/* =============================
   GLOBAL SETTINGS
============================= */
body {
  font-family: 'Noto Sans KR', 'Outfit', sans-serif;
  margin: 0;
  padding: 0;
  background: #f9fbff;
  color: #222;
  overflow-x: hidden;
  scroll-behavior: smooth;
}
* {
  box-sizing: border-box;
}

/* =============================
   NAVIGATION BAR
============================= */
.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 48px;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
  transition: background 0.3s ease;
}
.navbar-left {
  display: flex;
  align-items: center;
}
.navbar-left img {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  margin-right: 10px;
}
.navbar-left span {
  font-size: 22px;
  font-weight: 800;
  color: #0050c8;
  letter-spacing: 0.5px;
}
.navbar-right a {
  margin-left: 26px;
  font-weight: 500;
  text-decoration: none;
  color: #004aad;
  position: relative;
  transition: 0.25s;
}
.navbar-right a:hover {
  color: #007bff;
}
.navbar-right a::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: #007bff;
  transition: width 0.3s ease;
}
.navbar-right a:hover::after {
  width: 100%;
}

/* =============================
   HERO SECTION
============================= */
.hero {
  position: relative;
  height: 90vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
  color: #fff;
  background: radial-gradient(circle at 30% 20%, #0056d6, #001d5e);
}
.hero-bg {
  position: absolute;
  inset: 0;
  background-image: url("https://upload.wikimedia.org/wikipedia/commons/9/90/Math_equation_background.png");
  background-size: cover;
  opacity: 0.05;
}
.hero-glow {
  position: absolute;
  width: 100%;
  height: 100%;
  z-index: 1;
  background: radial-gradient(circle at 50% 50%, rgba(0, 150, 255, 0.25), transparent 70%);
  transition: background 0.2s ease;
}
#symbolCanvas {
  position: absolute;
  inset: 0;
  z-index: 0;
  opacity: 0.2;
}
.hero-content {
  position: relative;
  z-index: 2;
  padding: 0 20px;
}
.hero h1 {
  font-size: 3rem;
  line-height: 1.4;
  font-weight: 800;
  margin-bottom: 20px;
}
.hero .highlight {
  color: #00b3ff;
}
.hero p {
  font-size: 1.2rem;
  opacity: 0.9;
}
.hero-buttons {
  margin-top: 35px;
}
.btn-primary,
.btn-secondary {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 8px;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.3s ease;
}
.btn-primary {
  background: #00b3ff;
  color: white;
  box-shadow: 0 0 15px rgba(0, 179, 255, 0.4);
}
.btn-primary:hover {
  background: #008ae6;
  box-shadow: 0 0 25px rgba(0, 179, 255, 0.6);
}
.btn-secondary {
  border: 2px solid #00b3ff;
  color: #00b3ff;
  margin-left: 10px;
}
.btn-secondary:hover {
  background: #00b3ff;
  color: white;
}
.floating-symbols {
  font-size: 40px;
  margin-top: 60px;
  opacity: 0.8;
  display: flex;
  justify-content: center;
  gap: 20px;
}
.floating-symbols span {
  animation: float 3s ease-in-out infinite;
}
.floating-symbols span:nth-child(2) { animation-delay: 0.4s; }
.floating-symbols span:nth-child(3) { animation-delay: 0.8s; }
.floating-symbols span:nth-child(4) { animation-delay: 1.2s; }
@keyframes float {
  0%,100%{transform:translateY(0);}50%{transform:translateY(-10px);}
}
/* 반짝 효과 */
.shine {
  position: relative;
  overflow: hidden;
  display: inline-block;
}
.shine::after {
  content: "";
  position: absolute;
  top: 0;
  left: -75%;
  width: 50%;
  height: 100%;
  background: linear-gradient(120deg, rgba(255,255,255,0) 0%, rgba(255,255,255,0.5) 50%, rgba(255,255,255,0) 100%);
  animation: shine 4s infinite;
}
@keyframes shine {
  0% { left: -75%; }
  100% { left: 125%; }
}

/* =============================
   SECTION BASE
============================= */
.section {
  max-width: 1100px;
  margin: auto;
  padding: 100px 20px;
  text-align: center;
}
.section h2 {
  font-size: 2rem;
  font-weight: 800;
  color: #004aad;
  margin-bottom: 40px;
}
.section p {
  font-size: 1.1rem;
  color: #444;
  line-height: 1.8;
}
.blue {
  color: #007bff;
}

