background: #ffffff;
  border: 1px solid var(--kv-border);
  padding: 2px 12px;
  border-radius: 6px;
  max-width: 64%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.kv-browser-zoom {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--kv-brand);
  background: var(--kv-brand-soft);
  border: none;
  padding: 3px 8px;
  border-radius: 5px;
}

.kv-browser-img-wrap {
  position: relative;
  background: #f1f5f9;
  cursor: zoom-in;
}

.kv-browser-img-wrap img {
  width: 100%;
  aspect-ratio: 2878 / 1464;
  object-fit: cover;
  object-position: top left;
}

/* 右下悬浮真实桌面客户端框 */
.kv-client-float {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 34%;
  max-width: 215px;
  background: #0b1120;
  border: 1px solid rgba(56, 189, 248, 0.35);
  border-radius: 14px;
  box-shadow: var(--kv-shadow-dark);
  overflow: hidden;
  cursor: zoom-in;
  transition: transform var(--kv-transition), border-color var(--kv-transition);
}

.kv-client-float:hover {
  transform: translateY(-4px);
  border-color: #38bdf8;
}

.kv-client-float img {
  width: 100%;
  aspect-ratio: 820 / 1420;
  object-fit: cover;
}

.kv-client-caption {
  padding: 5px 10px;
  background: rgba(15, 23, 42, 0.96);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  color: #cbd5e1;
  font-size: 0.68rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* ==========================================================================
   通用 Section 结构与标题头
   ========================================================================== */
.kv-section {
  padding: 76px 0;
}

.kv-section-subtle {
  background: var(--kv-bg-subtle);
  border-top: 1px solid var(--kv-border);
  border-bottom: 1px solid var(--kv-border);
}

.kv-section-dark {
  background:
    radial-gradient(circle at 20% 0%, rgba(37, 99, 235, 0.16) 0%, transparent 50%),
    radial-gradient(circle at 85% 90%, rgba(14, 165, 233, 0.12) 0%, transparent 45%),
    var(--kv-bg-dark);
  color: var(--kv-text-inverse);
}

.kv-section-head {
  max-width: 760px;
  margin: 0 auto 48px;
  text-align: center;
}

.kv-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 4px 12px;
  border-radius: 999px;
  color: var(--kv-brand);
  background: var(--kv-brand-soft);
  border: 1px solid var(--kv-brand-border);
  margin-bottom: 14px;
}

.kv-section-dark .kv-eyebrow {
  color: #38bdf8;
  background: rgba(56, 189, 248, 0.12);
  border-color: rgba(56, 189, 248, 0.28);
}

.kv-section-title {
  font-size: clamp(1.65rem, 2.8vw, 2.35rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.25;
  margin: 0 0 14px;
}

.kv-section-sub {
  font-size: 1.02rem;
  color: var(--kv-text-muted);
  margin: 0;
  line-height: 1.7;
}

.kv-section-dark .kv-section-sub {
  color: var(--kv-text-inverse-muted);
}

/* ==========================================================================
   模块 1：解决什么问题 & 带来什么价值 (2x2 工程卡片)
   ========================================================================== */
.kv-grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px;
}

.kv-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.kv-grid-4 {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.kv-value-card {
  background: #ffffff;
  border: 1px solid var(--kv-border);
  border-radius: var(--kv-radius-lg);
  padding: 26px;
  box-shadow: var(--kv-shadow-xs);
  transition: transform var(--kv-transition), box-shadow var(--kv-transition), border-color var(--kv-transition);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.kv-value-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--kv-shadow-md);
  border-color: rgba(37, 99, 235, 0.35);
}

.kv-vc-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.kv-vc-icon {
  width: 44px;
  height: 44px;
  border-radius: 11px;
  background: var(--kv-brand-soft);
  color: var(--kv-brand);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.kv-vc-pain {
  font-size: 0.78rem;
  font-weight: 600;
  color: #b91c1c;
  background: #fef2f2;
  border: 1px solid #fecaca;
  padding: 3px 10px;
  border-radius: 999px;
}

.kv-vc-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--kv-text-primary);
  margin: 0;
}

.kv-vc-desc {
  font-size: 0.9375rem;
  color: var(--kv-text-secondary);
  margin: 0;
  line-height: 1.65;
}

