/* ============================================
   연세세브란스치과 — Custom Styles
   ============================================ */

*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Scrollbar ─────────────────────────────── */
::-webkit-scrollbar { width: 5px; }
::-webkit-scrollbar-track { background: #f0f0f0; }
::-webkit-scrollbar-thumb { background: #003876; border-radius: 3px; }

/* ── Header ────────────────────────────────── */
#header {
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background 0.5s ease, border-color 0.5s ease, box-shadow 0.5s ease;
}

#header.scrolled {
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-bottom-color: rgba(0, 0, 0, 0.06);
  box-shadow: 0 2px 24px rgba(0, 0, 0, 0.06);
}

#header.scrolled .header-logo-sub { color: #6b7280; }
#header.scrolled .header-logo-main { color: #111827; }

/* ── Hamburger Animation ───────────────────── */
.ham-line {
  display: block;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
  transition: transform 0.35s cubic-bezier(0.23, 1, 0.32, 1),
              opacity 0.25s ease,
              width 0.25s ease;
  transform-origin: center;
}

#hamburger.open .ham-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
#hamburger.open .ham-line:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}
#hamburger.open .ham-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Mobile Menu ───────────────────────────── */
#mobile-menu {
  transform: translateX(100%);
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}
#mobile-menu.open { transform: translateX(0); }

/* ── Fade-In Scroll Animations ─────────────── */
.fade-in-up {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.85s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.85s cubic-bezier(0.16, 1, 0.3, 1);
}
.fade-in-up.visible {
  opacity: 1;
  transform: translateY(0);
}

.fade-in-up.delay-100 { transition-delay: 0.1s; }
.fade-in-up.delay-200 { transition-delay: 0.2s; }
.fade-in-up.delay-300 { transition-delay: 0.3s; }

/* ── Hero Parallax ─────────────────────────── */
#hero-bg {
  will-change: transform;
  transition: transform 0s linear;
}

/* ── Floating Buttons ──────────────────────── */
.float-wrap {
  animation: floatIn 0.7s cubic-bezier(0.16, 1, 0.3, 1) 1s both;
}
@keyframes floatIn {
  from { opacity: 0; transform: translateY(30px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Service Card Hover ─────────────────────── */
.service-card {
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1),
              box-shadow 0.5s ease;
}
.service-card:hover { transform: translateY(-10px); }

/* ── Equipment Image ────────────────────────── */
.equip-img {
  transition: transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}
.equip-card:hover .equip-img { transform: scale(1.06); }

/* ── Nav active link ────────────────────────── */
.nav-link {
  position: relative;
  padding-bottom: 2px;
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: #003876;
  transition: width 0.3s ease;
}
.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}
.nav-link.active { color: #003876; }

/* ── Stat number animation ──────────────────── */
.stat-num {
  font-variant-numeric: tabular-nums;
}

/* ── Mobile touch targets ───────────────────── */
@media (max-width: 768px) {
  .float-btn-text { display: none; }
  .float-wrap-btn {
    width: 52px;
    height: 52px;
    border-radius: 50%;
    padding: 0;
    justify-content: center;
  }
}

/* ── Side Navigation ────────────────────────── */
.side-dot {
  position: relative;
  z-index: 1;
  display: block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  border: 2px solid rgba(255,255,255,0.35);
  background: transparent;
  flex-shrink: 0;
  transition: border-color 0.3s ease,
              background 0.3s ease,
              transform 0.3s ease;
}

.side-nav-label {
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.45);
  white-space: nowrap;
  font-weight: 700;
  transition: color 0.25s ease;
}

/* hover */
.side-nav-link:hover .side-dot {
  border-color: rgba(255,255,255,0.8);
  transform: scale(1.2);
}
.side-nav-link:hover .side-nav-label { color: rgba(255,255,255,0.9); }

/* active */
.side-nav-link.active .side-dot {
  background: #fff;
  border-color: #fff;
  transform: scale(1.3);
  box-shadow: 0 0 0 3px rgba(255,255,255,0.15);
}
.side-nav-link.active .side-nav-label {
  color: #fff;
  font-weight: 700;
}

/* ── Dark background mode (hero, location) ── */
#side-nav.on-dark .side-track { background: rgba(255,255,255,0.25); }

#side-nav.on-dark .side-dot {
  border-color: rgba(255,255,255,0.55);
  background: transparent;
}
#side-nav.on-dark .side-nav-label { color: rgba(255,255,255,0.75); }

#side-nav.on-dark .side-nav-link:hover .side-dot {
  border-color: #fff;
  background: rgba(255,255,255,0.15);
}
#side-nav.on-dark .side-nav-link:hover .side-nav-label { color: #fff; }

#side-nav.on-dark .side-nav-link.active .side-dot {
  background: #fff;
  border-color: #fff;
  box-shadow: 0 0 0 3px rgba(255,255,255,0.2);
}
#side-nav.on-dark .side-nav-link.active .side-nav-label {
  color: #fff;
  font-weight: 700;
}

/* ── FAQ Accordion ───────────────────────────── */
.faq-item summary { list-style: none; }
.faq-item summary::-webkit-details-marker { display: none; }

.faq-plus {
  font-size: 1.25rem;
  line-height: 1;
  color: #d1d5db;
  flex-shrink: 0;
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), color 0.2s ease;
}
details[open] .faq-plus {
  transform: rotate(45deg);
  color: #9ca3af;
}

.faq-body {
  display: block;
  overflow: hidden;
  max-height: 0;
  opacity: 0;
  transition: max-height 0.35s ease, opacity 0.25s ease;
}
details[open] > .faq-body {
  max-height: 600px;
  opacity: 1;
}

/* ── Mobile Bottom Tab Bar ──────────────────── */
.tab-link {
  color: #7A6045;
  transition: color 0.2s ease;
}
.tab-link.active {
  color: #C9935A;
}
.tab-link svg {
  transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}
.tab-link.active svg {
  transform: translateY(-1px);
}

/* ── Utility ────────────────────────────────── */
.text-balance { text-wrap: balance; }
.section-label {
  font-size: 0.65rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  font-weight: 600;
}