:root{
  /* Light theme (default) - Two Color System */
  /* Primary: Deep Blue (#2563eb) - Professional, trustworthy, excellent for text */
  /* Accent: Warm Terracotta (#c2410c) - Complementary, adds warmth, good contrast */
  --bg: #ffffff;
  --surface: #f8fafc;
  --primary: #2563eb; /* Deep blue - optimal for typography */
  --accent: #c2410c; /* Warm terracotta - complementary to blue */
  --muted: #64748b; /* Neutral gray for secondary text */
  --text: #0f172a; /* Near black for maximum readability */
  --radius:14px;
  --container:1100px;
  --card-bg: #ffffff;
  --card-border: rgba(15,23,42,0.08);
  --shadow: rgba(15,23,42,0.08);
  --shadow-hover: rgba(15,23,42,0.12);
  --section-alt: #f8fafc; /* Alternate section background */
}

[data-theme="dark"]{
  /* Dark theme - Two Color System */
  --bg: #0f172a;
  --surface: #1e293b;
  --primary: #3b82f6; /* Lighter blue for dark backgrounds */
  --accent: #f97316; /* Brighter orange for dark backgrounds */
  --muted: #94a3b8;
  --text: #f1f5f9;
  --card-bg: rgba(30,41,59,0.5);
  --card-border: rgba(255,255,255,0.1);
  --shadow: rgba(0,0,0,0.3);
  --shadow-hover: rgba(0,0,0,0.5);
  --section-alt: #1e293b;
}
*{box-sizing:border-box}
html,body{height:100%}
.body-wrapper, body{
  margin:0;
  font-family:Inter,system-ui,-apple-system,Segoe UI,Roboto,"Helvetica Neue",Arial,sans-serif;
  background:var(--bg);
  color:var(--text);
  -webkit-font-smoothing:antialiased;
  line-height:1.6;
  transition:background 0.3s ease, color 0.3s ease;
}
.container{max-width:var(--container);margin:0 auto;padding:1rem 1.5rem}

/* General card look */
.card{
  background:var(--card-bg);
  border:1px solid var(--card-border);
  border-radius:var(--radius);
  padding:1rem;
  box-shadow:0 6px 18px var(--shadow);
  transition:background 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}
.container{max-width:var(--container);margin:0 auto;padding:1rem 1.5rem}

.site-header{
  background:rgba(255,255,255,0.9);
  backdrop-filter:blur(10px);
  position:sticky;
  top:0;
  z-index:100;
  padding:0.8rem 0;
  border-bottom:1px solid var(--card-border);
  transition:background 0.3s ease, border-color 0.3s ease;
}

[data-theme="dark"] .site-header{
  background:rgba(7,20,40,0.9);
}

.header-inner{display:flex;align-items:center;justify-content:space-between}
.header-actions{display:flex;align-items:center;gap:0.8rem}
.logo{color:var(--text);text-decoration:none;font-weight:700;font-size:1.1rem;letter-spacing:0.2px;transition:color 0.3s ease}

.theme-toggle{
  background:transparent;
  border:1px solid var(--card-border);
  border-radius:10px;
  padding:0;
  cursor:pointer;
  display:flex;
  align-items:center;
  justify-content:center;
  color:var(--text);
  transition:all 0.3s ease;
  width:40px;
  height:40px;
  position:relative;
}

.theme-toggle:hover{
  background:var(--surface);
  border-color:var(--primary);
  transform:scale(1.05);
}

.theme-icon{
  position:absolute;
  transition:opacity 0.3s ease, transform 0.3s ease;
}

.sun-icon{
  opacity:1;
  transform:rotate(0deg);
}

.moon-icon{
  opacity:0;
  transform:rotate(90deg);
}

[data-theme="dark"] .sun-icon{
  opacity:0;
  transform:rotate(90deg);
}

[data-theme="dark"] .moon-icon{
  opacity:1;
  transform:rotate(0deg);
}
.nav-toggle{display:none;background:var(--primary);color:white;padding:.4rem .7rem;border-radius:10px;border:none;box-shadow:0 4px 12px rgba(37,99,235,0.2);transition:all .3s ease;font-weight:600}
.nav-toggle:hover{background:var(--accent);box-shadow:0 6px 18px rgba(194,65,12,0.3)}
.primary-nav ul{list-style:none;margin:0;padding:0;display:flex;gap:0.6rem}
.primary-nav a{color:var(--muted);text-decoration:none;padding:.45rem .6rem;border-radius:999px;font-weight:500;transition:all .3s ease}
.primary-nav a:hover,.primary-nav a.active{color:white;background:var(--primary);box-shadow:0 4px 12px rgba(37,99,235,0.2)}

