:root {
  --bg-color: #f8fafc;
  --text-primary: #0f172b;
  --text-secondary: #45556c;
  --text-muted: #90a1b9;
  --accent-color: #00b8db;
  --accent-hover: #00d3f3;
  --card-bg: rgba(255, 255, 255, 0.8);
  --card-border: rgba(226, 232, 240, 1);
  --header-bg: rgba(255, 255, 255, 0.6);
  --header-border: rgba(226, 232, 240, 0.5);
  --nav-link: #62748e;
  --nav-link-hover: #0f172b;
  --btn-primary-bg: #00b8db;
  --btn-primary-text: #ffffff;
  --btn-secondary-bg: #f1f5f9;
  --btn-secondary-text: #1d293d;
  --btn-secondary-border: #e2e8f0;
  --pricing-bg: #ffffff;
  --pricing-border: #e2e8f0;
  --pricing-active-bg: #ecfeffcc;
  --pricing-active-border: #a2f4fd;
  --tag-bg: rgba(0, 184, 219, 0.1);
  --tag-text: #0092b8;
  --glow-1: rgba(83, 234, 253, 0.3);
  --glow-2: rgba(163, 179, 255, 0.3);
  --gradient-line: linear-gradient(90deg, #00d3f3 0%, #7c86ff 100%);
  --theme-icon: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="%230f172b" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z"></path></svg>');
  --transition: all 0.3s ease;
}

[data-theme="dark"] {
  --bg-color: #020618;
  --text-primary: #ffffff;
  --text-secondary: #90a1b9;
  --text-muted: #62748e;
  --accent-color: #00b8db;
  --accent-hover: #00d3f3;
  --card-bg: rgba(15, 23, 43, 0.9);
  --card-border: #314158;
  --header-bg: rgba(2, 6, 24, 0.6);
  --header-border: rgba(255, 255, 255, 0.05);
  --nav-link: #90a1b9;
  --nav-link-hover: #ffffff;
  --btn-primary-bg: #00b8db;
  --btn-primary-text: #ffffff;
  --btn-secondary-bg: rgba(255, 255, 255, 0.05);
  --btn-secondary-text: #ffffff;
  --btn-secondary-border: rgba(255, 255, 255, 0.1);
  --pricing-bg: rgba(15, 23, 43, 0.9);
  --pricing-border: rgba(49, 65, 88, 0.5);
  --pricing-active-bg: rgba(5, 51, 69, 0.3);
  --pricing-active-border: rgba(16, 78, 100, 0.5);
  --tag-bg: rgba(0, 211, 243, 0.1);
  --tag-text: #00d3f3;
  --glow-1: rgba(16, 78, 100, 0.2);
  --glow-2: rgba(49, 44, 133, 0.2);
  --gradient-line: linear-gradient(90deg, #00b8db 0%, #615fff 100%);
  --theme-icon: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="%23ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="5"></circle><line x1="12" y1="1" x2="12" y2="3"></line><line x1="12" y1="21" x2="12" y2="23"></line><line x1="4.22" y1="4.22" x2="5.64" y2="5.64"></line><line x1="18.36" y1="18.36" x2="19.78" y2="19.78"></line><line x1="1" y1="12" x2="3" y2="12"></line><line x1="21" y1="12" x2="23" y2="12"></line><line x1="4.22" y1="19.78" x2="5.64" y2="18.36"></line><line x1="18.36" y1="5.64" x2="19.78" y2="4.22"></line></svg>');
}

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

body {
  font-family: Inter, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.5;
  overflow-x: hidden;
  transition: background-color 0.3s ease, color 0.3s ease;
}

input,
textarea,
select {
  font-size: 16px;
}

a { text-decoration: none; color: inherit; transition: var(--transition); }
ul { list-style: none; }

/* Canvas Background */
#particles-js {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  pointer-events: none;
}

