:root {
  --bg-color: #ffffff; /* 纯白背景 */
  --text-main: #1d1d1f; /* 深色主文本 */
  --text-muted: #86868b; /* 灰色副文本 */
  --accent: #15192a; /* 产品商标主色调，深邃科技蓝黑 */
  --accent-glow: rgba(21, 25, 42, 0.3);
  --font-mono: 'Space Mono', monospace, 'Courier New', Courier;
  /* 引入 ZCOOL KuaiLe 为中文提供活泼艺术感，英文使用 Fredoka */
  --font-lively: 'ZCOOL KuaiLe', 'Fredoka', 'Quicksand', 'Arial', sans-serif; 
  
  --nav-height: 80px;
}

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

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  font-family: var(--font-mono);
  overflow-x: hidden;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ================== Navbar ================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--nav-height);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 4vw;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
  transition: all 0.3s ease;
}

.nav-logo {
  display: flex;
  align-items: center;
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -1px;
}

.logo-img {
  height: 36px;
  width: auto;
  margin-right: 12px;
  border-radius: 8px; /* 适应可能带背景的图片 */
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.nav-links {
  display: flex;
  gap: 2rem;
  align-items: center;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-family: var(--font-lively);
  font-weight: 500;
  transition: color 0.3s ease;
}

.nav-links a:hover {
  color: var(--text-main);
}

.lang-btn {
  background: transparent;
  border: 1px solid var(--text-muted);
  color: var(--text-muted);
  padding: 0.3rem 0.8rem;
  font-family: var(--font-lively);
  font-size: 0.8rem;
  cursor: pointer;
  border-radius: 6px;
  transition: all 0.3s ease;
}

.lang-btn:hover {
  color: var(--accent);
  border-color: var(--accent);
  box-shadow: 0 0 8px var(--accent-glow);
}

/* ================== Scroll Container ================== */
.scroll-container {
  height: 100vh;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
  scroll-behavior: smooth;
}

.scroll-container::-webkit-scrollbar {
  width: 8px;
}
.scroll-container::-webkit-scrollbar-track {
  background: var(--bg-color);
}
.scroll-container::-webkit-scrollbar-thumb {
  background: #d1d1d6;
  border-radius: 10px;
}

/* ================== Sections ================== */
.fs-section {
  height: 100vh;
  width: 100vw;
  scroll-snap-align: start;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding: 0 5vw;
}

.content {
  max-width: 1100px;
  width: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  z-index: 10;
}

/* Animations Trigger */
.fade-element {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 1s cubic-bezier(0.16, 1, 0.3, 1), transform 1s cubic-bezier(0.16, 1, 0.3, 1);
}

.fade-element.in-view {
  opacity: 1;
  transform: translateY(0);
}

/* ================== Typography ================== */
.hero-logo {
  height: 100px;
  width: auto;
  margin-bottom: 1.5rem;
  border-radius: 20px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

.huge-title {
  font-size: clamp(3rem, 6vw, 6.5rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.04em;
  margin-bottom: 2rem;
  max-width: 900px;
  color: #000;
}

.huge-title::selection {
  background: var(--accent);
  color: #fff;
}

.subtitle {
  font-family: var(--font-lively);
  font-size: clamp(1.1rem, 1.6vw, 1.4rem);
  font-weight: 500;
  color: var(--text-muted);
  max-width: 700px;
  margin-bottom: 3rem;
  line-height: 1.6;
}

.btn {
  display: inline-block;
  padding: 1rem 2.5rem;
  font-size: 1.1rem;
  font-weight: 600;
  font-family: var(--font-lively);
  text-decoration: none;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  letter-spacing: 0.02em;
}

.primary-btn {
  background: var(--accent);
  color: #fff;
  border: none;
  box-shadow: 0 8px 20px var(--accent-glow);
}

.primary-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 25px var(--accent-glow);
  background: #2a314f;
}

.secondary-btn {
  background: rgba(21, 25, 42, 0.18);
  color: var(--accent);
  border: 2px solid transparent;
}

.secondary-btn:hover {
  transform: translateY(-2px);
  background: rgba(21, 25, 42, 0.28);
}

.outline-btn {
  background: transparent;
  color: var(--text-main);
  border: 2px solid rgba(0, 0, 0, 0.15);
}

.outline-btn:hover {
  border-color: var(--text-main);
  background: rgba(0, 0, 0, 0.03);
}

