/* =========================================
   Interactive / Motion Enhancements
   ========================================= */

:root {
  --motion-ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* Smooth scroll is handled natively by the page's links and JS. */
html {
  scroll-behavior: smooth;
}

/* ---------- Navbar ---------- */
header {
  transition:
    box-shadow 0.35s ease,
    background-color 0.35s ease,
    transform 0.35s var(--motion-ease);
}

header.is-scrolled {
  background: rgba(255, 255, 255, 0.96);
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.12);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}

/* Progress bar sits directly at the bottom edge of the navbar. */
.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 3px;
  overflow: hidden;
  background: rgba(37, 99, 235, 0.08);
  pointer-events: none;
}

#scroll-progress-bar {
  display: block;
  width: 0;
  height: 100%;
  border-radius: 0 999px 999px 0;
  background: linear-gradient(90deg, #60a5fa 0%, #2563eb 55%, #1d4ed8 100%);
  box-shadow: 0 0 10px rgba(37, 99, 235, 0.35);
  transition: width 0.08s linear;
}

/* ---------- Hero ---------- */
#hero {
  isolation: isolate;
  background: #0f172a;
}

#hero .hero-image {
  position: absolute;
  inset: -2%;
  width: 104%;
  height: 104%;
  max-width: none;
  z-index: 0;
  object-fit: cover;
  transform: scale(1.01);
  transform-origin: center center;
  animation: heroSlowZoom 22s var(--motion-ease) infinite alternate;
  will-change: transform;
  filter: saturate(1.04) contrast(1.02);
}

#hero .hero-bg {
  z-index: 1;
  opacity: 0.76;
  background:
    radial-gradient(
      circle at 20% 25%,
      rgba(96, 165, 250, 0.24),
      transparent 28%
    ),
    radial-gradient(
      circle at 78% 72%,
      rgba(30, 64, 175, 0.22),
      transparent 30%
    ),
    var(--linear-color);
  background-size:
    120% 120%,
    130% 130%,
    100% 100%;
  animation: heroGradientDrift 18s ease-in-out infinite alternate;
  pointer-events: none;
}

#hero::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 2;
  pointer-events: none;
  background: linear-gradient(
    180deg,
    rgba(15, 23, 42, 0.03) 0%,
    rgba(15, 23, 42, 0.05) 45%,
    rgba(15, 23, 42, 0.24) 100%
  );
}

.hero-particles {
  position: absolute;
  inset: 0;
  z-index: 3;
  overflow: hidden;
  pointer-events: none;
}

.hero-particle {
  position: absolute;
  left: var(--x);
  top: var(--y);
  width: var(--size);
  height: var(--size);
  border-radius: 50%;
  background: rgba(219, 234, 254, 0.42);
  opacity: 0.28;
  box-shadow: 0 0 10px rgba(147, 197, 253, 0.18);
  animation: particleFloat var(--duration) ease-in-out var(--delay) infinite
    alternate;
  will-change: transform, opacity;
}

@keyframes heroSlowZoom {
  0% {
    transform: scale(1.01);
  }
  100% {
    transform: scale(1.075);
  }
}

@keyframes heroGradientDrift {
  0% {
    background-position:
      0% 0%,
      100% 100%,
      0% 50%;
  }
  100% {
    background-position:
      15% 10%,
      85% 90%,
      100% 50%;
  }
}

@keyframes particleFloat {
  0% {
    transform: translate3d(0, 0, 0) scale(0.9);
    opacity: 0.14;
  }
  50% {
    opacity: 0.32;
  }
  100% {
    transform: translate3d(var(--drift-x), var(--drift-y), 0) scale(1.12);
    opacity: 0.08;
  }
}

/* Make hero content sit above the visual layers. */
#hero > div:not(.hero-bg):not(.hero-particles) {
  z-index: 10;
}

/* ---------- Scroll to top ---------- */
.scroll-to-top {
  position: fixed;
  right: 28px;
  bottom: 28px;
  z-index: 120;
  width: 46px;
  height: 46px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 999px;
  color: #fff;
  background: rgba(37, 99, 235, 0.88);
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.18);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(14px) scale(0.84);
  transition:
    opacity 0.3s ease,
    visibility 0.3s ease,
    transform 0.3s var(--motion-ease),
    background-color 0.25s ease,
    box-shadow 0.25s ease;
}

.scroll-to-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

.scroll-to-top:hover {
  background: #1d4ed8;
  transform: translateY(-3px) scale(1.04);
  box-shadow: 0 14px 32px rgba(37, 99, 235, 0.28);
}

.scroll-to-top:active {
  transform: translateY(0) scale(0.96);
}

.scroll-to-top i {
  font-size: 16px;
}

/* ---------- Subtle card motion ---------- */
.anggota .card,
#divisi .card,
.kegiatan .card,
.contact-card,
.faq-item {
  transition:
    transform 0.35s var(--motion-ease),
    box-shadow 0.35s ease,
    border-color 0.35s ease;
}

.anggota .card:hover,
#divisi .card:hover,
.kegiatan .card:hover {
  box-shadow: 0 16px 34px rgba(15, 23, 42, 0.12);
}

/* ---------- Accessibility ---------- */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

@media (max-width: 768px) {
  #hero .hero-image {
    width: 108%;
    height: 108%;
    inset: -4%;
  }

  .scroll-to-top {
    right: 18px;
    bottom: 18px;
    width: 44px;
    height: 44px;
  }

  .scroll-progress {
    height: 2px;
  }
}