/* =============================================
   Dr. S Madhu — Single Page Website
   HTML5 / CSS3 — no framework dependencies
   ============================================= */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --navy:       #0f1e2e;
  --navy-lt:    #1a2f45;
  --navy-mid:   #162032;
  --gold:       #c8860a;
  --gold-lt:    #f0a830;
  --gold-pale:  #fdf3e0;
  --cream:      #f7f4ef;
  --cream-dk:   #ede8e0;
  --text:       #1a1a2e;
  --text-muted: #666;
  --white:      #fff;
  --radius:     6px;
  --shadow:     0 4px 20px rgba(0,0,0,.1);
  --transition: 0.22s ease;
  --max-w:      1100px;
}

html { scroll-behavior: smooth; }

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text);
  background: var(--navy);
}

img { display: block; max-width: 100%; height: auto; }
a   { color: var(--gold); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--gold-lt); }
ul  { list-style: none; }

.container { width: 92%; max-width: var(--max-w); margin-inline: auto; }

/* ---- Shared typography ---- */
h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; color: var(--text); }
h3 { font-size: 1.05rem; font-weight: 600; }

.section-pre {
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--gold);
  margin-bottom: .4rem;
}

.section-title { text-align: center; margin-bottom: .5rem; }
.section-title.light { color: var(--white); }

.section-sub {
  text-align: center;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 2rem;
  font-size: .95rem;
}

/* ---- Buttons ---- */
.btn-primary {
  display: inline-block;
  padding: .65em 1.5em;
  background: var(--gold);
  color: var(--white);
  font-weight: 700;
  font-size: .9rem;
  border-radius: var(--radius);
  transition: background var(--transition), transform var(--transition);
}
.btn-primary:hover { background: var(--gold-lt); color: var(--white); transform: translateY(-1px); }

.btn-outline {
  display: inline-block;
  padding: .63em 1.4em;
  border: 2px solid var(--gold);
  color: var(--gold);
  font-weight: 700;
  font-size: .9rem;
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
}
.btn-outline:hover { background: var(--gold); color: var(--white); }

.full-width { width: 100%; text-align: center; }

/* =============================================
   NAV
   ============================================= */
#main-nav {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(15, 30, 46, 0.97);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(200,134,10,.25);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: .7rem 0;
  gap: 1rem;
}

.nav-brand {
  font-weight: 700;
  font-size: 1rem;
  color: var(--white);
  white-space: nowrap;
  flex-shrink: 0;
}
.nav-brand:hover { color: var(--gold-lt); }

#nav-list {
  display: flex;
  flex-wrap: wrap;
  gap: .1rem;
  align-items: center;
}

#nav-list li a {
  display: block;
  padding: .4em .75em;
  color: #c8d0da;
  font-size: .82rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .4px;
  border-radius: 3px;
  transition: color var(--transition), background var(--transition);
}
#nav-list li a:hover { color: var(--white); background: rgba(255,255,255,.07); }
#nav-list li a.active { color: var(--gold-lt); }

.nav-cta {
  background: var(--gold) !important;
  color: var(--white) !important;
  border-radius: var(--radius) !important;
  padding: .4em .9em !important;
}
.nav-cta:hover { background: var(--gold-lt) !important; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--gold-lt);
  font-size: 1.3rem;
  cursor: pointer;
  padding: .3rem;
}

/* =============================================
   HERO
   ============================================= */
#hero {
  background: linear-gradient(135deg, var(--navy-mid) 0%, #0a1520 100%);
  padding: 2rem 0 2rem;
  border-bottom: 3px solid var(--gold);
}

.hero-inner {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 1rem;
  align-items: center;
}

.hero-photo img {
  width: 220px;
  height: 220px;
  object-fit: cover;
  border-radius: 50%;
  border: 4px solid var(--gold);
  box-shadow: 0 0 40px rgba(200,134,10,.3);
  margin-inline: auto;
}

.hero-pre {
  font-size: .8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--gold);
  margin-bottom: .6rem;
}

.hero-text h1 {
  font-size: clamp(1rem, 4vw, 3rem);
  color: var(--white);
  line-height: 1.1;
  margin-bottom: .5rem;
}

.hero-affil {
  color: #8a9bb0;
  font-size: .95rem;
  margin-bottom: 1.2rem;
}

.hero-bio {
  color: #c8d0da;
  font-size: 1.05rem;
  max-width: 720px;
  margin-bottom: 1rem;
}
.hero-bio strong { color: var(--gold-lt); }

