/* ===================================
   比特浏览器 - 深空护盾暗色主题
   =================================== */

/* -- CSS 变量 -- */
:root {
  --bg-base: #0B0F1A;
  --bg-surface: #131825;
  --bg-elevated: #1A2035;
  --accent: #00D4AA;
  --accent-dim: rgba(0, 212, 170, 0.12);
  --highlight: #F59E0B;
  --highlight-dim: rgba(245, 158, 11, 0.12);
  --text-primary: #E8ECF4;
  --text-secondary: #8892A7;
  --text-muted: #5A6478;
  --border: rgba(136, 146, 167, 0.12);
  --font-heading: 'DM Sans', sans-serif;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --max-w: 1180px;
  --nav-h: 64px;
}

/* -- 基础重置 -- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  background: var(--bg-base);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

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

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

ul {
  list-style: none;
}

/* -- 通用组件 -- */
.section-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 4px 10px;
  background: var(--accent-dim);
  border-radius: 4px;
  margin-bottom: 16px;
}

/* -- 滚动入场动画 -- */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===================================
   导航栏
   =================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-h);
  transition: background 0.3s, box-shadow 0.3s, backdrop-filter 0.3s;
}

.nav--scrolled {
  background: rgba(11, 15, 26, 0.82);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--border);
}

.nav__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 32px;
}

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

.nav__logo {
  width: 32px;
  height: 32px;
  border-radius: 6px;
}

.nav__name {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
}

.nav__menu {
  display: flex;
  align-items: center;
  gap: 28px;
  margin-left: auto;
}

.nav__link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color 0.2s;
  position: relative;
}

.nav__link:hover {
  color: var(--text-primary);
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: var(--accent);
  transition: width 0.2s;
}

.nav__link:hover::after {
  width: 100%;
}

.nav__cta {
  font-family: var(--font-heading);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--bg-base);
  background: var(--accent);
  padding: 8px 20px;
  border-radius: 6px;
  transition: opacity 0.2s, transform 0.15s;
  flex-shrink: 0;
}

.nav__cta:hover {
  opacity: 0.88;
  transform: translateY(-1px);
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav__toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: transform 0.3s, opacity 0.3s;
}

/* ===================================
   Hero 首屏
   =================================== */
.hero {
  position: relative;
  padding: calc(var(--nav-h) + 64px) 0 72px;
  overflow: hidden;
  min-height: 92vh;
  display: flex;
  align-items: center;
}

.hero__grid-bg {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(136, 146, 167, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(136, 146, 167, 0.04) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 70% 60% at 50% 40%, black 20%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 40%, black 20%, transparent 70%);
}

.hero__glow {
  position: absolute;
  top: -120px;
  right: -80px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(0, 212, 170, 0.1) 0%, transparent 65%);
  border-radius: 50%;
  animation: glowFloat 8s ease-in-out infinite;
  pointer-events: none;
}

@keyframes glowFloat {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(-30px, 20px) scale(1.05); }
  66% { transform: translate(15px, -25px) scale(0.97); }
}

.hero__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 48px;
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero__badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-dim);
  padding: 5px 12px;
  border-radius: 20px;
  margin-bottom: 20px;
}

.hero__title {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 4.2vw, 3.2rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
  margin-bottom: 20px;
}

.hero__title--accent {
  color: var(--accent);
}

.hero__subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 520px;
  margin-bottom: 32px;
}

.hero__download {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--bg-base);
  background: var(--accent);
  padding: 13px 28px;
  border-radius: 8px;
  transition: opacity 0.2s, transform 0.15s;
}

.hero__download:hover {
  opacity: 0.88;
  transform: translateY(-1px);
}

.hero__indicators {
  display: flex;
  gap: 28px;
  margin-top: 40px;
}

.hero__indicator {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.hero__indicator svg {
  stroke: var(--text-muted);
}

.hero__visual {
  position: relative;
}

.hero__screenshot-wrap {
  position: relative;
  transform: perspective(800px) rotateY(-4deg) rotateX(2deg);
  transition: transform 0.4s ease;
}

