@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500;700&display=swap');

:root {
  --night: #05040d;

  --gold: #d8b56a;
  --mist: #e5ddc5;
  --ink: #15131f;
}

body {
  font-family: 'Roboto', sans-serif;

  background: var(--night);
  color: var(--mist);
}

.hero {
  background-image:
    linear-gradient(to bottom, rgba(5, 4, 13, 0.5), rgba(5, 4, 13, 0.92)),
    url("https://images.unsplash.com/photo-1519681393784-d120267933ba?auto=format&fit=crop&w=1900&q=80");
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
}

.starfield::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at 20% 30%, rgba(255, 255, 255, 0.8) 0.7px, transparent 1px),
    radial-gradient(circle at 70% 40%, rgba(255, 255, 255, 0.55) 0.7px, transparent 1px),
    radial-gradient(circle at 50% 80%, rgba(255, 255, 255, 0.65) 0.7px, transparent 1px),
    radial-gradient(circle at 85% 20%, rgba(255, 255, 255, 0.75) 0.7px, transparent 1px),
    radial-gradient(circle at 12% 75%, rgba(255, 255, 255, 0.6) 0.7px, transparent 1px);
  background-size: 320px 320px;
  opacity: 0.55;
  animation: twinkle 8s linear infinite;
  pointer-events: none;
}

.rise {
  opacity: 0;
  transform: translateY(24px);
  animation: riseIn 1s ease forwards;
}

.rise-delay {
  animation-delay: 0.25s;
}

.rise-delay-2 {
  animation-delay: 0.45s;
}
.rise-delay-3 {
  animation-delay: 0.65s;
}

.line-glow {
  position: relative;
  display: inline-block;
}

.line-glow::after {
  content: "";
  display: block;
  width: 0;
  height: 2px;
  background: var(--gold);
  margin-top: 6px;
  animation: drawLine 1.3s ease forwards;
  animation-delay: 0.9s;
}

a.study-link,
a.social-link {
  transition: color 240ms ease, transform 240ms ease;
}

a.study-link:hover,
a.social-link:hover {
  color: #f4d087;
  transform: translateX(4px);
}

.study4-tab {
  padding-left: 1.5rem;
  border-left: 2px solid rgba(216, 181, 106, 0.3);
  margin-left: 1rem;
}

.study4-tab ul {
  list-style-type: disc;
  padding-left: 1rem;
}

.field-input {
  outline: none;
  transition: border-color 220ms ease, box-shadow 220ms ease;
}

.field-input:focus {
  border-color: rgba(216, 181, 106, 0.85);
  box-shadow: 0 0 0 2px rgba(216, 181, 106, 0.2);
}


/* Lightbox for image zoom - improved */
    .lightbox {
      display: none;
      position: fixed;
      z-index: 1000;
      left: 0;
      top: 0;
      width: 100%;
      height: 100%;
      background-color: rgba(5, 4, 13, 0.95);
      backdrop-filter: blur(4px);
      align-items: center;
      justify-content: center;
    }
    .lightbox.active {
      display: flex;
    }
    .lightbox-img {
      max-width: 90vw;
      max-height: 90vh;
      width: auto;
      height: auto;
      border-radius: 1rem;
      box-shadow: 0 0 60px rgba(216, 181, 106, 0.5);
      cursor: zoom-out;
      transform-origin: center;
      transition: transform 0.3s ease;
    }
    .lightbox-close {
      position: absolute;
      top: 20px;
      right: 30px;
      background: rgba(216, 181, 106, 0.9);
      color: #05040d;
      border: none;
      border-radius: 50%;
      width: 40px;
      height: 40px;
      font-size: 20px;
      font-weight: bold;
      cursor: pointer;
      z-index: 1001;
      transition: background 0.3s ease;
    }
    .lightbox-close:hover {
      background: #d8b56a;
    }
    .indicator-img {
      cursor: pointer !important;
      transition: transform 0.3s ease;
    }
    .indicator-img:hover {
      transform: scale(1.02);
    }

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

@keyframes drawLine {
  to {
    width: 100%;
  }
}

@keyframes twinkle {
  0%,
  100% {
    opacity: 0.45;
  }
  50% {
    opacity: 0.75;
  }
}

/* Smooth scrolling for anchor links */
html {
  scroll-behavior: smooth;
}

/* Indicator link styles - professional nav buttons */
.indicator-link {
  display: inline-block;
  color: var(--mist);
  background: rgba(216, 181, 106, 0.1);
  backdrop-filter: blur(8px);
  font-weight: 500;
  text-decoration: none;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 0.5rem;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.3);
}

.indicator-link:hover {
  background: rgba(216, 181, 106, 0.25);
  border-color: var(--gold);
  color: #f4ead7;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(216, 181, 106, 0.4);
}

/* Back to Top Button */
.top-btn {
  position: fixed;
  bottom: 1.5rem;
  right: 1.5rem;
  background: rgba(216, 181, 106, 0.2);
  backdrop-filter: blur(12px);
  border: 2px solid rgba(216, 181, 106, 0.4);
  color: var(--mist);
  font-family: 'Roboto', sans-serif;
  font-weight: 600;
  font-size: 0.875rem;
  padding: 0.75rem 1rem;
  border-radius: 50px;
  cursor: pointer;
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px) scale(0.95);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
  min-width: 60px;
  text-align: center;
  user-select: none;
}

.top-btn:not(.hidden) {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

.top-btn:hover {
  background: rgba(216, 181, 106, 0.35);
  border-color: var(--gold);
  color: #f4ead7;
  transform: translateY(-3px) scale(1.05);
  box-shadow: 0 8px 30px rgba(216, 181, 106, 0.5);
}

.top-btn:active {
  transform: translateY(-1px) scale(1);
}

/* Mobile adjustments */
@media (max-width: 640px) {
  .top-btn {
    bottom: 1rem;
    right: 1rem;
    padding: 0.625rem 0.875rem;
    font-size: 0.8rem;
    min-width: 52px;
  }
}