:root {
  --primary: #3B82F6;
  --secondary: #8B5CF6;
  --accent: #FACC15;
  --bg-color: #F9FAFB;
  --text-primary: #111827;
  --text-secondary: #4B5563;
  --card-bg: #FFFFFF;
  --border-radius: 20px;
  --shadow-soft: 0 10px 40px rgba(0, 0, 0, 0.05);
  --shadow-hover: 0 20px 40px rgba(59, 130, 246, 0.2);
  --gradient-btn: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
}

[data-theme="dark"] {
  --bg-color: #0F172A;
  --text-primary: #F8FAFC;
  --text-secondary: #94A3B8;
  --card-bg: #1E293B;
  --shadow-soft: 0 10px 40px rgba(0, 0, 0, 0.3);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  transition: background-color 0.3s, color 0.3s;
}

/* Typography */
h1, h2, h3 {
  line-height: 1.2;
  font-weight: 800;
  letter-spacing: -0.02em;
}

/* Background Shapes */
.bg-shape {
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
  z-index: -1;
  opacity: 0.4;
  animation: float 10s infinite alternate ease-in-out;
}

.shape-1 {
  width: 500px;
  height: 500px;
  background: var(--primary);
  top: -100px;
  left: -200px;
}

.shape-2 {
  width: 400px;
  height: 400px;
  background: var(--secondary);
  bottom: 20%;
  right: -100px;
  animation-duration: 12s;
}

@keyframes float {
  0% { transform: translateY(0) scale(1); }
  100% { transform: translateY(-30px) scale(1.05); }
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Navbar */
nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 24px 0;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  display: flex;
  align-items: center;
  gap: 8px;
}

.logo i {
  color: var(--accent);
  font-size: 2rem;
}

.theme-toggle {
  background: var(--card-bg);
  border: none;
  border-radius: 50%;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow-soft);
  color: var(--text-primary);
  font-size: 1.25rem;
  transition: transform 0.2s, box-shadow 0.2s;
}

.theme-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

/* Hero Section */
.hero {
  padding: 80px 0;
  text-align: center;
  position: relative;
}

.hero h1 {
  font-size: clamp(3rem, 8vw, 5rem);
  margin-bottom: 24px;
  background: var(--gradient-btn);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 48px;
}

/* Chat Input Component */
.chat-input-wrapper {
  max-width: 700px;
  margin: 0 auto 48px;
  position: relative;
  transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.chat-input-wrapper:focus-within {
  transform: scale(1.02);
}

.chat-input-box {
  background: var(--card-bg);
  border-radius: 30px;
  padding: 8px 8px 8px 24px;
  display: flex;
  align-items: center;
  box-shadow: var(--shadow-soft);
  border: 2px solid transparent;
  transition: border-color 0.3s, box-shadow 0.3s;
}

.chat-input-wrapper:focus-within .chat-input-box {
  border-color: var(--primary);
  box-shadow: var(--shadow-hover);
}

.chat-input-box input {
  flex: 1;
  border: none;
  background: transparent;
  font-size: 1.125rem;
  color: var(--text-primary);
  outline: none;
  font-family: inherit;
}

.chat-input-box input::placeholder {
  color: #9CA3AF;
}

.btn-send-hero {
  background: var(--gradient-btn);
  color: white;
  border: none;
  border-radius: 24px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1.25rem;
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn-send-hero:hover {
  transform: scale(1.05);
  box-shadow: 0 0 15px rgba(139, 92, 246, 0.5);
}

.btn-send-hero:active {
  transform: scale(0.95);
}

/* CTA Buttons */
.hero-ctas {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  padding: 16px 32px;
  border-radius: 30px;
  font-weight: 700;
  font-size: 1.125rem;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  border: none;
}

.btn-primary {
  background: var(--gradient-btn);
  color: white;
  box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
}

.btn-secondary {
  background: var(--card-bg);
  color: var(--text-primary);
  box-shadow: var(--shadow-soft);
}

.btn-secondary:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
}

/* Section 2: How It Works */
.how-it-works {
  padding: 80px 0;
}

.section-title {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 48px;
}

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

.step-card {
  background: var(--card-bg);
  padding: 40px 24px;
  border-radius: var(--border-radius);
  text-align: center;
  box-shadow: var(--shadow-soft);
  position: relative;
  transition: transform 0.3s, box-shadow 0.3s;
}

.step-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-hover);
}

.step-number {
  position: absolute;
  top: -20px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--accent);
  color: #111827;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.25rem;
  border: 4px solid var(--bg-color);
}

.step-icon {
  font-size: 3rem;
  color: var(--primary);
  margin-bottom: 24px;
}

.step-card h3 {
  margin-bottom: 12px;
  font-size: 1.5rem;
}

/* Section 3: Feature Highlights */
.features {
  padding: 80px 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--card-bg);
  padding: 32px;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-soft);
  display: flex;
  align-items: flex-start;
  gap: 16px;
  transition: transform 0.3s;
}

.feature-card:hover {
  transform: translateY(-5px);
}

.feature-icon {
  background: rgba(59, 130, 246, 0.1);
  color: var(--primary);
  padding: 16px;
  border-radius: 16px;
  font-size: 2rem;
}

.feature-card h3 {
  margin-bottom: 8px;
}

/* Section 4: Value Prop */
.value-prop {
  padding: 80px 0;
  text-align: center;
  background: var(--card-bg);
  margin: 40px 0;
  transform: skewY(-2deg);
}

.value-prop > * {
  transform: skewY(2deg);
}

.value-prop h2 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  max-width: 800px;
  margin: 0 auto;
}

/* Section 5: Student Benefits */
.benefits {
  padding: 80px 0;
}

.benefits-content {
  display: flex;
  align-items: center;
  gap: 48px;
  flex-wrap: wrap;
}

.benefits-text {
  flex: 1;
  min-width: 300px;
}

.benefits-list {
  list-style: none;
}

.benefits-list li {
  font-size: 1.25rem;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.benefits-list i {
  color: var(--secondary);
  font-size: 1.5rem;
}

.benefits-image {
  flex: 1;
  min-width: 300px;
  background: var(--gradient-btn);
  border-radius: var(--border-radius);
  padding: 4px;
  transform: rotate(2deg);
  transition: transform 0.3s;
}

.benefits-image:hover {
  transform: rotate(0deg);
}

.benefits-image-inner {
  background: var(--card-bg);
  border-radius: calc(var(--border-radius) - 4px);
  padding: 40px;
  text-align: center;
}

.benefits-image-inner i {
  font-size: 5rem;
  background: var(--gradient-btn);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Footer */
footer {
  text-align: center;
  padding: 40px 0;
  color: var(--text-secondary);
}

/* Responsive Utilities */
@media (max-width: 768px) {
  .hero-ctas {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - 48px);
    z-index: 100;
  }
  
  .hero-ctas .btn {
    width: 100%;
    margin-bottom: 8px;
  }
  
  .chat-input-wrapper {
    margin-bottom: 120px; /* Space for sticky CTAs */
  }
  
  .benefits-content {
    flex-direction: column;
  }
}