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

:root {
  --primary: #1a5ce5;
  --primary-light: #4d83f1;
  --secondary: #22c5c0;
  --dark: #080f1a;
  --dark-mid: #111d33;
  --dark-light: #1c3054;
  --text-light: #e8edf5;
  --text-dim: #8ba3cc;
  --glow-blue: #6da8f0;
  --glow-cyan: #5dd8d4;
  --glass-bg: rgba(17, 29, 51, 0.6);
  --glass-border: rgba(109, 168, 240, 0.15);
  --glass-hover: rgba(109, 168, 240, 0.12);
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  background: var(--dark);
  color: var(--text-light);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.landing-page {
  position: relative;
  width: 100%;
  height: 100vh;
  overflow: hidden;
}

/* --- Background --- */
.bg-layer {
  position: absolute;
  inset: 0;
  z-index: 1;
  background: radial-gradient(ellipse at 50% 40%, #13203d 0%, #0a1225 45%, #050a14 100%);
}

.bg-layer::after {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 20% 80%, rgba(26, 92, 229, 0.06) 0%, transparent 50%),
    radial-gradient(ellipse at 75% 20%, rgba(34, 197, 192, 0.04) 0%, transparent 50%);
  pointer-events: none;
}

.grinding-svg {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: min(80vh, 80vw);
  height: min(80vh, 80vw);
  opacity: 0;
  animation: svgFadeIn 2s ease-out 0.2s forwards;
}

.bg-fallback {
  display: none;
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 50% 50%, #1a3050 0%, #0a1628 100%);
}

/* --- Content Layer --- */
.content-layer {
  position: relative;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  padding: 20px;
  text-align: center;
}

.logo-area {
  margin-bottom: 36px;
  opacity: 0;
  animation: fadeInUp 0.8s ease-out 0.4s forwards;
}

.logo-container {
  margin-bottom: 18px;
}

.logo {
  height: 56px;
  width: auto;
  filter: brightness(1.1) drop-shadow(0 0 24px rgba(109, 168, 240, 0.35));
  animation: logoGlow 4s ease-in-out infinite;
}

.company-name {
  font-size: clamp(1.3rem, 3.2vw, 2rem);
  font-weight: 700;
  letter-spacing: 0.06em;
  margin-bottom: 10px;
  background: linear-gradient(135deg, #e8edf5 0%, #a0c4f0 40%, #e8edf5 100%);
  background-size: 200% auto;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: shimmer 8s ease-in-out infinite;
}

.tagline {
  font-size: clamp(0.85rem, 1.8vw, 1.1rem);
  color: var(--text-dim);
  letter-spacing: 0.12em;
}

.tagline .zh-text,
.tagline .en-text {
  display: block;
}

.tagline .en-text {
  font-size: 0.85em;
  opacity: 0.6;
  margin-top: 3px;
  letter-spacing: 0.1em;
}

/* --- Language Selector --- */
.language-selector {
  display: flex;
  gap: 24px;
  margin: 28px 0;
  opacity: 0;
  animation: fadeInUp 0.8s ease-out 0.8s forwards;
}

.lang-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 24px 40px;
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  color: var(--text-light);
  text-decoration: none;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
  min-width: 160px;
}

.lang-btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 30%, var(--glass-hover) 100%);
  opacity: 0;
  transition: opacity 0.35s ease;
}

.lang-btn::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 20%;
  right: 20%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--glow-blue), transparent);
  opacity: 0;
  transition: opacity 0.35s ease;
}

.lang-btn:hover::before,
.lang-btn:hover::after {
  opacity: 1;
}

.lang-btn:hover {
  border-color: rgba(109, 168, 240, 0.4);
  transform: translateY(-4px);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.3), 0 0 60px rgba(26, 92, 229, 0.08);
}

.lang-btn:active {
  transform: translateY(-1px);
  transition: all 0.1s ease;
}

.lang-zh:hover {
  border-color: rgba(34, 197, 192, 0.4);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.3), 0 0 60px rgba(34, 197, 192, 0.08);
}

