:root {
  --bg-primary: #050505;
  --bg-secondary: #0f0f0f;
  --bg-tertiary: #1a1a1a;
  --text-primary: #ffffff;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --accent: #10a37f;
  --accent-hover: #0d8c6d;
  --accent-glow: rgba(16, 163, 127, 0.3);
  --border: #27272a;
  --sidebar-width: 280px;
  --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  --container-max: 1200px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

h1, h2, h3, h4, .logo {
  font-family: 'Outfit', sans-serif;
}

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

.screen {
  min-height: 100vh;
  width: 100%;
}

.hidden {
  display: none !important;
}

/* Buttons */
.btn-primary {
  background: var(--accent);
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 10px 20px -10px var(--accent);
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: white;
  border: 1px solid var(--border);
  padding: 10px 20px;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-text {
  background: transparent;
  color: var(--text-secondary);
  border: none;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

.btn-text:hover {
  color: white;
}

.btn-lg {
  padding: 16px 32px;
  font-size: 18px;
}

/* Landing Nav */
.landing-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 20px 0;
  transition: var(--transition);
}

.landing-nav.scrolled {
  background: rgba(5, 5, 5, 0.8);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 12px 0;
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 24px;
  font-weight: 700;
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.nav-links a:hover {
  color: white;
}

.nav-actions {
  display: flex;
  gap: 16px;
  align-items: center;
}

/* Hero Section */
.hero {
  position: relative;
  padding: 180px 0 100px;
  overflow: hidden;
}

.hero-glow {
  position: absolute;
  top: -20%;
  left: 50%;
  transform: translateX(-50%);
  width: 80%;
  height: 60%;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  z-index: -1;
  filter: blur(80px);
}

.hero-container {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 60px;
  align-items: center;
}

.badge {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(16, 163, 127, 0.1);
  border: 1px solid var(--accent);
  color: var(--accent);
  border-radius: 100px;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 24px;
}

.hero h1 {
  font-size: 72px;
  line-height: 1.1;
  margin-bottom: 24px;
  font-weight: 800;
}

.text-gradient {
  background: linear-gradient(to right, #10a37f, #4ade80);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 20px;
  color: var(--text-secondary);
  margin-bottom: 40px;
  max-width: 600px;
}

.hero-btns {
  display: flex;
  gap: 16px;
  margin-bottom: 60px;
}

.hero-stats {
  display: flex;
  gap: 48px;
}

.stat-item {
  display: flex;
  flex-direction: column;
}

.stat-num {
  font-size: 32px;
  font-weight: 700;
  color: white;
}

.stat-label {
  font-size: 14px;
  color: var(--text-muted);
}

/* Chat Preview Card */
.chat-preview-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 40px 80px -20px rgba(0,0,0,0.5);
  transform: perspective(1000px) rotateY(-10deg) rotateX(5deg);
  transition: var(--transition);
}

.chat-preview-card:hover {
  transform: perspective(1000px) rotateY(0) rotateX(0);
}

.preview-header {
  padding: 12px 16px;
  background: var(--bg-tertiary);
  display: flex;
  gap: 6px;
}

.preview-header .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
}

.preview-body {
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.preview-msg {
  padding: 12px 16px;
  border-radius: 12px;
  font-size: 14px;
  max-width: 85%;
}

.preview-msg.user {
  background: var(--accent);
  align-self: flex-end;
}

.preview-msg.ai {
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
}

/* Features */
.features {
  padding: 100px 0;
  background: var(--bg-secondary);
}

.section-header {
  text-align: center;
  margin-bottom: 60px;
}

.section-header h2 {
  font-size: 48px;
  margin-bottom: 16px;
}

.section-header p {
  color: var(--text-secondary);
  font-size: 18px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 32px;
}

.feature-card {
  padding: 40px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: 20px;
  transition: var(--transition);
}

.feature-card:hover {
  border-color: var(--accent);
  transform: translateY(-10px);
}

.feature-icon {
  font-size: 40px;
  margin-bottom: 24px;
}

.feature-card h3 {
  font-size: 24px;
  margin-bottom: 16px;
}

.feature-card p {
  color: var(--text-secondary);
}

/* CTA Banner */
.cta-banner {
  padding: 100px 0;
  text-align: center;
  background: linear-gradient(to bottom, var(--bg-secondary), var(--bg-primary));
}

.cta-content h2 {
  font-size: 48px;
  margin-bottom: 24px;
}

.cta-content p {
  font-size: 20px;
  color: var(--text-secondary);
  margin-bottom: 40px;
}

/* Footer */
.landing-footer {
  padding: 80px 0 40px;
  border-top: 1px solid var(--border);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 60px;
}

.footer-brand p {
  margin-top: 16px;
  color: var(--text-secondary);
  max-width: 240px;
}

.footer-links h4 {
  margin-bottom: 24px;
  font-size: 18px;
}

.footer-links a {
  display: block;
  color: var(--text-muted);
  text-decoration: none;
  margin-bottom: 12px;
  transition: var(--transition);
}

.footer-links a:hover {
  color: var(--accent);
}

.footer-bottom {
  padding-top: 40px;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-muted);
  font-size: 14px;
}

/* Auth Screen Overrides */
#auth-screen {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.auth-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.8);
  backdrop-filter: blur(8px);
}

.auth-container {
  position: relative;
  width: 100%;
  max-width: 440px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 48px;
  z-index: 1;
  animation: slideUp 0.5s ease;
}

.auth-close {
  position: absolute;
  top: 24px;
  right: 24px;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 32px;
  cursor: pointer;
}

.auth-logo {
  text-align: center;
  margin-bottom: 40px;
}

.auth-logo h1 {
  font-size: 32px;
  margin-top: 16px;
}

.auth-logo p {
  color: var(--text-secondary);
}

.input-group {
  margin-bottom: 20px;
}

.input-group label {
  display: block;
  margin-bottom: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
}

.input-group input {
  width: 100%;
  padding: 14px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: 12px;
  color: white;
  font-size: 16px;
  transition: var(--transition);
}

.input-group input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-glow);
}

.submit-btn {
  width: 100%;
  padding: 16px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 12px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  margin-top: 12px;
}

.cancel-btn {
  width: 100%;
  background: transparent;
  border: none;
  color: var(--text-muted);
  margin-top: 16px;
  cursor: pointer;
}

/* Chat Screen Overrides */
#chat-screen {
  background: var(--bg-primary);
  display: flex;
}

.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
}

.chat-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  position: relative;
}

.messages-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 40px 20px 150px;
}

.message {
  padding: 32px 0;
  border-bottom: 1px solid rgba(255,255,255,0.05);
}

.message.assistant {
  background: rgba(255,255,255,0.02);
  margin: 0 -20px;
  padding: 32px 20px;
}

/* Animations */
@keyframes slideUp {
  from { opacity: 0; transform: translateY(40px); }
  to { opacity: 1; transform: translateY(0); }
}

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

/* Mobile */
@media (max-width: 1024px) {
  .hero-container {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .hero h1 { font-size: 56px; }
  .hero-btns, .hero-stats { justify-content: center; }
  .hero-visual { display: none; }
  .nav-links { display: none; }
}

@media (max-width: 768px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .hero h1 { font-size: 40px; }
}