/* ===== CSS Variables ===== */
:root {
  --deep-blue: #0A1F3F;
  --primary-blue: #1A3A6B;
  --accent-blue: #2E6BCC;
  --light-blue: #E8F0FE;
  --pale-blue: #F4F8FF;
  --white: #FFFFFF;
  --gray-50: #F9FAFB;
  --gray-100: #F3F4F6;
  --gray-200: #E5E7EB;
  --gray-300: #D1D5DB;
  --gray-400: #9CA3AF;
  --gray-500: #6B7280;
  --gray-600: #4B5563;
  --gray-700: #374151;
  --gray-800: #1F2937;
  --gray-900: #111827;
  --success: #10B981;
  --font-heading: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-body: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --max-width: 1200px;
  --header-height: 72px;
  --transition: 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  color: var(--gray-800);
  background: var(--white);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  text-decoration: none;
  color: inherit;
}

ul, ol {
  list-style: none;
}

img {
  max-width: 100%;
  display: block;
}

/* ===== Typography ===== */
h1 { font-size: 2.75rem; font-weight: 700; line-height: 1.2; }
h2 { font-size: 2rem; font-weight: 700; line-height: 1.3; }
h3 { font-size: 1.5rem; font-weight: 600; line-height: 1.4; }
h4 { font-size: 1.125rem; font-weight: 600; line-height: 1.5; }

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

/* ===== Header ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--gray-200);
  z-index: 1000;
  transition: var(--transition);
}

.header.scrolled {
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.375rem;
  font-weight: 700;
  color: var(--deep-blue);
}

.logo-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--accent-blue), var(--primary-blue));
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.logo-icon svg {
  width: 22px;
  height: 22px;
  fill: var(--white);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-menu a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--gray-600);
  transition: var(--transition);
  position: relative;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--accent-blue);
}

.nav-menu a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--accent-blue);
  border-radius: 1px;
}

.nav-cta {
  padding: 10px 24px;
  background: var(--accent-blue);
  color: var(--white) !important;
  border-radius: 8px;
  font-weight: 600;
  transition: var(--transition);
}

.nav-cta:hover {
  background: var(--primary-blue);
}

.nav-cta::after {
  display: none !important;
}

/* Mobile menu toggle */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
  background: none;
  border: none;
}

.menu-toggle span {
  width: 24px;
  height: 2px;
  background: var(--deep-blue);
  border-radius: 2px;
  transition: var(--transition);
}

/* ===== Sections ===== */
section {
  padding: 100px 0;
}

.section-label {
  display: inline-block;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--accent-blue);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 12px;
}

.section-title {
  font-size: 2rem;
  color: var(--deep-blue);
  margin-bottom: 16px;
}

.section-desc {
  font-size: 1.0625rem;
  color: var(--gray-500);
  max-width: 640px;
  line-height: 1.8;
}

.section-header {
  text-align: center;
  margin-bottom: 64px;
}

.section-header .section-desc {
  margin: 0 auto;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.btn-primary {
  background: var(--accent-blue);
  color: var(--white);
}

.btn-primary:hover {
  background: var(--primary-blue);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(46, 107, 204, 0.3);
}

.btn-outline {
  background: transparent;
  color: var(--accent-blue);
  border: 2px solid var(--accent-blue);
}

.btn-outline:hover {
  background: var(--accent-blue);
  color: var(--white);
}

.btn-white {
  background: var(--white);
  color: var(--primary-blue);
}

.btn-white:hover {
  background: var(--light-blue);
  transform: translateY(-1px);
}

/* ===== Cards ===== */
.card {
  background: var(--white);
  border-radius: 16px;
  padding: 32px;
  border: 1px solid var(--gray-200);
  transition: var(--transition);
}

.card:hover {
  border-color: var(--accent-blue);
  box-shadow: 0 8px 32px rgba(46, 107, 204, 0.1);
  transform: translateY(-4px);
}

/* ===== Grid ===== */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

/* ===== Footer ===== */
.footer {
  background: var(--deep-blue);
  color: var(--gray-300);
  padding: 64px 0 32px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-brand {
  max-width: 300px;
}

.footer-brand .logo {
  color: var(--white);
  margin-bottom: 16px;
}

.footer-brand p {
  font-size: 0.875rem;
  line-height: 1.8;
  color: var(--gray-400);
}

.footer-col h4 {
  color: var(--white);
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 20px;
}

.footer-col a {
  display: block;
  font-size: 0.875rem;
  color: var(--gray-400);
  margin-bottom: 12px;
  transition: var(--transition);
}

.footer-col a:hover {
  color: var(--white);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 24px;
  text-align: center;
  font-size: 0.8125rem;
  color: var(--gray-500);
}

/* ===== Icon Box ===== */
.icon-box {
  width: 56px;
  height: 56px;
  background: var(--light-blue);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.icon-box svg {
  width: 28px;
  height: 28px;
  stroke: var(--accent-blue);
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ===== Stats ===== */
.stat-number {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--accent-blue);
  line-height: 1;
  margin-bottom: 8px;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--gray-500);
}

/* ===== Page Hero ===== */
.page-hero {
  padding: 160px 0 80px;
  background: linear-gradient(180deg, var(--pale-blue) 0%, var(--white) 100%);
  text-align: center;
}

.page-hero h1 {
  color: var(--deep-blue);
  margin-bottom: 16px;
}

.page-hero p {
  font-size: 1.125rem;
  color: var(--gray-500);
  max-width: 600px;
  margin: 0 auto;
}

/* ===== Animations ===== */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  h1 { font-size: 2.25rem; }
  h2 { font-size: 1.75rem; }
  section { padding: 80px 0; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); gap: 32px; }
}

@media (max-width: 768px) {
  h1 { font-size: 1.875rem; }
  h2 { font-size: 1.5rem; }
  section { padding: 64px 0; }

  .nav-menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: 100%;
    background: var(--white);
    flex-direction: column;
    padding: 24px;
    gap: 0;
    border-bottom: 1px solid var(--gray-200);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: var(--transition);
  }

  .nav-menu.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

  .nav-menu a {
    padding: 12px 0;
    width: 100%;
    font-size: 1rem;
  }

  .nav-cta {
    text-align: center;
    margin-top: 8px;
  }

  .menu-toggle {
    display: flex;
  }

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }

  .grid-4 {
    grid-template-columns: 1fr;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .page-hero {
    padding: 120px 0 60px;
  }
}

@media (max-width: 480px) {
  h1 { font-size: 1.625rem; }
  .container { padding: 0 16px; }
  .btn { padding: 12px 24px; font-size: 0.9375rem; }
}