/* Glow Backgrounds */
.glow-container {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  z-index: -2;
  overflow: hidden;
  pointer-events: none;
}
.glow-1 {
  position: absolute;
  top: -10%; left: 10%;
  width: 60vw; height: 60vw;
  background: var(--glow-1);
  filter: blur(120px);
  border-radius: 50%;
  transition: var(--transition);
}
.glow-2 {
  position: absolute;
  top: 20%; right: -10%;
  width: 50vw; height: 50vw;
  background: var(--glow-2);
  filter: blur(120px);
  border-radius: 50%;
  transition: var(--transition);
}

.shell {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  position: fixed;
  top: 0; left: 0; right: 0;
  background: var(--header-bg);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--header-border);
  z-index: 100;
}
.logo-area { display: flex; align-items: center; gap: 8px; }
.logo-text { font-size: 20px; font-weight: 700; color: var(--text-primary); letter-spacing: -0.5px; }
.beta-tag { 
  background: var(--tag-bg); color: var(--tag-text); 
  font-size: 12px; padding: 2px 8px; border-radius: 12px; font-weight: 500;
}

.nav-links { display: flex; gap: 32px; align-items: center; }
.nav-link { color: var(--nav-link); font-size: 14px; font-weight: 500; transition: var(--transition); }
.nav-link:hover { color: var(--nav-link-hover); }

.header-actions { display: flex; align-items: center; gap: 16px; }
.theme-toggle {
  width: 36px; height: 36px;
  border-radius: 50%;
  background: var(--btn-secondary-bg);
  border: 1px solid var(--btn-secondary-border);
  display: flex; align-items: center; justify-content: center;
  cursor: pointer; transition: var(--transition);
}
.theme-toggle i {
  display: block; width: 16px; height: 16px;
  background-image: var(--theme-icon);
  background-size: cover;
}
.theme-toggle:hover { background: var(--btn-secondary-border); }

.btn-primary {
  background: var(--btn-primary-bg); color: var(--btn-primary-text);
  padding: 10px 20px; border-radius: 99px; font-size: 14px; font-weight: 500;
  display: inline-flex; align-items: center; justify-content: center;
  border: none; cursor: pointer; transition: var(--transition);
}
.btn-primary:hover { opacity: 0.9; transform: translateY(-1px); box-shadow: 0 4px 12px rgba(0,184,219,0.3); }

.btn-secondary {
  background: var(--btn-secondary-bg); color: var(--btn-secondary-text);
  border: 1px solid var(--btn-secondary-border);
  padding: 10px 20px; border-radius: 99px; font-size: 14px; font-weight: 500;
  display: inline-flex; align-items: center; justify-content: center;
  cursor: pointer; transition: var(--transition);
}
.btn-secondary:hover { background: var(--btn-secondary-border); }

/* Hero */
.hero {
  padding-top: 160px;
  display: flex; flex-direction: column; align-items: center; text-align: center;
  margin-bottom: 80px;
}
.hero-tag {
  background: var(--tag-bg); color: var(--tag-text);
  padding: 6px 16px; border-radius: 20px; font-size: 14px; font-weight: 500;
  margin-bottom: 24px; border: 1px solid rgba(0, 184, 219, 0.2);
}
.hero h1 {
  font-size: 64px; font-weight: 800; letter-spacing: -1.5px;
  margin-bottom: 24px; line-height: 1.1;
}
.hero h1 span { color: var(--accent-color); }
.hero p.desc {
  font-size: 18px; color: var(--text-secondary); max-width: 600px;
  margin: 0 auto 40px; line-height: 1.6;
}
.hero-actions { display: flex; gap: 16px; justify-content: center; margin-bottom: 80px; }
.hero-actions .btn-primary, .hero-actions .btn-secondary { padding: 14px 32px; font-size: 16px; }