.hero__screenshot-wrap:hover {
  transform: perspective(800px) rotateY(-1deg) rotateX(0.5deg);
}

.hero__screenshot {
  border-radius: 12px;
  box-shadow:
    0 8px 32px rgba(0, 0, 0, 0.4),
    0 0 80px rgba(0, 212, 170, 0.08);
}

/* ===================================
   信任指标条
   =================================== */
.trust {
  padding: 56px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.trust__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.trust__item {
  text-align: center;
}

.trust__number {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.8rem, 3vw, 2.4rem);
  font-weight: 700;
  color: var(--highlight);
  line-height: 1.2;
  margin-bottom: 6px;
}

.trust__label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

/* ===================================
   核心能力
   =================================== */
.features {
  padding: 96px 0;
}

.features__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.features__header {
  max-width: 480px;
  margin-bottom: 56px;
}

.features__title {
  font-family: var(--font-heading);
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 14px;
}

.features__desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.features__grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  column-gap: 16px;
  row-gap: 20px;
}

.features__card {
  background: var(--bg-surface);
  border-radius: 8px;
  padding: 28px 28px 28px 31px;
  border-left: 3px solid var(--card-accent, var(--accent));
  transition: transform 0.25s, background 0.25s, border-left-width 0.15s;
  position: relative;
}

.features__card:hover {
  transform: translateY(-2px);
  background: var(--bg-elevated);
  border-left-width: 4px;
}

.features__card-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.04);
  border-radius: 8px;
  margin-bottom: 16px;
}

.features__card-title {
  font-family: var(--font-heading);
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.features__card-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

/* ===================================
   功能详解
   =================================== */
.showcase {
  padding: 48px 0 96px;
}

.showcase__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.showcase__block {
  display: grid;
  grid-template-columns: 0.55fr 0.45fr;
  gap: 56px;
  align-items: center;
  margin-bottom: 96px;
}

.showcase__block:last-child {
  margin-bottom: 0;
}

.showcase__block--reverse {
  grid-template-columns: 0.45fr 0.55fr;
}

.showcase__block--reverse .showcase__text {
  order: 2;
}

.showcase__block--reverse .showcase__media {
  order: 1;
}

.showcase__tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--tag-color, var(--accent));
  background: color-mix(in srgb, var(--tag-color, var(--accent)) 12%, transparent);
  padding: 4px 10px;
  border-radius: 4px;
  margin-bottom: 16px;
}

.showcase__heading {
  font-family: var(--font-heading);
  font-size: clamp(1.4rem, 2.6vw, 1.9rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 16px;
}

.showcase__desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 24px;
}

.showcase__list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.showcase__list li {
  font-size: 0.875rem;
  color: var(--text-secondary);
  padding-left: 20px;
  position: relative;
}

.showcase__list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 7px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

.showcase__metrics {
  display: flex;
  gap: 40px;
}

.showcase__metric-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--highlight);
  line-height: 1.2;
}

.showcase__metric-label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.showcase__techs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.showcase__tech {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
  background: var(--bg-elevated);
  padding: 5px 12px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

.showcase__img {
  border-radius: 10px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
}

/* ===================================
   数据安全
   =================================== */
.security {
  padding: 0 0 96px;
  position: relative;
}

.security__divider {
  height: 2px;
  background: linear-gradient(90deg, transparent 5%, var(--accent) 50%, transparent 95%);
  opacity: 0.25;
  margin-bottom: 80px;
}

.security__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 0.55fr 0.45fr;
  gap: 56px;
  align-items: center;
}

.security__title {
  font-family: var(--font-heading);
  font-size: clamp(1.4rem, 2.6vw, 1.9rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 14px;
}

.security__desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 32px;
}

.security__features {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.security__feat {
  display: flex;
  gap: 14px;
  align-items: flex-start;
}

.security__feat-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-dim);
  border-radius: 8px;
  flex-shrink: 0;
}

.security__feat-title {
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: 600;
  margin-bottom: 3px;
}