.kv-vc-result {
  margin-top: auto;
  padding-top: 12px;
  border-top: 1px dashed var(--kv-border);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--kv-success);
  display: flex;
  align-items: flex-start;
  gap: 6px;
}

/* ==========================================================================
   模块 2：全套真实产品图鉴 (交互画廊 + 缩略条 + 灯箱放大)
   ========================================================================== */
.kv-gallery-tabs {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.kv-gtab-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 16px;
  border-radius: 999px;
  border: 1px solid var(--kv-border-strong);
  background: #ffffff;
  color: var(--kv-text-secondary);
  font-size: 0.875rem;
  font-weight: 600;
  transition: all var(--kv-transition);
  white-space: nowrap;
}

.kv-gtab-btn:hover {
  border-color: var(--kv-brand);
  color: var(--kv-brand);
}

.kv-gtab-btn.is-active {
  background: var(--kv-brand);
  border-color: var(--kv-brand);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.28);
}

.kv-gallery-stage {
  background: #ffffff;
  border: 1px solid var(--kv-border-strong);
  border-radius: var(--kv-radius-xl);
  box-shadow: var(--kv-shadow-md);
  overflow: hidden;
}

.kv-gallery-main {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(0, 0.95fr);
  align-items: stretch;
}

.kv-gallery-preview {
  position: relative;
  background: linear-gradient(150deg, #f1f5f9 0%, #f8fafc 100%);
  padding: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: zoom-in;
}

.kv-gallery-preview img {
  width: 100%;
  height: auto;
  max-height: 460px;
  border-radius: 10px;
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.08);
  border: 1px solid rgba(15, 23, 42, 0.08);
  object-fit: contain;
}

.kv-gallery-preview.is-portrait img {
  width: auto;
  max-width: 100%;
  max-height: 430px;
}

.kv-zoom-badge {
  position: absolute;
  right: 26px;
  bottom: 26px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(15, 23, 42, 0.84);
  backdrop-filter: blur(8px);
  color: #f8fafc;
  border: 1px solid rgba(255, 255, 255, 0.22);
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 600;
  pointer-events: none;
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.16);
}

.kv-gallery-aside {
  padding: 30px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 18px;
  background: #ffffff;
  border-left: 1px solid var(--kv-border);
}

.kv-ga-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--kv-brand);
  background: var(--kv-brand-soft);
  padding: 3px 10px;
  border-radius: 6px;
  margin-bottom: 10px;
}

.kv-ga-title {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--kv-text-primary);
  margin: 0 0 12px;
  line-height: 1.3;
}

.kv-ga-desc {
  font-size: 0.94rem;
  color: var(--kv-text-secondary);
  margin: 0 0 18px;
  line-height: 1.68;
}

.kv-ga-points {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.kv-ga-points li {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  font-size: 0.885rem;
  color: var(--kv-text-secondary);
}

.kv-ga-points svg {
  color: var(--kv-brand);
  flex-shrink: 0;
  margin-top: 3px;
}

.kv-gallery-thumbs {
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  gap: 10px;
  padding: 14px 18px;
  background: #f8fafc;
  border-top: 1px solid var(--kv-border);
}

.kv-thumb-btn {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 5px;
  border-radius: 8px;
  border: 2px solid transparent;
  background: #ffffff;
  text-align: left;
  transition: all var(--kv-transition);
}

.kv-thumb-btn:hover {
  border-color: var(--kv-border-strong);
}

.kv-thumb-btn.is-active {
  border-color: var(--kv-brand);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.14);
}

.kv-thumb-btn img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  object-position: top;
  border-radius: 4px;
  background: #e2e8f0;
}

.kv-thumb-btn span {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--kv-text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ==========================================================================
   模块 3：全链路溯源安全深度解析 (交互节点 + 真实取证字段解剖)
   ========================================================================== */
.kv-trace-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
  gap: 32px;
  align-items: stretch;
}

.kv-trace-steps {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.kv-trace-step {
  width: 100%;
  text-align: left;
  padding: 18px 20px;
  border-radius: var(--kv-radius-md);
  background: rgba(30, 41, 59, 0.55);
  border: 1px solid var(--kv-border-dark);
  color: var(--kv-text-inverse);
  transition: all var(--kv-transition);
  display: flex;
  gap: 14px;
  align-items: flex-start;
}

