/* =========================================
   Beaver Innovation - Design System
   深圳海狸创科 设计系统
   ========================================= */

:root {
  /* Brand Colors - 深蓝/银灰/白 科技配色 */
  --color-bg-primary: #050B1A;
  --color-bg-secondary: #0A1428;
  --color-bg-tertiary: #0F1B33;
  --color-bg-card: rgba(15, 27, 51, 0.6);
  --color-bg-card-hover: rgba(20, 35, 65, 0.8);

  --color-blue-deep: #0A1F4E;
  --color-blue-primary: #1E5BFF;
  --color-blue-bright: #4E8BFF;
  --color-blue-glow: #6FB6FF;
  --color-cyan: #00E0FF;

  --color-silver: #B8C5D6;
  --color-gray-light: #D8E1ED;
  --color-gray-mid: #6B7A92;
  --color-gray-dark: #2A3550;

  --color-white: #FFFFFF;
  --color-text-primary: #FFFFFF;
  --color-text-secondary: #B8C5D6;
  --color-text-muted: #6B7A92;

  --color-accent-warm: #FFB663; /* 教育温度感 */
  --color-success: #00D9A3;
  --color-border: rgba(110, 130, 165, 0.18);
  --color-border-bright: rgba(78, 139, 255, 0.4);

  /* Gradients */
  --gradient-hero: linear-gradient(135deg, #050B1A 0%, #0A1F4E 50%, #050B1A 100%);
  --gradient-blue: linear-gradient(135deg, #1E5BFF 0%, #00E0FF 100%);
  --gradient-card: linear-gradient(135deg, rgba(30, 91, 255, 0.08) 0%, rgba(0, 224, 255, 0.04) 100%);
  --gradient-text: linear-gradient(135deg, #FFFFFF 0%, #6FB6FF 100%);
  --gradient-glow: radial-gradient(circle at 50% 50%, rgba(30, 91, 255, 0.25) 0%, transparent 70%);

  /* Typography */
  --font-cn: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  --font-en: "Inter", "SF Pro Display", -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", Menlo, monospace;
  --font-base: var(--font-en), var(--font-cn);

  --fs-hero: clamp(2.4rem, 5.5vw, 5rem);
  --fs-h1: clamp(2rem, 3.6vw, 3.2rem);
  --fs-h2: clamp(1.6rem, 2.6vw, 2.4rem);
  --fs-h3: clamp(1.2rem, 1.8vw, 1.6rem);
  --fs-body: 1rem;
  --fs-sm: 0.875rem;
  --fs-xs: 0.75rem;

  /* Spacing */
  --container-max: 1320px;
  --section-pad-y: clamp(60px, 10vw, 140px);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 24px;
  --radius-pill: 999px;

  /* Effects */
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 10px 30px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 40px rgba(30, 91, 255, 0.35);
  --blur-card: blur(16px);

  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
  --transition-fast: 0.2s var(--ease-out);
  --transition-base: 0.4s var(--ease-out);
  --transition-slow: 0.8s var(--ease-out);

  /* Z-index */
  --z-bg: 0;
  --z-content: 1;
  --z-overlay: 50;
  --z-header: 100;
  --z-modal: 200;
}

/* =========================================
   Reset & Base
   ========================================= */

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-base);
  font-size: var(--fs-body);
  line-height: 1.6;
  color: var(--color-text-primary);
  background: var(--color-bg-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  position: relative;
  min-height: 100vh;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(30, 91, 255, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(30, 91, 255, 0.04) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: var(--z-bg);
  mask-image: radial-gradient(circle at 50% 0%, black 0%, transparent 80%);
  -webkit-mask-image: radial-gradient(circle at 50% 0%, black 0%, transparent 80%);
}

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

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
}

ul, ol {
  list-style: none;
}

::selection {
  background: var(--color-blue-primary);
  color: var(--color-white);
}

/* Custom scrollbar */
::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}
::-webkit-scrollbar-track {
  background: var(--color-bg-primary);
}
::-webkit-scrollbar-thumb {
  background: var(--color-gray-dark);
  border-radius: 5px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--color-blue-primary);
}

/* =========================================
   Layout Utilities
   ========================================= */

.container {
  width: min(100% - 48px, var(--container-max));
  margin-inline: auto;
}

.section {
  padding-block: var(--section-pad-y);
  position: relative;
}

.section-header {
  text-align: center;
  margin-bottom: clamp(40px, 6vw, 72px);
}

.section-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-blue-glow);
  margin-bottom: 16px;
}

.section-eyebrow::before {
  content: '';
  width: 32px;
  height: 1px;
  background: var(--color-blue-primary);
}

.section-title {
  font-size: var(--fs-h1);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 640px;
  margin-inline: auto;
}

/* =========================================
   Buttons
   ========================================= */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 0.95rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: all var(--transition-base);
  white-space: nowrap;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: var(--gradient-blue);
  color: var(--color-white);
  box-shadow: 0 8px 24px rgba(30, 91, 255, 0.35);
}

