/* === Variables === */
:root {
  --bg: #fafafa;
  --bg-alt: #f0f0f0;
  --text: #1a1a2e;
  --text-secondary: #555;
  --accent: #6366f1;
  --accent-light: #818cf8;
  --accent-bg: rgba(99, 102, 241, 0.08);
  --card-bg: #ffffff;
  --card-border: #e5e7eb;
  --card-shadow: 0 1px 3px rgba(0,0,0,0.06);
  --nav-bg: rgba(250, 250, 250, 0.85);
  --code-bg: #f1f5f9;
  --radius: 12px;
  --transition: 0.3s ease;
}

[data-theme="dark"] {
  --bg: #0f172a;
  --bg-alt: #1e293b;
  --text: #e2e8f0;
  --text-secondary: #94a3b8;
  --accent: #818cf8;
  --accent-light: #a5b4fc;
  --accent-bg: rgba(129, 140, 248, 0.1);
  --card-bg: #1e293b;
  --card-border: #334155;
  --card-shadow: 0 1px 3px rgba(0,0,0,0.3);
  --nav-bg: rgba(15, 23, 42, 0.85);
  --code-bg: #1e293b;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: 'Inter', 'Noto Sans SC', -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  transition: background var(--transition), color var(--transition);
}

a { color: var(--accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent-light); }

.container { max-width: 1100px; margin: 0 auto; padding: 0 24px; }

/* === Nav === */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--card-border);
  transition: background var(--transition), border var(--transition);
}

.nav-inner {
  max-width: 1100px; margin: 0 auto; padding: 0 24px;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-size: 1.25rem; font-weight: 700;
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-links { display: flex; align-items: center; gap: 28px; }
.nav-links a { color: var(--text-secondary); font-size: 0.9rem; font-weight: 500; }
.nav-links a:hover { color: var(--accent); }

.theme-toggle {
  background: none; border: none; color: var(--text-secondary);
  cursor: pointer; font-size: 1.1rem; padding: 6px;
  transition: color var(--transition);
}
.theme-toggle:hover { color: var(--accent); }

.lang-toggle {
  background: none; border: 1px solid var(--card-border); color: var(--text-secondary);
  cursor: pointer; font-size: 0.82rem; padding: 4px 10px;
  border-radius: 6px; font-weight: 500; font-family: inherit;
  transition: all var(--transition); white-space: nowrap;
}
.lang-toggle:hover { color: var(--accent); border-color: var(--accent); }

.mobile-controls {
  display: none; align-items: center; gap: 8px;
}

.mobile-menu-btn {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 6px;
}
.mobile-menu-btn span {
  display: block; width: 22px; height: 2px;
  background: var(--text-secondary); transition: var(--transition);
}

.mobile-menu {
  display: none; position: fixed; top: 64px; left: 0; right: 0;
  background: var(--card-bg); border-bottom: 1px solid var(--card-border);
  padding: 16px 24px; z-index: 99;
  flex-direction: column; gap: 16px;
}
.mobile-menu a { color: var(--text); font-weight: 500; font-size: 1rem; }

@media (max-width: 768px) {
  .nav-links { display: none; }
  .mobile-controls { display: flex; }
  .mobile-menu-btn { display: flex; }
  .mobile-menu.active { display: flex; }
}

/* === Hero === */
.hero {
  min-height: 100vh; display: flex; flex-direction: column;
  justify-content: center; align-items: center;
  padding: 100px 24px 60px;
}

.hero-content {
  max-width: 1100px; width: 100%;
  display: flex; align-items: center; gap: 60px;
}

.hero-text { flex: 1; }

.hero-greeting {
  font-size: 1.1rem; color: var(--accent);
  font-weight: 500; margin-bottom: 8px;
}

.hero-name {
  font-size: 3.2rem; font-weight: 700;
  line-height: 1.2; margin-bottom: 8px;
}

.hero-name-cn {
  font-size: 1.8rem; color: var(--text-secondary);
  font-weight: 400; display: inline-block; margin-left: 8px;
}

.hero-title {
  font-size: 1.3rem; color: var(--accent);
  font-weight: 500; margin-bottom: 20px;
}

.hero-desc {
  color: var(--text-secondary); font-size: 1.05rem;
  max-width: 540px; margin-bottom: 28px; line-height: 1.8;
}

.hero-links { display: flex; gap: 12px; flex-wrap: wrap; }

.hero-btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 20px; border-radius: 8px;
  font-weight: 500; font-size: 0.9rem;
  border: 1px solid var(--card-border);
  color: var(--text); background: var(--card-bg);
  transition: all var(--transition);
}
.hero-btn:hover {
  border-color: var(--accent); color: var(--accent);
  transform: translateY(-2px); box-shadow: 0 4px 12px rgba(99,102,241,0.15);
}
.hero-btn-primary {
  background: var(--accent); color: #fff; border-color: var(--accent);
}
.hero-btn-primary:hover { background: var(--accent-light); color: #fff; }