.kv-trace-step:hover {
  background: rgba(30, 41, 59, 0.9);
  border-color: rgba(56, 189, 248, 0.35);
}

.kv-trace-step.is-active {
  background: rgba(37, 99, 235, 0.18);
  border-color: #38bdf8;
  box-shadow: 0 8px 24px rgba(2, 132, 199, 0.22);
}

.kv-ts-num {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: rgba(56, 189, 248, 0.14);
  color: #38bdf8;
  font-weight: 700;
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.kv-trace-step.is-active .kv-ts-num {
  background: #38bdf8;
  color: #0b1120;
}

.kv-ts-body {
  display: block;
}

.kv-ts-title {
  display: block;
  font-size: 1rem;
  font-weight: 700;
  margin: 0 0 4px;
}

.kv-ts-desc {
  display: block;
  font-size: 0.875rem;
  color: var(--kv-text-inverse-muted);
  margin: 0;
  line-height: 1.55;
}

.kv-trace-outcome {
  background: #0f172a;
  border: 1px solid rgba(56, 189, 248, 0.25);
  border-radius: var(--kv-radius-lg);
  box-shadow: var(--kv-shadow-dark);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.kv-to-header {
  padding: 14px 20px;
  background: rgba(15, 23, 42, 0.95);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.kv-to-status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  font-weight: 700;
  color: #e2e8f0;
}

.kv-to-tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: #38bdf8;
  background: rgba(56, 189, 248, 0.14);
  border: 1px solid rgba(56, 189, 248, 0.3);
  padding: 3px 10px;
  border-radius: var(--kv-radius-pill);
}

.kv-to-body {
  padding: 22px;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.kv-to-heading {
  margin: 0;
  font-size: 1.18rem;
  font-weight: 800;
  color: #ffffff;
  line-height: 1.38;
}

.kv-to-compare {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.kv-to-box {
  padding: 13px 15px;
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.kv-to-box p {
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.6;
}

.kv-to-box.is-risk {
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.25);
  color: #fecaca;
}

.kv-to-box.is-safe {
  background: rgba(16, 185, 129, 0.1);
  border: 1px solid rgba(16, 185, 129, 0.28);
  color: #d1fae5;
}

.kv-to-box-label {
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  opacity: 0.92;
}

.kv-to-shot {
  position: relative;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.14);
  background: #f8fafc;
  cursor: zoom-in;
  transition: transform var(--kv-transition), border-color var(--kv-transition);
}

.kv-to-shot:hover {
  transform: translateY(-2px);
  border-color: #38bdf8;
}

.kv-to-shot img {
  width: 100%;
  aspect-ratio: 2878 / 1474;
  object-fit: cover;
  object-position: top left;
}

.kv-to-shot-bar {
  padding: 9px 14px;
  background: #1e293b;
  color: #e2e8f0;
  font-size: 0.8rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.kv-to-shot-zoom {
  color: #38bdf8;
  font-weight: 700;
  white-space: nowrap;
}

/* ==========================================================================
   模块 4：KeepVPN vs 传统 VPN (OpenVPN / 商业硬件 VPN 客观对比)
   ========================================================================== */
.kv-compare-wrap {
  background: #ffffff;
  border: 1px solid var(--kv-border-strong);
  border-radius: var(--kv-radius-lg);
  box-shadow: var(--kv-shadow-sm);
  overflow: hidden;
}

.kv-compare-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.kv-compare-table th,
.kv-compare-table td {
  padding: 16px 18px;
  border-bottom: 1px solid var(--kv-border);
  vertical-align: top;
  font-size: 0.92rem;
}

.kv-compare-table thead th {
  background: #f8fafc;
  font-weight: 700;
  color: var(--kv-text-primary);
  font-size: 0.94rem;
}

.kv-compare-table tbody tr:last-child td {
  border-bottom: none;
}

.kv-col-keepvpn {
  background: rgba(37, 99, 235, 0.035);
}

.kv-col-keepvpn strong {
  color: var(--kv-brand);
}

.kv-tag-good {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  background: var(--kv-success-soft);
  color: var(--kv-success);
  margin-bottom: 6px;
}

.kv-tag-legacy {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  background: #f1f5f9;
  color: #475569;
  margin-bottom: 6px;
}

