/* ============================================================
   SAYONI MAITI — Custom Stylesheet
   Stack: Tailwind CSS (CDN) + this file
   ============================================================ */

/* Base font */
body {
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* ============================================================
   GRADIENT UTILITIES
   ============================================================ */
.gradient-text {
  background: linear-gradient(135deg, #7c3aed 0%, #4f46e5 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  color: transparent;
}

.gradient-text-teal {
  background: linear-gradient(135deg, #0d9488 0%, #0891b2 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  color: transparent;
}

/* ============================================================
   HERO SECTION
   ============================================================ */
.hero-gradient {
  position: relative;
  overflow: hidden;

  background-image:
    linear-gradient(
      135deg,
      rgba(55, 14, 140, 0.38) 0%,
      rgba(67, 56, 202, 0.38) 45%,
      rgba(6, 95, 88, 0.38) 100%
    ),
    url("../images/hero-bg-iisc.jpg");

  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;

  min-height: 100svh;

  transform: translateZ(0);
  will-change: transform;
}

/* Desktop only */
@media (min-width: 1024px) {
  .hero-gradient {
    background-attachment: fixed;
  }
}

.hero-gradient::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(ellipse at 50% 100%, rgba(0,0,0,0.35) 0%, transparent 70%);
  pointer-events: none;
}

/* Inner page header */
.page-hero {
  background: linear-gradient(135deg, #6d28d9 0%, #4f46e5 70%, #0d9488 100%);
  padding-top: 6rem;
  padding-bottom: 3.5rem;
  position: relative;
  overflow: hidden;
}

.page-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at 10% 50%, rgba(255,255,255,0.06) 0%, transparent 50%),
                    radial-gradient(circle at 90% 30%, rgba(255,255,255,0.06) 0%, transparent 40%);
  pointer-events: none;
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.8rem 2.2rem;
  background: white;
  color: #7c3aed;
  font-weight: 700;
  border-radius: 9999px;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.18);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.25);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.8rem 2.2rem;
  background: transparent;
  color: white;
  font-weight: 700;
  border-radius: 9999px;
  font-size: 0.95rem;
  text-decoration: none;
  border: 2px solid rgba(255, 255, 255, 0.65);
  transition: transform 0.2s ease, background 0.2s ease, border-color 0.2s ease;
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.15);
  border-color: white;
  transform: translateY(-2px);
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.nav-link {
  position: relative;
  color: #475569;
  font-weight: 500;
  font-size: 0.9rem;
  text-decoration: none;
  transition: color 0.2s ease;
}

.nav-link:hover,
.nav-link.active {
  color: #7c3aed;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  border-radius: 1px;
  background: linear-gradient(90deg, #7c3aed, #4f46e5);
  transition: width 0.25s ease;
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* Mobile nav links: no underline pseudo-element */
.mobile-nav-link {
  display: block;
  padding: 0.6rem 0.75rem;
  border-radius: 0.5rem;
  color: #475569;
  font-weight: 500;
  font-size: 0.95rem;
  text-decoration: none;
  transition: background 0.15s ease, color 0.15s ease;
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
  background: #f5f3ff;
  color: #7c3aed;
}

/* ============================================================
   CARDS
   ============================================================ */
.card-hover {
  transition: transform 0.22s ease, box-shadow 0.22s ease;
}

.card-hover:hover {
  transform: translateY(-3px);
  box-shadow: 0 14px 36px rgba(124, 58, 237, 0.13);
}

/* ============================================================
   RESEARCH TAGS (Home page)
   ============================================================ */
.research-tag {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.65rem 1rem;
  border-radius: 0.75rem;
  background: white;
  border: 1.5px solid #e2e8f0;
  font-size: 0.82rem;
  font-weight: 600;
  color: #4f46e5;
  text-align: center;
  transition: all 0.2s ease;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.05);
}

.research-tag:hover {
  border-color: #7c3aed;
  background: #faf5ff;
  transform: translateY(-1px);
}

/* ============================================================
   DEGREE BADGES
   ============================================================ */
.degree-badge {
  display: inline-block;
  padding: 0.22rem 0.8rem;
  border-radius: 9999px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

/* ============================================================
   SCROLL REVEAL ANIMATIONS
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

.delay-100 { transition-delay: 0.1s; }
.delay-200 { transition-delay: 0.2s; }
.delay-300 { transition-delay: 0.3s; }
.delay-400 { transition-delay: 0.4s; }
.delay-500 { transition-delay: 0.5s; }

/* ============================================================
   TIMELINE (Teaching page)
   ============================================================ */
.timeline-item {
  position: relative;
  padding-left: 2.5rem;
  padding-bottom: 2.25rem;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 5px;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  background: linear-gradient(135deg, #7c3aed, #4f46e5);
  z-index: 1;
  box-shadow: 0 0 0 3px #ede9fe;
}

.timeline-item::after {
  content: '';
  position: absolute;
  left: 6px;
  top: 18px;
  width: 2px;
  height: calc(100% - 6px);
  background: linear-gradient(to bottom, #c4b5fd, #e2e8f0);
}

.timeline-item:last-child::after {
  display: none;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

/* ============================================================
   PUBLICATIONS
   ============================================================ */
.pub-entry {
  border-left: 3px solid #e2e8f0;
  padding-left: 1.25rem;
  transition: border-color 0.2s ease, background 0.2s ease;
  border-radius: 0 0.5rem 0.5rem 0;
}

.pub-entry:hover {
  border-color: #7c3aed;
  background: #faf5ff;
}

.pub-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 600;
  color: #7c3aed;
  background: #ede9fe;
  text-decoration: none;
  transition: background 0.15s ease, color 0.15s ease;
}

.pub-link:hover {
  background: #7c3aed;
  color: white;
}

.pub-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.75rem;
  height: 1.75rem;
  border-radius: 50%;
  background: linear-gradient(135deg, #7c3aed, #4f46e5);
  color: white;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
}

/* ============================================================
   SKILL TAGS (Research page)
   ============================================================ */
.skill-tag {
  display: inline-flex;
  align-items: center;
  padding: 0.3rem 0.8rem;
  border-radius: 0.5rem;
  background: #f1f5f9;
  color: #475569;
  font-size: 0.78rem;
  font-weight: 500;
  margin: 0.18rem;
  transition: all 0.15s ease;
}

.skill-tag:hover {
  background: #ede9fe;
  color: #7c3aed;
}

/* ============================================================
   SECTION HEADING UTILITY
   ============================================================ */
.section-label {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: #7c3aed;
  margin-bottom: 0.6rem;
}

/* ============================================================
   CONTACT PAGE
   ============================================================ */
.contact-card {
  background: white;
  border-radius: 1.25rem;
  padding: 2rem;
  border: 1px solid #e2e8f0;
  transition: box-shadow 0.2s ease;
}

.contact-card:hover {
  box-shadow: 0 8px 24px rgba(124, 58, 237, 0.1);
}

/* ============================================================
   MENTORSHIP CARD (Teaching page)
   ============================================================ */
.mentorship-card {
  border-top: 3px solid #7c3aed;
  background: white;
  border-radius: 0 0 1rem 1rem;
}

/* ============================================================
   CUSTOM SCROLLBAR
   ============================================================ */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: #f1f5f9;
}

::-webkit-scrollbar-thumb {
  background: #c4b5fd;
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: #7c3aed;
}