.btn-primary::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #4E8BFF 0%, #00E0FF 100%);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(30, 91, 255, 0.55);
}

.btn-primary:hover::before {
  opacity: 1;
}

.btn-primary span {
  position: relative;
  z-index: 1;
}

.btn-ghost {
  background: rgba(255, 255, 255, 0.04);
  color: var(--color-white);
  border: 1px solid var(--color-border);
  backdrop-filter: blur(10px);
}

.btn-ghost:hover {
  background: rgba(30, 91, 255, 0.12);
  border-color: var(--color-blue-bright);
  transform: translateY(-2px);
}

.btn-arrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--color-blue-glow);
  font-size: 0.95rem;
  font-weight: 500;
  transition: gap var(--transition-base);
}

.btn-arrow:hover {
  gap: 14px;
  color: var(--color-cyan);
}

.btn-arrow svg {
  width: 18px;
  height: 18px;
  transition: transform var(--transition-base);
}

.btn-arrow:hover svg {
  transform: translateX(4px);
}

/* =========================================
   Glass Card
   ========================================= */

.glass-card {
  background: var(--color-bg-card);
  backdrop-filter: var(--blur-card);
  -webkit-backdrop-filter: var(--blur-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
  transition: all var(--transition-base);
}

.glass-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-card);
  opacity: 0;
  transition: opacity var(--transition-base);
  pointer-events: none;
}

.glass-card:hover {
  border-color: var(--color-border-bright);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.glass-card:hover::before {
  opacity: 1;
}

/* =========================================
   Header / Navigation
   ========================================= */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-header);
  padding: 18px 0;
  transition: all var(--transition-base);
  backdrop-filter: blur(0);
}

.site-header.scrolled {
  padding: 12px 0;
  background: rgba(5, 11, 26, 0.85);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.nav-logo-mark {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--gradient-blue);
  display: grid;
  place-items: center;
  box-shadow: 0 0 24px rgba(30, 91, 255, 0.5);
  position: relative;
}

.nav-logo-mark::before {
  content: '';
  position: absolute;
  inset: -2px;
  border-radius: 12px;
  background: var(--gradient-blue);
  opacity: 0.3;
  filter: blur(8px);
  z-index: -1;
}

.nav-logo-mark svg {
  width: 22px;
  height: 22px;
  color: var(--color-white);
}

.nav-logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.nav-logo-name {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.nav-logo-tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.18em;
  color: var(--color-blue-glow);
  text-transform: uppercase;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 1;
  justify-content: center;
}

.nav-link {
  padding: 8px 14px;
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  border-radius: var(--radius-pill);
  position: relative;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-white);
  background: rgba(30, 91, 255, 0.1);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  padding: 4px;
  gap: 2px;
}

.lang-btn {
  padding: 6px 12px;
  font-size: 0.78rem;
  font-weight: 500;
  font-family: var(--font-mono);
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  letter-spacing: 0.05em;
  transition: all var(--transition-fast);
}

.lang-btn.active {
  background: var(--gradient-blue);
  color: var(--color-white);
}

.nav-cta {
  padding: 10px 22px;
  font-size: 0.85rem;
}

/* Mobile menu toggle */
.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--color-border);
  align-items: center;
  justify-content: center;
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--color-white);
  position: relative;
  transition: all var(--transition-fast);
}

.nav-toggle span::before,
.nav-toggle span::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--color-white);
  transition: all var(--transition-fast);
}

.nav-toggle span::before { top: -6px; }
.nav-toggle span::after { top: 6px; }

.nav-toggle.open span { background: transparent; }
.nav-toggle.open span::before { top: 0; transform: rotate(45deg); }
.nav-toggle.open span::after { top: 0; transform: rotate(-45deg); }

/* =========================================
   Footer
   ========================================= */

.site-footer {
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: 80px 0 32px;
  margin-top: 80px;
  position: relative;
  overflow: hidden;
}

.site-footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--color-blue-primary), transparent);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(3, 1fr);
  gap: 48px;
  margin-bottom: 48px;
}

.footer-brand {
  max-width: 360px;
}

.footer-brand-name {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.footer-brand-en {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-blue-glow);
  letter-spacing: 0.1em;
  margin-bottom: 16px;
}

.footer-tagline {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 20px;
}

.footer-social {
  display: flex;
  gap: 10px;
}

.footer-social a {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--color-border);
  display: grid;
  place-items: center;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.footer-social a:hover {
  background: rgba(30, 91, 255, 0.15);
  border-color: var(--color-blue-bright);
  color: var(--color-white);
  transform: translateY(-2px);
}

.footer-social svg {
  width: 18px;
  height: 18px;
}

.footer-col h4 {
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 18px;
  color: var(--color-white);
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-col a {
  color: var(--color-text-secondary);
  font-size: 0.88rem;
  transition: all var(--transition-fast);
}

.footer-col a:hover {
  color: var(--color-blue-glow);
  padding-left: 4px;
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  text-align: center;
}

.footer-bottom a {
  color: var(--color-text-muted);
}

.footer-bottom a:hover {
  color: var(--color-blue-glow);
}