/* 移动端友好卡片式对比（桌面隐藏，手机显示） */
.kv-compare-mobile {
  display: none;
}

/* ==========================================================================
   模块 5：完全免费 & 独立私有化部署架构
   ========================================================================== */
.kv-deploy-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1.15fr);
  gap: 28px;
  align-items: start;
}

.kv-free-pledge {
  background: #ffffff;
  border: 1px solid var(--kv-border-strong);
  border-radius: var(--kv-radius-lg);
  padding: 28px;
  box-shadow: var(--kv-shadow-sm);
}

.kv-pledge-list {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.kv-pledge-list li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  font-size: 0.93rem;
  color: var(--kv-text-secondary);
}

.kv-pledge-badge {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--kv-success-soft);
  color: var(--kv-success);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 1px;
}

.kv-github-card {
  background: linear-gradient(155deg, #0b1120 0%, #0f172a 100%);
  border: 1px solid #1e293b;
  border-radius: var(--kv-radius-lg);
  box-shadow: var(--kv-shadow-lg);
  overflow: hidden;
  color: #e2e8f0;
}

.kv-gh-top {
  padding: 13px 18px;
  background: rgba(17, 24, 39, 0.85);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.kv-gh-repo-meta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  font-weight: 700;
  color: #f8fafc;
}

.kv-copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.18);
  color: #f8fafc;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: 6px;
  transition: all var(--kv-transition);
}

.kv-copy-btn:hover {
  background: rgba(56, 189, 248, 0.22);
  border-color: #38bdf8;
}

.kv-gh-body {
  padding: 26px 28px 28px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.kv-gh-badge {
  align-self: flex-start;
  display: inline-block;
  padding: 3px 10px;
  border-radius: var(--kv-radius-pill);
  background: rgba(56, 189, 248, 0.14);
  border: 1px solid rgba(56, 189, 248, 0.32);
  color: #38bdf8;
  font-size: 0.75rem;
  font-weight: 700;
}

.kv-gh-title {
  margin: 0;
  font-size: 1.32rem;
  font-weight: 800;
  color: #ffffff;
  line-height: 1.35;
}

.kv-gh-desc {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.7;
  color: #94a3b8;
}

.kv-gh-highlights {
  list-style: none;
  margin: 2px 0;
  padding: 14px 16px;
  border-radius: var(--kv-radius-md);
  background: rgba(255, 255, 255, 0.035);
  border: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  flex-direction: column;
  gap: 11px;
}

.kv-gh-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.88rem;
  line-height: 1.55;
  color: #cbd5e1;
}

.kv-gh-item strong {
  color: #f8fafc;
}

.kv-gh-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #38bdf8;
  box-shadow: 0 0 8px rgba(56, 189, 248, 0.7);
  flex-shrink: 0;
  margin-top: 7px;
}

.kv-gh-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding-top: 4px;
}

.kv-gh-cta {
  width: 100%;
}

.kv-gh-url {
  text-align: center;
  font-size: 0.8rem;
  color: #64748b;
  word-break: break-all;
}

/* ==========================================================================
   模块 6：全平台终端生态与客户端入口
   ========================================================================== */
.kv-os-card {
  background: #ffffff;
  border: 1px solid var(--kv-border);
  border-radius: var(--kv-radius-lg);
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 14px;
  transition: all var(--kv-transition);
}

.kv-os-card.is-recommended {
  border-color: var(--kv-brand);
  box-shadow: 0 8px 26px -6px rgba(37, 99, 235, 0.2);
}

.kv-os-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.kv-os-title-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
}

.kv-os-icon {
  width: 38px;
  height: 38px;
  border-radius: 9px;
  background: var(--kv-bg-muted);
  color: var(--kv-text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.kv-os-card.is-recommended .kv-os-icon {
  background: var(--kv-brand-soft);
  color: var(--kv-brand);
}

.kv-os-badge {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--kv-brand);
  color: #ffffff;
}

/* ==========================================================================
   模块 7：FAQ 手风琴
   ========================================================================== */
.kv-faq-list {
  max-width: 860px;
  margin-inline: auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.kv-faq-item {
  background: #ffffff;
  border: 1px solid var(--kv-border);
  border-radius: var(--kv-radius-md);
  overflow: hidden;
  transition: border-color var(--kv-transition);
}