/* =============================
   FEATURES SECTION (IMPROVED)
============================= */
.features-section {
  background: linear-gradient(180deg, #f8faff 0%, #eef4ff 100%);
  padding: 120px 20px;
}
.features-section h2 {
  font-size: 2.2rem;
  font-weight: 800;
  color: #004aad;
  margin-bottom: 60px;
  position: relative;
}
.features-section h2::after {
  content: "";
  position: absolute;
  bottom: -14px;
  left: 50%;
  transform: translateX(-50%);
  width: 80px;
  height: 4px;
  border-radius: 2px;
  background: linear-gradient(90deg, #004aad, #00b3ff);
}
.features {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 30px;
  justify-items: center;
  align-items: stretch;
}
.feature-card {
  background: #fff;
  border-radius: 18px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.05);
  padding: 45px 25px;
  width: 100%;
  max-width: 270px;
  text-align: center;
  transition: transform 0.35s ease, box-shadow 0.35s ease;
  position: relative;
  overflow: hidden;
}
.feature-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(120deg, rgba(0,179,255,0.15), transparent 70%);
  transition: left 0.8s ease;
  z-index: 0;
}
.feature-card:hover::before { left: 100%; }
.feature-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 12px 28px rgba(0,100,255,0.15);
}
.icon-circle {
  width: 90px;
  height: 90px;
  border-radius: 50%;
  background: linear-gradient(135deg, #007bff, #004aad);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 25px auto;
  transition: transform 0.3s ease;
}
.feature-card:hover .icon-circle {
  transform: scale(1.1);
}
.icon-circle img {
  width: 48px;
  filter: brightness(0) invert(1);
}
.feature-card h3 {
  color: #003f9e;
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 10px;
}
.feature-card p {
  color: #555;
  font-size: 15px;
  line-height: 1.7;
  max-width: 240px;
  margin: 0 auto;
}
@media (max-width: 1024px) {
  .features { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .features { grid-template-columns: 1fr; }
  .feature-card { max-width: 330px; }
}

/* =============================
   QUOTE BANNER
============================= */
.quote-banner {
  background: linear-gradient(135deg, #004aad, #007bff);
  color: white;
  text-align: center;
  font-size: 1.4rem;
  padding: 80px 20px;
  font-weight: 600;
  letter-spacing: 0.5px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}

/* =============================
   FAQ
============================= */
.faq-item {
  background: white;
  border-left: 4px solid #007bff;
  border-radius: 12px;
  padding: 25px 30px;
  margin-bottom: 20px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}
.faq-item h3 {
  color: #004aad;
  font-size: 18px;
  margin-bottom: 10px;
}
.faq-item p {
  color: #555;
  margin: 0;
  line-height: 1.7;
}

/* =============================
   CTA
============================= */
.cta {
  background: #e9f1ff;
  text-align: center;
  padding: 100px 20px;
}
.cta h2 {
  color: #004aad;
  font-size: 2rem;
  font-weight: 700;
}
.cta p {
  color: #444;
  margin-bottom: 30px;
}
.download-buttons img {
  width: 180px;
  margin: 0 15px;
  transition: transform 0.2s;
}
.download-buttons img:hover {
  transform: scale(1.08);
}

/* =============================
   FOOTER
============================= */
footer {
  background: #f6f8fb;
  color: #666;
  text-align: center;
  padding: 40px 20px 60px;
  font-size: 14px;
}
footer a {
  color: #004aad;
  text-decoration: none;
  margin: 0 8px;
}
footer a:hover {
  text-decoration: underline;
}
.credit-info {
  margin-top: 25px;
  padding-top: 20px;
  border-top: 1px solid #e0e4ef;
  font-size: 13px;
  color: #999;
  line-height: 1.7;
}
.credit-info a {
  color: #007bff;
  text-decoration: none;
}
.credit-info a:hover {
  text-decoration: underline;
}

/* =============================
   SCROLL ANIMATION
============================= */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}
.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* =============================
   RESPONSIVE (GENERAL)
============================= */
@media (max-width: 768px) {
  .navbar { padding: 12px 20px; }
  .navbar-left span { font-size: 19px; }
  .navbar-right a { margin-left: 14px; font-size: 15px; }
  .hero h1 { font-size: 2rem; }
  .hero p { font-size: 1rem; }
  .btn-primary, .btn-secondary { padding: 10px 22px; }
  .quote-banner { font-size: 1.2rem; padding: 60px 20px; }
  .credit-info { font-size: 12px; }
}