.security__feat-desc {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.security__img {
  border-radius: 10px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
}

/* ===================================
   快速开始
   =================================== */
.quickstart {
  padding: 80px 0 48px;
}

.quickstart__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.quickstart__title {
  font-family: var(--font-heading);
  font-size: clamp(1.4rem, 2.6vw, 1.9rem);
  font-weight: 700;
  margin-bottom: 48px;
}

.quickstart__steps {
  display: flex;
  align-items: flex-start;
  gap: 0;
}

.quickstart__step {
  flex: 1;
}

.quickstart__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent);
  opacity: 0.35;
  margin-bottom: 14px;
}

.quickstart__step-title {
  font-family: var(--font-heading);
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.quickstart__step-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.65;
  max-width: 260px;
}

.quickstart__arrow {
  flex-shrink: 0;
  padding-top: 14px;
  display: flex;
  align-items: center;
}

/* ===================================
   CTA
   =================================== */
.cta {
  padding: 64px 0 80px;
  position: relative;
}

.cta__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.cta__title {
  font-family: var(--font-heading);
  font-size: clamp(1.4rem, 2.6vw, 1.9rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 14px;
}

.cta__desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  margin-bottom: 28px;
}

.cta__button {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--bg-base);
  background: var(--accent);
  padding: 14px 32px;
  border-radius: 8px;
  transition: opacity 0.2s, transform 0.15s;
}

.cta__button:hover {
  opacity: 0.88;
  transform: translateY(-1px);
}

.cta__line {
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 320px;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), var(--highlight));
  border-radius: 1px;
  opacity: 0.5;
}

/* ===================================
   响应式
   =================================== */

/* 平板 */
@media (max-width: 900px) {
  .hero__inner {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
  }

  .hero__subtitle {
    margin-left: auto;
    margin-right: auto;
  }

  .hero__indicators {
    justify-content: center;
  }

  .hero__screenshot-wrap {
    transform: none;
    max-width: 520px;
    margin: 0 auto;
  }

  .hero__screenshot-wrap:hover {
    transform: none;
  }

  .trust__inner {
    grid-template-columns: repeat(2, 1fr);
    row-gap: 32px;
  }

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

  .showcase__block,
  .showcase__block--reverse {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .showcase__block--reverse .showcase__text {
    order: 1;
  }

  .showcase__block--reverse .showcase__media {
    order: 2;
  }

  .security__inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .quickstart__steps {
    flex-direction: column;
    gap: 24px;
  }

  .quickstart__arrow {
    transform: rotate(90deg);
    padding: 0;
  }
}

/* 手机 */
@media (max-width: 640px) {
  :root {
    --nav-h: 56px;
  }

  .nav__menu {
    position: fixed;
    top: var(--nav-h);
    left: 0;
    right: 0;
    background: rgba(19, 24, 37, 0.97);
    backdrop-filter: blur(16px);
    flex-direction: column;
    padding: 20px 24px;
    gap: 16px;
    transform: translateY(-120%);
    transition: transform 0.3s ease;
    border-bottom: 1px solid var(--border);
  }

  .nav--open .nav__menu {
    transform: translateY(0);
  }

  .nav__toggle {
    display: flex;
    margin-left: auto;
  }

  .nav--open .nav__toggle span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }

  .nav--open .nav__toggle span:nth-child(2) {
    opacity: 0;
  }

  .nav--open .nav__toggle span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }

  .nav__cta {
    display: none;
  }

  .hero {
    padding-top: calc(var(--nav-h) + 40px);
    min-height: auto;
  }

  .hero__title {
    font-size: 1.8rem;
  }

  .hero__indicators {
    flex-direction: column;
    gap: 12px;
    align-items: center;
  }

  .trust__inner {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .features,
  .showcase,
  .security,
  .quickstart,
  .cta {
    padding-top: 64px;
    padding-bottom: 64px;
  }

  .showcase__block {
    margin-bottom: 64px;
  }

  .showcase__metrics {
    gap: 24px;
  }

  .cta__line {
    width: 200px;
  }
}