.kv-faq-item.is-open {
  border-color: var(--kv-brand-border);
  box-shadow: var(--kv-shadow-xs);
}

.kv-faq-q {
  width: 100%;
  background: transparent;
  border: none;
  padding: 18px 20px;
  text-align: left;
  font-size: 1rem;
  font-weight: 700;
  color: var(--kv-text-primary);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.kv-faq-chevron {
  transition: transform var(--kv-transition);
  color: var(--kv-text-muted);
  flex-shrink: 0;
}

.kv-faq-item.is-open .kv-faq-chevron {
  transform: rotate(180deg);
  color: var(--kv-brand);
}

.kv-faq-a {
  display: none;
  padding: 0 20px 18px;
  font-size: 0.9375rem;
  color: var(--kv-text-secondary);
  line-height: 1.7;
}

.kv-faq-item.is-open .kv-faq-a {
  display: block;
}

/* ==========================================================================
   底部号召栏 & Footer
   ========================================================================== */
.kv-cta-banner {
  background:
    radial-gradient(circle at 80% 20%, rgba(56, 189, 248, 0.22) 0%, transparent 48%),
    linear-gradient(135deg, #0f172a 0%, #1e3a8a 100%);
  color: #ffffff;
  padding: 68px 0;
  text-align: center;
}

.kv-footer {
  background: #ffffff;
  border-top: 1px solid var(--kv-border);
  padding: 36px 0;
  font-size: 0.875rem;
  color: var(--kv-text-muted);
}

.kv-footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.kv-footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

.kv-footer-links a:hover {
  color: var(--kv-brand);
}

/* ==========================================================================
   高清产品大图灯箱弹窗 (Lightbox Modal) & Toast
   ========================================================================== */
.kv-lightbox {
  position: fixed;
  inset: 0;
  z-index: 2000;
  background: rgba(2, 6, 23, 0.88);
  backdrop-filter: blur(8px);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.kv-lightbox.is-open {
  display: flex;
}

.kv-lb-topbar {
  width: 100%;
  max-width: 1180px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: #f8fafc;
  margin-bottom: 12px;
}

.kv-lb-close {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.08);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
}

.kv-lb-stage {
  position: relative;
  width: 100%;
  max-width: 1180px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.kv-lb-stage img {
  max-width: calc(100% - 108px);
  max-height: 76vh;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.6);
  object-fit: contain;
}

.kv-lb-nav {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.22);
  background: rgba(15, 23, 42, 0.78);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 1.35rem;
}

.kv-lb-nav:hover,
.kv-lb-close:hover {
  background: var(--kv-brand);
  border-color: var(--kv-brand);
}

.kv-lb-caption {
  margin-top: 14px;
  max-width: 820px;
  text-align: center;
  color: #cbd5e1;
  font-size: 0.92rem;
}

.kv-toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%) translateY(16px);
  background: #0f172a;
  color: #f8fafc;
  border: 1px solid rgba(56, 189, 248, 0.35);
  padding: 10px 18px;
  border-radius: 10px;
  box-shadow: var(--kv-shadow-lg);
  font-size: 0.875rem;
  font-weight: 500;
  z-index: 2500;
  opacity: 0;
  pointer-events: none;
  transition: all 0.24s ease;
  max-width: calc(100vw - 32px);
  text-align: center;
}

.kv-toast.is-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ==========================================================================
   平板端响应式适配 (768px ~ 1120px)
   ========================================================================== */
@media (max-width: 1120px) {
  .kv-hero-grid {
    grid-template-columns: 1fr;
    gap: 34px;
  }

  .kv-hero-content {
    text-align: center;
  }

  .kv-hero-desc {
    margin-inline: auto;
  }

  .kv-hero-cta {
    justify-content: center;
  }

  .kv-hero-facts {
    max-width: 620px;
    margin-inline: auto;
    text-align: left;
  }

  .kv-hero-stage {
    max-width: 780px;
    margin-inline: auto;
  }

  .kv-gallery-main {
    grid-template-columns: 1fr;
  }

  .kv-gallery-aside {
    border-left: none;
    border-top: 1px solid var(--kv-border);
  }

  .kv-trace-layout,
  .kv-deploy-grid {
    grid-template-columns: 1fr;
  }

  .kv-grid-3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .kv-grid-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* ==========================================================================
   平板竖屏 & 折叠导航阈值 (< 992px)
   ========================================================================== */
@media (max-width: 991.98px) {
  .kv-mobile-toggle {
    display: inline-flex;
  }