.btn-group {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

/* ================== Dropdown ================== */
.dropdown-wrapper {
  position: relative;
  display: inline-block;
}

.dropdown-trigger {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.dropdown-arrow {
  margin-left: 8px;
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.dropdown-wrapper:hover .dropdown-arrow,
.dropdown-wrapper:focus-within .dropdown-arrow,
.dropdown-wrapper.is-open .dropdown-arrow {
  transform: rotate(-180deg);
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(15px);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  background: #ffffff;
  min-width: 220px;
  border-radius: 16px;
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.08); /* 极简阴影 */
  padding: 0.5rem;
  margin-top: 0.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  z-index: 100;
  border: 1px solid rgba(0, 0, 0, 0.04);
}

.dropdown-wrapper:hover .dropdown-menu,
.dropdown-wrapper:focus-within .dropdown-menu,
.dropdown-wrapper.is-open .dropdown-menu {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateX(-50%) translateY(0); /* Fade-in & Slide-up 组合 */
}

.dropdown-item {
  text-decoration: none;
  color: var(--text-main);
  padding: 0.8rem 1.2rem;
  border-radius: 10px;
  font-family: var(--font-lively);
  font-size: 0.95rem;
  font-weight: 500;
  transition: background-color 0.2s ease, color 0.2s ease;
  white-space: nowrap;
  text-align: center;
}

.dropdown-item:hover {
  background-color: #f5f5f7; /* 平滑的灰白色过渡 */
  color: #000;
}

/* ================== Features ================== */
.feature-section .content {
  align-items: center;
  text-align: center;
}

.feature-section h2 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  margin-bottom: 1.5rem;
  font-weight: 700;
  letter-spacing: -2px;
  color: #000;
}

.feature-section p {
  font-family: var(--font-lively);
  font-weight: 500;
  font-size: clamp(1.1rem, 1.4vw, 1.3rem);
  color: var(--text-muted);
  max-width: 650px;
}

/* ================== Abstract Graphics ================== */
.abstract-graphic {
  width: 200px;
  height: 200px;
  margin-bottom: 3rem;
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Graphic 1: Gear & Extension */
.gear-spinner {
  width: 120px;
  height: 120px;
  border: 3px dashed rgba(0, 0, 0, 0.15);
  border-radius: 50%;
  position: absolute;
  animation: spin 15s linear infinite;
}

.extension-icon {
  width: 45px;
  height: 45px;
  background: var(--accent);
  box-shadow: 0 10px 20px var(--accent-glow);
  clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 50% 100%, 0% 75%, 0% 25%);
  animation: float 4s ease-in-out infinite;
}

/* Graphic 2: AI Brain */
.ai-brain .nodes span {
  position: absolute;
  width: 10px;
  height: 10px;
  background: #000;
  border-radius: 50%;
  box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
}
.ai-brain .nodes span:nth-child(1) { top: 30%; left: 30%; animation: pulse 2s infinite; }
.ai-brain .nodes span:nth-child(2) { top: 60%; left: 70%; animation: pulse 2s infinite 0.5s; }
.ai-brain .nodes span:nth-child(3) { top: 20%; left: 60%; animation: pulse 2s infinite 1s; }

.ai-brain .code-lines {
  display: flex;
  flex-direction: column;
  gap: 12px;
  width: 100px;
}
.ai-brain .line {
  height: 3px;
  background: var(--accent);
  width: 100%;
  border-radius: 2px;
  box-shadow: 0 4px 10px var(--accent-glow);
}
.ai-brain .line.short {
  width: 60%;
}

/* Graphic 3: Timeline Match */
.timeline-match .frame {
  width: 55px;
  height: 35px;
  border: 2px solid rgba(0, 0, 0, 0.15);
  border-radius: 4px;
  position: absolute;
  left: 20%;
}
.timeline-match .frame.active {
  left: 60%;
  border-color: var(--accent);
  box-shadow: 0 8px 20px var(--accent-glow);
}
.timeline-match .connection-line {
  position: absolute;
  width: 80px;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  animation: scan 2s linear infinite;
}

