/* ===========================
   CSS RESET & BASE STYLES
   =========================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Light Mode Colors */
  --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --secondary-gradient: linear-gradient(120deg, #a1c4fd 0%, #c2e9fb 100%);
  --accent-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --warm-gradient: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
  --cool-gradient: linear-gradient(135deg, #30cfd0 0%, #330867 100%);

  /* Text Colors */
  --text-primary: #1a1a2e;
  --text-secondary: #4a5568;
  --text-light: #718096;
  --text-on-dark: #f7fafc;

  /* Background Colors */
  --bg-light: #ffffff;
  --bg-subtle: #f7fafc;
  --bg-gray: #edf2f7;

  /* Card & UI */
  --card-bg: #ffffff;
  --card-shadow: 0 10px 40px rgba(0, 0, 0, 0.08);
  --card-shadow-hover: 0 20px 60px rgba(0, 0, 0, 0.12);

  /* Borders & Accents */
  --border-color: #e2e8f0;
  --accent-color: #667eea;
}

:root.dark-mode,
html.dark-mode {
  /* Dark Mode Colors */
  --primary-gradient: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
  --secondary-gradient: linear-gradient(120deg, #2d3748 0%, #1a202c 100%);
  --accent-gradient: linear-gradient(135deg, #b794f6 0%, #f687b3 100%);
  --warm-gradient: linear-gradient(135deg, #ed64a6 0%, #f6ad55 100%);
  --cool-gradient: linear-gradient(135deg, #4299e1 0%, #2d3748 100%);

  --text-primary: #f7fafc;
  --text-secondary: #e2e8f0;
  --text-light: #cbd5e0;
  --text-on-dark: #f7fafc;

  --bg-light: #1a202c;
  --bg-subtle: #2d3748;
  --bg-gray: #1a1a2e;

  --card-bg: #2d3748;
  --card-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
  --card-shadow-hover: 0 20px 60px rgba(0, 0, 0, 0.4);

  --border-color: #4a5568;
  --accent-color: #b794f6;
}

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

/* ===========================
   BACK BUTTON & HEADER
   =========================== */
.page-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--bg-light);
  border-bottom: 1px solid var(--border-color);
  padding: 16px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-shrink: 0;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.header-title {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 10px;
}

.header-logo {
  width: 28px;
  height: 28px;
  display: block;
}

.theme-toggle {
  background: none;
  border: none;
  font-size: 18px;
  cursor: pointer;
  padding: 6px;
  border-radius: 50%;
  transition: background-color 0.2s;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  user-select: none;
}

.theme-toggle:hover {
  background: rgba(0, 0, 0, 0.1);
}

.dark-mode .theme-toggle:hover {
  background: rgba(255, 255, 255, 0.1);
}

.soft-back-btn {
  text-decoration: none;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
  opacity: 0.6;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  padding: 8px;
  border-radius: 50%;
}

.soft-back-btn:hover {
  opacity: 1;
  background: rgba(0, 0, 0, 0.05);
}

.dark-mode .soft-back-btn {
  opacity: 0.9;
}

.dark-mode .soft-back-btn:hover {
  background: rgba(255, 255, 255, 0.1);
}

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

/* ===========================
   HERO SECTION
   =========================== */
.hero {
  background: var(--primary-gradient);
  color: white;
  text-align: center;
  padding: 100px 24px 100px;
  padding-top: 120px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  opacity: 0.3;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 700;
  margin-bottom: 24px;
  letter-spacing: -0.02em;
  animation: fadeInUp 0.8s ease-out;
}

.hero-subtitle {
  font-size: 1.25rem;
  font-weight: 400;
  max-width: 700px;
  margin: 0 auto;
  opacity: 0.95;
  line-height: 1.8;
  animation: fadeInUp 0.8s ease-out 0.2s both;
}

/* ===========================
   SECTION COMMONS
   =========================== */
section {
  padding: 80px 0;
}

section h2 {
  font-size: 2.75rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 16px;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.section-intro {
  text-align: center;
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 800px;
  margin: 0 auto 60px;
  line-height: 1.8;
}

/* ===========================
   PSYCHOLOGY SECTION
   =========================== */
.psychology {
  background: var(--bg-light);
  padding: 100px 0;
}

.psychology-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 32px;
  margin-bottom: 60px;
}

.psychology-card {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 32px;
  box-shadow: var(--card-shadow);
  transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid var(--border-color);
}