.hero-visual { flex-shrink: 0; }

.hero-avatar {
  width: 260px; height: 260px; border-radius: 50%;
  overflow: hidden; position: relative;
  border: 3px solid var(--accent);
  box-shadow: 0 0 0 8px var(--accent-bg);
}
.hero-avatar img {
  width: 100%; height: 100%; object-fit: cover;
  object-position: center 20%;
}
.hero-avatar.no-img {
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
}
.avatar-fallback {
  font-size: 4rem; font-weight: 700; color: #fff;
  display: none;
}
.hero-avatar.no-img .avatar-fallback { display: block; }

.scroll-hint {
  margin-top: 40px; animation: bounce 2s infinite;
  color: var(--text-secondary); font-size: 1.2rem;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(8px); }
}

@media (max-width: 768px) {
  .hero-content { flex-direction: column-reverse; gap: 40px; text-align: center; }
  .hero-name { font-size: 2.2rem; }
  .hero-name-cn { display: block; margin: 4px 0 0; }
  .hero-links { justify-content: center; }
  .hero-avatar { width: 180px; height: 180px; }
  .hero-desc { margin-left: auto; margin-right: auto; }
}

/* === Sections === */
.section { padding: 80px 0; }
.section-alt { background: var(--bg-alt); }

.section-title {
  font-size: 2rem; font-weight: 700;
  margin-bottom: 48px; text-align: center;
  position: relative;
}
.section-title::after {
  content: ''; display: block; width: 40px; height: 3px;
  background: var(--accent); margin: 12px auto 0; border-radius: 2px;
}

/* === About === */
.about-grid {
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.about-card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 28px;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}
.about-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
}
.about-card > i {
  font-size: 1.5rem; color: var(--accent); margin-bottom: 16px;
}
.about-card h3 { font-size: 1.15rem; margin-bottom: 12px; }
.about-card p { color: var(--text-secondary); font-size: 0.92rem; margin-bottom: 10px; }
.about-card .subtle { font-size: 0.82rem; opacity: 0.7; }

.skills-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.skills-tags span {
  padding: 5px 12px; border-radius: 20px; font-size: 0.82rem;
  background: var(--accent-bg); color: var(--accent); font-weight: 500;
}

@media (max-width: 768px) {
  .about-grid { grid-template-columns: 1fr; }
}

/* === Timeline === */
.timeline { position: relative; max-width: 700px; margin: 0 auto; }
.timeline::before {
  content: ''; position: absolute; left: 0; top: 0; bottom: 0;
  width: 2px; background: var(--card-border);
}

.timeline-item {
  position: relative; padding-left: 36px; margin-bottom: 40px;
}
.timeline-item:last-child { margin-bottom: 0; }

.timeline-dot {
  position: absolute; left: -5px; top: 6px;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--accent); border: 2px solid var(--bg);
  box-shadow: 0 0 0 3px var(--accent-bg);
}

.timeline-date {
  font-size: 0.82rem; color: var(--accent);
  font-weight: 600; margin-bottom: 6px;
}

.timeline-content {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 24px;
  box-shadow: var(--card-shadow);
}
.timeline-content h3 { font-size: 1.1rem; margin-bottom: 4px; }
.timeline-company { color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 12px; }
.timeline-content ul { padding-left: 18px; }
.timeline-content li {
  color: var(--text-secondary); font-size: 0.88rem;
  margin-bottom: 6px; line-height: 1.6;
}

/* === Projects === */
.projects-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 28px;
  box-shadow: var(--card-shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex; flex-direction: column;
}
.project-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
}
.project-card.featured { border-color: var(--accent); }
.project-card.featured::before {
  content: 'Featured'; display: inline-block;
  font-size: 0.72rem; font-weight: 600; color: var(--accent);
  background: var(--accent-bg); padding: 3px 10px;
  border-radius: 20px; margin-bottom: 12px; width: fit-content;
}

.project-icon {
  font-size: 1.8rem; color: var(--accent); margin-bottom: 16px;
}
.project-card h3 { font-size: 1.1rem; margin-bottom: 10px; }
.project-card p { color: var(--text-secondary); font-size: 0.88rem; flex: 1; margin-bottom: 16px; }

.project-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 16px; }
.project-tags span {
  padding: 3px 10px; border-radius: 20px; font-size: 0.75rem;
  background: var(--accent-bg); color: var(--accent); font-weight: 500;
}

.project-links { display: flex; gap: 16px; flex-wrap: wrap; }

.project-link {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 0.88rem; font-weight: 500;
}

/* === Contact === */
.contact-desc {
  text-align: center; color: var(--text-secondary);
  max-width: 500px; margin: -20px auto 36px;
}

.contact-links {
  display: flex; flex-direction: column; align-items: center; gap: 16px;
}

.contact-item {
  display: flex; align-items: center; gap: 12px;
  padding: 14px 28px; border-radius: var(--radius);
  background: var(--card-bg); border: 1px solid var(--card-border);
  color: var(--text); font-size: 0.95rem;
  transition: all var(--transition); min-width: 340px; justify-content: center;
}
.contact-item:hover {
  border-color: var(--accent); color: var(--accent);
  transform: translateY(-2px);
}
.contact-item i { font-size: 1.2rem; color: var(--accent); }