.hero-actions { display: flex; gap: 1rem; flex-wrap: wrap; }

/* =============================================
   STATS
   ============================================= */
#stats {
  background: var(--gold);
  padding: 1rem 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: .5rem;
  text-align: center;
}

.stat-card { padding: .1rem; }

.stat-number {
  display: block;
  font-size: clamp(1.6rem, 2.5vw, 2.4rem);
  font-weight: 800;
  color: var(--white);
  line-height: 1;
}

.stat-label {
  display: block;
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .5px;
  color: rgba(255,255,255,.85);
  margin-top: .25rem;
}

/* =============================================
   ABOUT
   ============================================= */
#about {
  background: var(--cream);
  padding: 3rem 0;
}

.about-grid {
  display: block;
  width: 100%;
}

.about-photo img {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.about-credentials {
  display: flex;
  gap: .5rem;
  margin-top: 1rem;
  flex-wrap: wrap;
  justify-content: center;
}

.about-credentials span {
  background: var(--navy);
  color: var(--gold-lt);
  padding: .25em .7em;
  border-radius: 3px;
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .5px;
}

.about-text h2 { margin: 0rem 2rem 2rem; margin-bottom: 1rem; }
.about-text p  { margin: 0rem 2rem 2rem; color: #444; margin-bottom: 1.05rem; }
.about-text strong { color: var(--navy); }


.about-roles {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  margin: 0.2rem 0;
}

.role-tag {
  display: flex;
  align-items: center;
  gap: .4rem;
  background: var(--cream-dk);
  border: 1px solid #d5cfc5;
  padding: .3em .8em;
  border-radius: 20px;
  font-size: .82rem;
  font-weight: 600;
  color: var(--navy);
}
.role-tag i { color: var(--gold); font-size: .85rem; }

/* =============================================
   BOOKS
   ============================================= */
#books {
  background: var(--cream-dk);
  padding: 2rem 0;
}

.book-filters {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  justify-content: center;
  margin-bottom: 2rem;
}

.filter-btn {
  padding: .4em 1.1em;
  border: 2px solid var(--gold);
  background: transparent;
  color: var(--gold);
  font-size: .82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .5px;
  border-radius: 20px;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}
.filter-btn:hover,
.filter-btn.active {
  background: var(--gold);
  color: var(--white);
}

.books-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 1.6rem;
}

.book-card {
  display: block;
  background: var(--white);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  color: var(--text);
}
.book-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 12px 32px rgba(0,0,0,.15);
  color: var(--text);
}
.book-card.hidden { display: none; }

.book-cover {
  position: relative;
  overflow: hidden;
  aspect-ratio: 2/3;
  background: #eee;
}

.book-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition);
}
.book-card:hover .book-cover img { transform: scale(1.04); }

.book-overlay {
  position: absolute;
  inset: 0;
  background: rgba(200,134,10,.88);
  color: var(--white);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  font-weight: 700;
  font-size: .9rem;
  opacity: 0;
  transition: opacity var(--transition);
}
.book-card:hover .book-overlay { opacity: 1; }

.book-info {
  padding: .8rem;
}
.book-info h3 {
  font-size: .88rem;
  line-height: 1.3;
  margin-bottom: .3rem;
  color: var(--text);
}
.book-cat {
  font-size: .72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .5px;
  color: var(--gold);
}

.books-note {
  margin-top: 2rem;
  text-align: center;
  font-size: .88rem;
  color: var(--text-muted);
  background: var(--gold-pale);
  border: 1px solid #e8d5a0;
  border-radius: var(--radius);
  padding: .8rem 1.2rem;
}
.books-note i { color: var(--gold); margin-right: .4rem; }

/* =============================================
   RESEARCH
   ============================================= */
#research {
  background: var(--white);
  padding: 5rem 0;
}

.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 1.4rem;
  margin-bottom: 3rem;
}

.research-card {
  text-align: center;
  padding: 2rem 1.4rem;
  border: 1px solid var(--cream-dk);
  border-top: 3px solid var(--gold);
  border-radius: var(--radius);
  background: var(--cream);
}

.research-icon {
  font-size: 1.8rem;
  color: var(--gold);
  margin-bottom: .8rem;
}

.research-card h3 {
  font-size: 2rem;
  font-weight: 800;
  color: var(--navy);
  margin-bottom: .4rem;
}

.research-card p { font-size: .88rem; color: var(--text-muted); }
.research-card strong { color: var(--navy); }

.research-areas { text-align: center; }
.research-areas h3 { font-size: 1rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text-muted); margin-bottom: 1rem; }

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  justify-content: center;
}