.hero-image-wrapper {
  position: relative; width: 100%; max-width: 900px; margin: 0 auto;
}
.hero-image {
  width: 100%; border-radius: 24px; box-shadow: 0 24px 50px rgba(0,0,0,0.1);
  display: block; position: relative; z-index: 2;
  border: 1px solid var(--btn-secondary-border);
}
.hero-image-glow {
  position: absolute; top: 10%; left: 5%; right: 5%; bottom: -10%;
  background: var(--gradient-line);
  filter: blur(40px); opacity: 0.3; z-index: 1; border-radius: 40px;
}

/* Features Grid */
.features-4 {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
  margin-top: 60px; max-width: 1100px; margin-left: auto; margin-right: auto;
  text-align: left;
}
.feature-item h4 { color: var(--accent-color); font-size: 18px; margin-bottom: 8px; font-weight: 700; }
.feature-item p { color: var(--text-secondary); font-size: 14px; line-height: 1.6; }

/* Section 2 */
.section { padding: 100px 0; text-align: center; }
.section-subtitle { color: var(--text-primary); font-size: 32px; font-weight: 700; margin-bottom: 16px; }
.section-title { color: var(--accent-color); font-size: 14px; text-transform: uppercase; letter-spacing: 1px; margin-bottom: 8px; font-weight: 600; }

.feature-cards {
  display: grid; grid-template-columns: 1fr 1fr; gap: 24px;
  max-width: 900px; margin: 40px auto 0;
}
.f-card {
  background: var(--btn-secondary-bg); border: 1px solid var(--btn-secondary-border);
  border-radius: 24px; padding: 40px; text-align: left;
  display: flex; flex-direction: column; justify-content: flex-end;
  min-height: 240px; position: relative; overflow: hidden;
}
.f-card h3 { font-size: 24px; margin-bottom: 12px; color: var(--text-primary); font-weight: 700; }
.f-card p { font-size: 16px; color: var(--text-secondary); line-height: 1.5; }
.f-card.full-width { grid-column: 1 / -1; align-items: center; text-align: center; background: var(--btn-secondary-bg); justify-content: center; }
.f-card.full-width p { max-width: 600px; }

/* Pricing */
.pricing-desc { color: var(--text-secondary); font-size: 16px; margin-bottom: 40px; }
.pricing-cards {
  display: grid; grid-template-columns: 1fr 1fr; gap: 24px;
  max-width: 800px; margin: 0 auto; text-align: left;
}
.p-card {
  background: var(--pricing-bg); border: 1px solid var(--pricing-border);
  border-radius: 24px; padding: 40px; position: relative;
  transition: var(--transition);
}
.p-card.active {
  background: var(--pricing-active-bg); border-color: var(--pricing-active-border);
}
.p-badge {
  position: absolute; top: -12px; left: 40px;
  background: var(--accent-color); color: #fff; font-size: 12px; font-weight: 700;
  padding: 4px 12px; border-radius: 8px;
}
.p-title { font-size: 24px; font-weight: 600; margin-bottom: 8px; color: var(--text-primary); }
.p-desc { font-size: 14px; color: var(--text-secondary); margin-bottom: 24px; min-height: 42px; }
.p-price { font-size: 40px; font-weight: 700; color: var(--text-primary); margin-bottom: 24px; display: flex; align-items: baseline; gap: 4px; }
.p-price span { font-size: 16px; color: var(--text-secondary); font-weight: 400; }
.p-yearly {
  display: flex; justify-content: space-between; align-items: center;
  background: var(--btn-secondary-bg); border: 1px solid var(--btn-secondary-border);
  padding: 12px 16px; border-radius: 12px; margin-bottom: 24px;
}
.p-yearly-price { font-size: 16px; font-weight: 600; color: var(--text-primary); }
.p-save { color: var(--accent-color); font-size: 14px; font-weight: 500; }
.p-card .btn-primary, .p-card .btn-secondary { width: 100%; padding: 14px; font-size: 16px; }