.lang-icon {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--glow-blue);
  transition: all 0.35s ease;
}

.lang-zh .lang-icon {
  color: var(--glow-cyan);
}

.lang-btn:hover .lang-icon {
  transform: scale(1.08);
}

.lang-label {
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: 0.06em;
}

.lang-sub {
  font-size: 0.75rem;
  color: var(--text-dim);
  opacity: 0.6;
  letter-spacing: 0.08em;
}

/* --- Tech Features --- */
.tech-info {
  display: flex;
  gap: 24px;
  opacity: 0;
  animation: fadeIn 1s ease-out 1.2s forwards;
}

.tech-item {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 0.75rem;
  color: var(--text-dim);
  opacity: 0.55;
  letter-spacing: 0.04em;
  padding: 6px 14px;
  border: 1px solid rgba(109, 168, 240, 0.08);
  border-radius: 20px;
  background: rgba(17, 29, 51, 0.3);
  transition: all 0.3s ease;
}

.tech-item:hover {
  opacity: 0.8;
  border-color: rgba(109, 168, 240, 0.2);
}

.tech-item svg {
  opacity: 0.5;
  flex-shrink: 0;
}

/* --- Corner Decorations --- */
.corner-decoration {
  position: absolute;
  width: 60px;
  height: 60px;
  z-index: 5;
  opacity: 0.08;
}

.corner-tl {
  top: 0; left: 0;
  border-top: 1px solid var(--glow-blue);
  border-left: 1px solid var(--glow-blue);
}

.corner-tr {
  top: 0; right: 0;
  border-top: 1px solid var(--glow-blue);
  border-right: 1px solid var(--glow-blue);
}

.corner-bl {
  bottom: 0; left: 0;
  border-bottom: 1px solid var(--glow-blue);
  border-left: 1px solid var(--glow-blue);
}

.corner-br {
  bottom: 0; right: 0;
  border-bottom: 1px solid var(--glow-blue);
  border-right: 1px solid var(--glow-blue);
}

/* --- Keyframes --- */
@keyframes svgFadeIn {
  from { opacity: 0; transform: translate(-50%, -50%) scale(0.85); }
  to { opacity: 1; transform: translate(-50%, -50%) scale(1); }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes shimmer {
  0%, 100% { background-position: 0% center; }
  50% { background-position: 200% center; }
}

@keyframes logoGlow {
  0%, 100% { filter: brightness(1.1) drop-shadow(0 0 24px rgba(109, 168, 240, 0.35)); }
  50% { filter: brightness(1.2) drop-shadow(0 0 36px rgba(109, 168, 240, 0.55)); }
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .language-selector {
    flex-direction: column;
    gap: 14px;
  }

  .lang-btn {
    padding: 18px 28px;
    flex-direction: row;
    gap: 12px;
    min-width: auto;
  }

  .lang-icon {
    width: 36px;
    height: 36px;
  }

  .logo {
    height: 42px;
  }

  .company-name {
    font-size: clamp(1rem, 4vw, 1.4rem);
  }

  .tagline {
    font-size: clamp(0.7rem, 2.5vw, 0.9rem);
  }

  .tech-info {
    flex-direction: column;
    gap: 8px;
    align-items: center;
  }

  .grinding-svg {
    width: min(90vh, 90vw);
    height: min(90vh, 90vw);
    opacity: 0.6;
  }

  .corner-decoration {
    width: 36px;
    height: 36px;
  }
}

@media (max-width: 480px) {
  .lang-btn {
    padding: 14px 22px;
  }

  .lang-label {
    font-size: 1rem;
  }

  .logo-area {
    margin-bottom: 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .grinding-svg {
    opacity: 1;
    transform: translate(-50%, -50%);
  }

  .language-selector,
  .tech-info,
  .logo-area {
    opacity: 1;
    animation: none;
  }
}