.tag-cloud span {
  background: var(--navy);
  color: var(--gold-lt);
  padding: .3em .9em;
  border-radius: 20px;
  font-size: .82rem;
  font-weight: 600;
}

/* =============================================
   PATENTS
   ============================================= */
#patents {
  background: var(--navy-lt);
  padding: 5rem 0;
}

#patents .section-pre,
#patents h2 { color: var(--white); }
#patents h2 { text-align: center; margin-bottom: 2.5rem; }

.patents-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 2fr;
  gap: 1.4rem;
  align-items: start;
}

.patent-card {
  background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.1);
  border-radius: var(--radius);
  padding: 2rem 1.6rem;
  text-align: center;
  color: var(--white);
}

.patent-card.featured { border-color: var(--gold); }
.patent-card.wide { text-align: left; }

.patent-count {
  display: block;
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--gold-lt);
  line-height: 1;
  margin-bottom: .4rem;
}

.patent-card h3 { font-size: 1rem; margin-bottom: .5rem; color: var(--white); }
.patent-card p  { font-size: .88rem; color: #8a9bb0; }
.patent-card p em { color: var(--gold-lt); font-style: italic; }
.patent-card p strong { color: var(--white); }

.patent-icon {
  font-size: 2rem;
  color: var(--gold);
  margin-bottom: 1rem;
  display: block;
}

/* =============================================
   AWARDS
   ============================================= */
#awards {
  background: var(--cream);
  padding: 5rem 0;
}

.awards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1.4rem;
}

.award-card {
  background: var(--white);
  border-radius: var(--radius);
  padding: 2rem 1.4rem;
  text-align: center;
  box-shadow: var(--shadow);
  border-bottom: 3px solid var(--gold);
  transition: transform var(--transition);
}
.award-card:hover { transform: translateY(-4px); }

/* Award photo strip */
.award-photos {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: .8rem;
  margin-top: 2.5rem;
}

.award-photo-item {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius);
  cursor: pointer;
  aspect-ratio: 4/3;
  background: #ddd;
}

.award-photo-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform .3s;
}

.award-photo-item:hover img { transform: scale(1.06); }

.award-photo-overlay {
  position: absolute;
  inset: 0;
  background: rgba(200,134,10,0);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  font-size: 1.4rem;
  opacity: 0;
  transition: background .22s, opacity .22s;
}
.award-photo-item:hover .award-photo-overlay { background: rgba(200,134,10,.6); opacity: 1; }

/* Award lightbox */
.award-lightbox {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.92);
  z-index: 9999;
  align-items: center;
  justify-content: center;
}
.award-lightbox.open { display: flex; }

.award-lightbox img {
  max-width: 90vw;
  max-height: 85vh;
  object-fit: contain;
  border-radius: 4px;
  box-shadow: 0 0 60px rgba(0,0,0,.8);
}

.award-lb-close {
  position: absolute;
  top: 1rem; right: 1.5rem;
  background: none; border: none;
  color: var(--white); font-size: 2.2rem;
  cursor: pointer; line-height: 1; opacity: .8;
}
.award-lb-close:hover { opacity: 1; }

.award-lb-nav {
  position: absolute;
  top: 50%; transform: translateY(-50%);
  background: rgba(200,134,10,.75);
  border: none; color: var(--white);
  font-size: 1.3rem; padding: .6rem .9rem;
  cursor: pointer; border-radius: 4px;
  transition: background .2s;
}
.award-lb-nav:hover { background: var(--gold); }
.award-lb-prev { left: 1rem; }
.award-lb-next { right: 1rem; }

@media (max-width: 600px) {
  .award-photos { grid-template-columns: repeat(2, 1fr); }
}

.award-card > i {
  font-size: 2rem;
  color: var(--gold);
  margin-bottom: .8rem;
}

.award-card h3 { font-size: .95rem; color: var(--navy); margin-bottom: .3rem; }
.award-card p  { font-size: .82rem; color: var(--text-muted); }

/* =============================================
   TALKS
   ============================================= */
#talks {
  background: var(--navy);
  padding: 5rem 0;
}

.talks-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.talks-text .section-pre { color: var(--gold); }
.talks-text h2 { color: var(--white); margin-bottom: 1rem; }
.talks-text p  { color: #8a9bb0; margin-bottom: .9rem; }
.talks-text strong { color: var(--white); }

.talks-stats {
  display: flex;
  flex-direction: column;
  gap: 1.4rem;
}

.talks-stat {
  background: rgba(255,255,255,.05);
  border-left: 3px solid var(--gold);
  padding: 1.2rem 1.6rem;
  border-radius: 0 var(--radius) var(--radius) 0;
}