/* === Footer === */
.footer {
  text-align: center; padding: 24px;
  color: var(--text-secondary); font-size: 0.82rem;
  border-top: 1px solid var(--card-border);
}

/* === Chat Widget === */
.chat-widget { position: fixed; bottom: 24px; right: 24px; z-index: 200; }

.chat-toggle {
  width: 56px; height: 56px; border-radius: 50%;
  background: var(--accent); color: #fff; border: none;
  font-size: 1.4rem; cursor: pointer;
  box-shadow: 0 4px 16px rgba(99,102,241,0.4);
  transition: all var(--transition);
  position: relative;
}
.chat-toggle:hover { transform: scale(1.08); }

.chat-badge {
  position: absolute; bottom: calc(100% + 8px); right: 0;
  white-space: nowrap; font-size: 0.78rem; font-weight: 500;
  background: var(--card-bg); color: var(--text);
  padding: 6px 14px; border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.12);
  opacity: 1; transition: opacity var(--transition);
  pointer-events: none;
}
.chat-badge::after {
  content: ''; position: absolute; top: 100%; right: 20px;
  border: 6px solid transparent; border-top-color: var(--card-bg);
}

.chat-panel {
  position: absolute; bottom: 70px; right: 0;
  width: 380px; max-height: 520px;
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: 16px; box-shadow: 0 8px 32px rgba(0,0,0,0.15);
  display: none; flex-direction: column;
  overflow: hidden;
}
.chat-panel.active { display: flex; }

.chat-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px; border-bottom: 1px solid var(--card-border);
  background: var(--accent); color: #fff;
}
.chat-header-info { display: flex; align-items: center; gap: 12px; }
.chat-header-info p { font-size: 0.78rem; opacity: 0.85; margin: 0; color: rgba(255,255,255,0.85); }
.chat-header-info strong { color: #fff; }

.chat-avatar {
  width: 36px; height: 36px; border-radius: 50%;
  background: rgba(255,255,255,0.2); display: flex;
  align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.85rem;
}

.chat-close {
  background: none; border: none; color: rgba(255,255,255,0.8);
  cursor: pointer; font-size: 1.1rem; padding: 4px;
}
.chat-close:hover { color: #fff; }

.chat-messages {
  flex: 1; overflow-y: auto; padding: 16px;
  display: flex; flex-direction: column; gap: 12px;
  max-height: 360px; min-height: 200px;
}

.chat-message {
  max-width: 85%; padding: 10px 14px; border-radius: 12px;
  font-size: 0.88rem; line-height: 1.6;
}
.chat-message.bot {
  background: var(--accent-bg); color: var(--text);
  align-self: flex-start; border-bottom-left-radius: 4px;
}
.chat-message.user {
  background: var(--accent); color: #fff;
  align-self: flex-end; border-bottom-right-radius: 4px;
}
.chat-message p { margin: 0; }

.chat-message.bot.typing::after {
  content: ''; display: inline-block;
  width: 4px; height: 4px; border-radius: 50%;
  background: var(--accent); margin-left: 4px;
  animation: typingDot 1s infinite;
}
@keyframes typingDot {
  0%, 100% { opacity: 0.3; }
  50% { opacity: 1; }
}

.chat-mode-tabs {
  display: flex; padding: 6px 12px 0; gap: 4px;
  border-top: 1px solid var(--card-border);
}
.chat-mode-tab {
  flex: 1; padding: 6px 0; border: none; background: none;
  font-size: 0.78rem; font-weight: 500; font-family: inherit;
  color: var(--text-secondary); cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all var(--transition);
}
.chat-mode-tab:hover { color: var(--accent); }
.chat-mode-tab.active {
  color: var(--accent); border-bottom-color: var(--accent);
}

.chat-input-wrap {
  display: flex; padding: 12px; gap: 8px;
}
.chat-input-wrap input {
  flex: 1; padding: 10px 14px; border-radius: 8px;
  border: 1px solid var(--card-border); background: var(--bg);
  color: var(--text); font-size: 0.88rem; outline: none;
  font-family: inherit;
  transition: border var(--transition);
}
.chat-input-wrap input:focus { border-color: var(--accent); }
.chat-input-wrap button {
  width: 40px; height: 40px; border-radius: 8px;
  background: var(--accent); color: #fff; border: none;
  cursor: pointer; font-size: 0.9rem;
  transition: background var(--transition);
}
.chat-input-wrap button:hover { background: var(--accent-light); }
.chat-input-wrap button:disabled { opacity: 0.5; cursor: not-allowed; }

@media (max-width: 480px) {
  .chat-panel { width: calc(100vw - 32px); right: -8px; }
  .chat-badge { display: none; }
}

/* === Animations === */
.fade-in {
  opacity: 0; transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible { opacity: 1; transform: translateY(0); }