  .kv-nav-collapse {
    position: fixed;
    top: var(--kv-nav-height);
    left: 0;
    right: 0;
    background: #ffffff;
    border-bottom: 1px solid var(--kv-border);
    box-shadow: var(--kv-shadow-md);
    padding: 16px 20px 20px;
    display: none;
    flex-direction: column;
    gap: 14px;
    z-index: 890;
  }

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

  .kv-nav-links {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
  }

  .kv-nav-link {
    padding: 11px 14px;
    font-size: 1rem;
  }

  .kv-nav-actions {
    width: 100%;
    flex-direction: column;
  }

  .kv-nav-actions .kv-btn {
    width: 100%;
  }

  .kv-gallery-thumbs {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 992px) {
  .kv-nav-collapse {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex: 1;
    gap: 16px;
  }
}

/* ==========================================================================
   移动端专属精细适配 (< 767.98px)
   ========================================================================== */
@media (max-width: 767.98px) {
  :root {
    --kv-nav-height: 62px;
  }

  .kv-container {
    padding-inline: 16px;
  }

  .kv-top-notice {
    display: none;
  }

  .kv-brand-tag {
    display: none;
  }

  .kv-hero {
    padding: 36px 0 48px;
  }

  .kv-hero-content {
    text-align: left;
  }

  .kv-hero-cta {
    justify-content: stretch;
  }

  .kv-hero-cta .kv-btn {
    width: 100%;
    min-height: 46px;
  }

  .kv-hero-facts {
    grid-template-columns: 1fr;
  }

  /* 移动端取消桌面端右下角压盖叠放，转为双端清晰并列展示 */
  .kv-hero-stage {
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 14px;
  }

  .kv-client-float {
    position: static;
    width: 68%;
    max-width: 240px;
    margin-inline: auto;
  }

  .kv-section {
    padding: 52px 0;
  }

  .kv-section-head {
    margin-bottom: 32px;
    text-align: left;
  }

  .kv-grid-2,
  .kv-grid-3,
  .kv-grid-4,
  .kv-to-compare {
    grid-template-columns: 1fr;
  }

  /* 移动端横滑画廊选项卡：单手顺滑切换不折行堆叠 */
  .kv-gallery-tabs {
    flex-wrap: nowrap;
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 6px;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

  .kv-gallery-tabs::-webkit-scrollbar {
    display: none;
  }

  .kv-gallery-preview {
    padding: 10px;
  }

  .kv-gallery-aside {
    padding: 20px 18px;
  }

  .kv-gallery-thumbs {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 8px;
    padding: 10px 12px;
  }

  /* 移动端用卡片代替宽表格，彻底消灭横向拖表 */
  .kv-compare-wrap {
    display: none;
  }

  .kv-compare-mobile {
    display: flex;
    flex-direction: column;
    gap: 14px;
  }

  .kv-cm-card {
    background: #ffffff;
    border: 1px solid var(--kv-border-strong);
    border-radius: var(--kv-radius-md);
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 10px;
  }

  .kv-cm-dim {
    font-size: 0.98rem;
    font-weight: 800;
    color: var(--kv-text-primary);
    border-bottom: 1px solid var(--kv-border);
    padding-bottom: 8px;
  }

  .kv-cm-row {
    display: flex;
    flex-direction: column;
    gap: 3px;
    padding: 9px 11px;
    border-radius: 8px;
    font-size: 0.875rem;
  }

  .kv-cm-row.is-keepvpn {
    background: rgba(37, 99, 235, 0.06);
    border: 1px solid rgba(37, 99, 235, 0.2);
  }

  .kv-cm-row.is-legacy {
    background: #f8fafc;
    border: 1px solid var(--kv-border);
    color: var(--kv-text-secondary);
  }

  .kv-gh-body {
    padding: 22px 18px;
  }

  .kv-lb-stage img {
    max-width: 100%;
    max-height: 64vh;
  }

  .kv-lb-nav {
    position: absolute;
    bottom: -58px;
  }

  .kv-lb-prev { left: calc(50% - 56px); }
  .kv-lb-next { right: calc(50% - 56px); }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}