.talks-stat span {
  display: block;
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--gold-lt);
  line-height: 1;
}

.talks-stat p { color: #8a9bb0; font-size: .88rem; margin-top: .2rem; }

/* =============================================
   CONTACT
   ============================================= */
#contact {
  background: var(--navy-mid);
  padding: 5rem 0;
}

#contact .section-pre { text-align: center; }

.contact-inner { }

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: 3rem;
  margin-top: 2rem;
}

.contact-item {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.6rem;
  align-items: flex-start;
}

.contact-item > i {
  font-size: 1.2rem;
  color: var(--gold);
  margin-top: .2rem;
  flex-shrink: 0;
  width: 1.4rem;
  text-align: center;
}

.contact-item strong { display: block; color: var(--white); font-size: .9rem; margin-bottom: .2rem; }
.contact-item p { color: #8a9bb0; font-size: .88rem; }

/* Form */
.contact-form { display: flex; flex-direction: column; gap: 1rem; }

.form-group { display: flex; flex-direction: column; gap: .3rem; }

.form-group label {
  font-size: .82rem;
  font-weight: 600;
  color: #8a9bb0;
  text-transform: uppercase;
  letter-spacing: .5px;
}

.form-group input,
.form-group select,
.form-group textarea {
  padding: .65em .9em;
  background: rgba(255,255,255,.07);
  border: 1px solid rgba(255,255,255,.15);
  border-radius: var(--radius);
  color: var(--white);
  font-size: .95rem;
  font-family: inherit;
  transition: border-color var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--gold);
}

.form-group select option { background: var(--navy); }
.form-group textarea { resize: vertical; }

.form-success {
  text-align: center;
  color: #6fcf97;
  font-size: .9rem;
  padding: .6rem;
  background: rgba(111,207,151,.1);
  border-radius: var(--radius);
}

/* =============================================
   FOOTER
   ============================================= */
#site-footer {
  background: #070e16;
  padding: 1.8rem 0;
  border-top: 1px solid rgba(200,134,10,.2);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-brand strong { color: var(--white); font-size: 1rem; }
.footer-brand p { color: #556; font-size: .8rem; }

.footer-nav { display: flex; flex-wrap: wrap; gap: .2rem; }
.footer-nav a {
  color: #556;
  font-size: .8rem;
  padding: .2em .6em;
  transition: color var(--transition);
}
.footer-nav a:hover { color: var(--gold-lt); }

.footer-copy { color: #445; font-size: .78rem; }

.footer-social { display: flex; gap: 1rem; align-items: center; flex-wrap: wrap; }
.footer-social a {
  color: #8a9bb0;
  font-size: .82rem;
  display: flex;
  align-items: center;
  gap: .35rem;
  transition: color var(--transition);
}
.footer-social a:hover { color: var(--gold-lt); }
.footer-social i { font-size: .9rem; }

/* =============================================
   RESPONSIVE
   ============================================= */
@media (max-width: 960px) {
  .stats-grid { grid-template-columns: repeat(3, 1fr); }
  .patents-grid { grid-template-columns: 1fr 1fr; }
  .patent-card.wide { grid-column: span 2; }
  .talks-inner { grid-template-columns: 1fr; gap: 2.5rem; }
}

@media (max-width: 768px) {
  /* Nav */
  .nav-toggle { display: block; }
  #nav-list {
    display: none;
    position: absolute;
    top: 100%;
    left: 0; right: 0;
    background: rgba(15,30,46,.98);
    flex-direction: column;
    align-items: stretch;
    padding: .5rem 1rem 1rem;
    border-top: 1px solid rgba(200,134,10,.2);
  }
  #nav-list.open { display: flex; }
  #nav-list li a { padding: .6em 1em; font-size: .9rem; }

  /* Hero */
  .hero-inner { grid-template-columns: 1fr; text-align: center; }
  .hero-photo img { width: 160px; height: 160px; }
  .hero-bio { margin-inline: auto; }
  .hero-actions { justify-content: center; }

  /* About */
  .about-photo { max-width: 200px; margin-inline: auto; }
  .about-roles { justify-content: center; }

  /* Contact */
  .contact-grid { grid-template-columns: 1fr; }

  /* Footer */
  .footer-inner { flex-direction: column; text-align: center; }
  .footer-nav { justify-content: center; }
}

@media (max-width: 520px) {
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .books-grid { grid-template-columns: repeat(2, 1fr); }
  .patents-grid { grid-template-columns: 1fr; }
  .patent-card.wide { grid-column: span 1; }
}