/* Graphic 4: Export */
.export-icon .scissors {
  width: 60px;
  height: 3px;
  background: rgba(0, 0, 0, 0.3);
  position: absolute;
  transform: rotate(-15deg);
  border-radius: 2px;
}
.export-icon .arrow-up {
  width: 0;
  height: 0;
  border-left: 18px solid transparent;
  border-right: 18px solid transparent;
  border-bottom: 28px solid var(--accent);
  position: absolute;
  margin-top: -30px;
  filter: drop-shadow(0 8px 15px var(--accent-glow));
  animation: slideUpIcon 2s ease-in-out infinite;
}

/* Keyframes */
@keyframes spin { 100% { transform: rotate(360deg); } }
@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-15px); }
}
@keyframes pulse {
  0%, 100% { transform: scale(1); opacity: 0.6; }
  50% { transform: scale(1.5); opacity: 1; background: var(--accent); box-shadow: 0 4px 15px var(--accent-glow); }
}
@keyframes scan {
  0% { transform: translateX(-40px); opacity: 0; }
  50% { opacity: 1; }
  100% { transform: translateX(40px); opacity: 0; }
}
@keyframes slideUpIcon {
  0% { transform: translateY(10px); opacity: 0; }
  50% { opacity: 1; }
  100% { transform: translateY(-20px); opacity: 0; }
}

/* ================== Footer & Layout Specifics ================== */
.download-section {
  justify-content: center;
  position: relative;
}

.download-section .content {
  align-items: center;
  text-align: center;
}

.bg-shape {
  position: absolute;
  width: 70vw;
  height: 70vw;
  background: radial-gradient(circle, rgba(21, 25, 42, 0.04) 0%, rgba(255, 255, 255, 0) 70%);
  border-radius: 50%;
  top: -20vh;
  right: -20vw;
  pointer-events: none;
  z-index: 1;
}

.footer {
  position: absolute;
  bottom: 2rem;
  width: 100%;
  text-align: center;
  font-size: 0.85rem;
  font-family: var(--font-lively);
  color: var(--text-muted);
}

/* ================== Modal ================== */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  z-index: 2000;
  display: flex;
  justify-content: center;
  align-items: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.4s ease, visibility 0.4s ease;
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: #0d111a;
  color: #fff;
  width: 90%;
  max-width: 540px;
  border-radius: 24px;
  padding: 3rem;
  position: relative;
  transform: translateY(30px) scale(0.98);
  opacity: 0;
  transition: all 0.5s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.4), inset 0 1px 0 rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.modal-overlay.active .modal-content {
  transform: translateY(0) scale(1);
  opacity: 1;
}

.modal-close {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  background: transparent;
  border: none;
  color: rgba(255, 255, 255, 0.5);
  font-size: 2rem;
  cursor: pointer;
  line-height: 1;
  transition: color 0.3s ease, transform 0.3s ease;
}

.modal-close:hover {
  color: #fff;
  transform: rotate(90deg);
}

.modal-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 1.2rem;
  letter-spacing: -1px;
}

.modal-desc {
  font-family: var(--font-lively);
  font-size: 1.05rem;
  color: rgba(255, 255, 255, 0.7);
  line-height: 1.6;
  margin-bottom: 2.5rem;
}

.contact-methods {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
  margin-bottom: 3rem;
  padding: 1.5rem;
  background: rgba(255, 255, 255, 0.03);
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.contact-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1.1rem;
}

.contact-label {
  color: rgba(255, 255, 255, 0.5);
  font-family: var(--font-lively);
}

.contact-value {
  font-family: var(--font-mono);
  font-weight: 700;
  color: #fff;
  letter-spacing: 0.5px;
  user-select: all;
}

.social-matrix {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.social-link {
  display: flex;
  align-items: center;
  text-decoration: none;
  padding: 1rem 1.2rem;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.04);
  transition: all 0.3s ease;
}

.social-link:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.1);
  transform: translateX(5px);
}

.social-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.3rem 0.6rem;
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
  border-radius: 6px;
  margin-right: 1.2rem;
  letter-spacing: 1px;
}

.social-text {
  font-family: var(--font-lively);
  color: rgba(255, 255, 255, 0.85);
  font-size: 1.05rem;
  font-weight: 500;
  transition: color 0.3s ease;
}

.social-link:hover .social-text {
  color: #fff;
}

/* Responsive */
@media (max-width: 768px) {
  .nav-links a { display: none; }
  .nav-links { gap: 1rem; }
  .btn { padding: 0.8rem 2rem; font-size: 1rem; }
  .modal-content {
    padding: 2rem;
    width: 92%;
  }
}