.psychology-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--card-shadow-hover);
  border-color: var(--accent-color);
}

.card-icon {
  font-size: 3rem;
  margin-bottom: 16px;
  display: inline-block;
  animation: float 3s ease-in-out infinite;
}

.psychology-card h3 {
  font-size: 1.375rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.psychology-card p {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.psychology-footer {
  background: var(--bg-subtle);
  border-left: 4px solid var(--accent-color);
  padding: 24px 32px;
  border-radius: 12px;
  margin-top: 40px;
}

.psychology-footer p {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.8;
}

/* ===========================
   FEATURES SECTION
   =========================== */
.features {
  background: var(--bg-subtle);
  padding: 100px 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 28px;
}

.feature-card {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 28px;
  box-shadow: var(--card-shadow);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid var(--border-color);
  text-align: center;
}

.feature-card:hover {
  transform: translateY(-6px) scale(1.02);
  box-shadow: var(--card-shadow-hover);
}

.feature-icon {
  font-size: 2.5rem;
  margin-bottom: 16px;
  display: inline-block;
  filter: grayscale(0);
  transition: filter 0.3s;
}

.feature-card:hover .feature-icon {
  filter: drop-shadow(0 0 8px rgba(102, 126, 234, 0.4));
}

.feature-card h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.feature-card p {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ===========================
   BENEFITS SECTION
   =========================== */
.benefits {
  background: var(--primary-gradient);
  color: white;
  padding: 100px 0;
  position: relative;
  overflow: hidden;
}

.benefits::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 20% 50%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 80% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.benefits-content {
  position: relative;
  z-index: 1;
  max-width: 900px;
  margin: 0 auto;
}

.benefits h2 {
  color: white;
  margin-bottom: 32px;
}

.benefits-content>p {
  font-size: 1.125rem;
  text-align: center;
  margin-bottom: 40px;
  opacity: 0.95;
  line-height: 1.8;
}

.benefits-list {
  list-style: none;
  padding: 0;
  display: grid;
  gap: 20px;
}

.benefits-list li {
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
  padding: 20px 24px;
  border-radius: 12px;
  font-size: 1.0625rem;
  border: 1px solid rgba(255, 255, 255, 0.2);
  transition: all 0.3s;
}

.benefits-list li:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: translateX(8px);
}

.benefits-list strong {
  color: #fff;
  font-weight: 600;
}

/* ===========================
   CTA SECTION
   =========================== */
.cta {
  background: var(--bg-light);
  padding: 100px 0;
  text-align: center;
}

.cta h2 {
  margin-bottom: 20px;
}

.cta p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: 40px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.cta-button {
  display: inline-block;
  background: var(--primary-gradient);
  color: white;
  padding: 16px 48px;
  border-radius: 50px;
  text-decoration: none;
  font-size: 1.125rem;
  font-weight: 600;
  box-shadow: 0 10px 30px rgba(102, 126, 234, 0.3);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.cta-button:hover {
  transform: translateY(-3px);
  box-shadow: 0 15px 40px rgba(102, 126, 234, 0.4);
}

/* ===========================
   ANIMATIONS
   =========================== */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes float {

  0%,
  100% {
    transform: translateY(0);
  }

  50% {
    transform: translateY(-10px);
  }
}

/* ===========================
   RESPONSIVE DESIGN
   =========================== */
@media (max-width: 768px) {
  .page-header {
    padding: 12px 12px;
    gap: 8px;
  }

  .header-left {
    gap: 2px;
  }

  .header-title {
    font-size: 16px;
  }

  .header-logo {
    width: 24px;
    height: 24px;
  }

  .soft-back-btn {
    padding: 6px;
  }

  .hero {
    padding: 100px 20px 70px;
  }

  .hero h1 {
    font-size: 2.25rem;
  }

  .hero-subtitle {
    font-size: 1.0625rem;
  }

  section h2 {
    font-size: 2rem;
  }

  .section-intro {
    font-size: 1rem;
  }

  .psychology-grid,
  .features-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .floating-back {
    top: 16px;
    left: 16px;
  }

  section {
    padding: 60px 0;
  }

  .psychology,
  .features,
  .benefits,
  .cta {
    padding: 70px 0;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.875rem;
  }

  .psychology-card,
  .feature-card {
    padding: 24px;
  }

  .cta-button {
    padding: 14px 36px;
    font-size: 1rem;
  }
}