/* FAQ */
.faq-list {
  display: flex; flex-direction: column; gap: 24px; max-width: 800px; margin: 40px auto 0; text-align: left;
}
.faq-item {
  padding-bottom: 24px; border-bottom: 1px solid var(--btn-secondary-border);
}
.faq-item h4 { font-size: 18px; color: var(--text-primary); margin-bottom: 12px; font-weight: 600; }
.faq-item p { font-size: 16px; color: var(--text-secondary); line-height: 1.6; }

/* Footer */
.footer {
  border-top: 1px solid var(--header-border);
  padding: 40px 24px; margin-top: 60px;
  background: var(--header-bg);
}
.footer-content {
  max-width: 1280px; margin: 0 auto;
  display: flex; justify-content: space-between; align-items: flex-start;
}
.f-logo { font-size: 20px; font-weight: 700; color: var(--text-primary); margin-bottom: 8px; }
.f-desc { font-size: 14px; color: var(--text-secondary); margin-bottom: 16px; }
.f-icp { font-size: 12px; color: var(--text-muted); }
.f-links { display: flex; gap: 32px; align-items: center; }
.f-link { font-size: 14px; color: var(--text-secondary); font-weight: 500; transition: var(--transition); }
.f-link:hover { color: var(--text-primary); }

@media (max-width: 768px) {
  .hero { padding-top: 100px; }
  .hero h1 { font-size: 36px; letter-spacing: -0.5px; }
  .hero p.desc { font-size: 16px; padding: 0 16px; }
  .features-4 { grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 40px; padding: 0 16px; }
  .feature-cards { grid-template-columns: 1fr; gap: 16px; padding: 0 16px; }
  .f-card { padding: 24px; min-height: auto; }
  .pricing-cards { grid-template-columns: 1fr; gap: 16px; padding: 0 16px; }
  .footer-content { flex-direction: column; gap: 24px; align-items: flex-start; }
  .f-links { flex-wrap: wrap; gap: 16px; }
  .section { padding: 60px 0; }
  .section-subtitle { font-size: 24px; padding: 0 16px; }
  .pricing-desc { padding: 0 16px; }
  .faq-list { padding: 0 16px; }
}
@media (max-width: 480px) {
  .site-header { padding: 12px 16px; flex-wrap: wrap; }
  .logo-text { font-size: 18px; }
  .nav-links.has-links { width: 100%; justify-content: center; gap: 16px; margin-top: 8px; display: none; } /* Mobile Menu implementation */
  .nav-links > a.nav-link { display: inline-block; font-size: 13px; }
  .header-actions .btn-primary { display: none !important; }
  .header-actions { position: absolute; right: 16px; top: 12px; }
  .mobile-menu-btn { display: block; background: transparent; border: none; color: var(--text-primary); margin-right: 12px; }
  .nav-links.has-links.show { display: flex; flex-direction: column; width: 100%; text-align: center; padding: 16px 0; background: var(--card-bg); border-radius: 12px; margin-top: 16px; box-shadow: 0 4px 12px rgba(0,0,0,0.1); }
  .nav-links.has-links.show > a.nav-link { padding: 12px 0; font-size: 16px; width: 100%; border-bottom: 1px solid var(--btn-secondary-border); }
  .nav-links.has-links.show > a.nav-link:last-child { border-bottom: none; }
  
  .hero { padding-top: 80px; margin-bottom: 40px; }
  .hero h1 { font-size: 32px; }
  .features-4 { grid-template-columns: 1fr; }
  .hero-actions { flex-direction: column; width: 100%; padding: 0 24px; gap: 12px; }
  .hero-actions .btn-primary, .hero-actions .btn-secondary { width: 100%; }
  
  .hero-image-wrapper { padding: 0 16px; }
  .hero-image { border-radius: 12px; }
  .hero-image-glow { filter: blur(20px); }
  
  .p-card { padding: 24px; }
}