.hero{padding:4rem 0 3.2rem}
.hero-inner{display:grid;grid-template-columns:1fr 320px;gap:3rem;align-items:center}
.name{font-size:3rem;margin:.1rem 0;font-weight:700;color:var(--text);letter-spacing:-1px}
.tagline{color:var(--muted);margin:0 0 .8rem;font-size:1.1rem;font-weight:500}
.short-desc{color:var(--muted);margin-bottom:1.5rem;max-width:54ch;font-size:1.05rem;line-height:1.7}
.hero-actions{display:flex;flex-wrap:wrap;gap:.8rem;margin-bottom:1.5rem}
.hero-actions .btn{margin-right:0}
.profile-photo{width:320px;height:320px;object-fit:cover;border-radius:18px;border:4px solid var(--card-border);box-shadow:0 20px 50px var(--shadow);transform:translateY(0);animation:float 6s ease-in-out infinite;transition:border-color 0.3s ease, box-shadow 0.3s ease}

.social-links{display:flex;flex-wrap:wrap;gap:1rem;align-items:center;margin-top:1rem}
.social-link{display:flex;align-items:center;gap:.5rem;color:var(--muted);text-decoration:none;padding:.5rem 1rem;border-radius:10px;border:1px solid var(--card-border);background:var(--card-bg);transition:all .3s ease}
.social-link:hover{color:var(--text);background:var(--surface);border-color:var(--primary);transform:translateY(-2px)}
.social-link svg{flex-shrink:0}
.social-link span{font-weight:500}

@keyframes float{0%{transform:translateY(0)}50%{transform:translateY(-8px)}100%{transform:translateY(0)}}

.section{padding:3.5rem 0;position:relative;transition:background-color 0.3s ease}

/* Two-Color System: Alternating sections with primary blue and accent terracotta */
/* Light Theme - Using subtle tints of the two colors */
#home{background:var(--bg)}
#about{background:rgba(37,99,235,0.03)} /* Very subtle blue tint */
#skills{background:rgba(194,65,12,0.03)} /* Very subtle terracotta tint */
#experience{background:rgba(37,99,235,0.03)} /* Blue */
#projects{background:rgba(194,65,12,0.03)} /* Terracotta */
#travel{background:rgba(37,99,235,0.03)} /* Blue */
#publications{background:rgba(194,65,12,0.03)} /* Terracotta */
#services{background:rgba(37,99,235,0.03)} /* Blue */
#contact{background:var(--bg)}

/* Dark Theme - Using subtle tints of the two colors */
[data-theme="dark"] #home{background:var(--bg)}
[data-theme="dark"] #about{background:rgba(59,130,246,0.05)} /* Subtle blue tint */
[data-theme="dark"] #skills{background:rgba(249,115,22,0.05)} /* Subtle orange tint */
[data-theme="dark"] #experience{background:rgba(59,130,246,0.05)} /* Blue */
[data-theme="dark"] #projects{background:rgba(249,115,22,0.05)} /* Orange */
[data-theme="dark"] #travel{background:rgba(59,130,246,0.05)} /* Blue */
[data-theme="dark"] #publications{background:rgba(249,115,22,0.05)} /* Orange */
[data-theme="dark"] #services{background:rgba(59,130,246,0.05)} /* Blue */
[data-theme="dark"] #contact{background:var(--bg)}
.section-title{font-size:2.2rem;margin:0 0 2rem;font-weight:700;color:var(--text);position:relative;padding-bottom:.5rem;letter-spacing:-0.5px}
.section-title::after{content:'';position:absolute;bottom:0;left:0;width:60px;height:3px;background:var(--primary);border-radius:2px}

/* Alternate section titles with accent color */
#skills .section-title::after,
#projects .section-title::after,
#publications .section-title::after{background:var(--accent)}
.section .card{padding:1.2rem}

/* About Section Redesign */
.about-intro{margin-bottom:3rem;text-align:center}
.about-lead{font-size:1.25rem;color:var(--text);line-height:1.8;max-width:800px;margin:0 auto;font-weight:500}

.about-stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:1.5rem;margin-bottom:3rem}
.stat-card{background:var(--card-bg);padding:2rem 1.5rem;border-radius:12px;border:1px solid var(--card-border);text-align:center;transition:all .3s ease}
.stat-card:hover{transform:translateY(-4px);border-color:var(--primary);box-shadow:0 8px 24px var(--shadow-hover)}
.stat-number{font-size:2.5rem;font-weight:700;color:var(--primary);margin-bottom:0.5rem;line-height:1}
.stat-label{color:var(--muted);font-size:0.95rem;font-weight:500}

.about-main{display:flex;flex-direction:column;gap:3rem}
.about-content-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:1.5rem}
.about-card{background:var(--card-bg);padding:2rem;border-radius:12px;border:1px solid var(--card-border);transition:all .3s ease;position:relative}
.about-card:hover{transform:translateY(-4px);border-color:var(--primary);box-shadow:0 8px 24px var(--shadow-hover)}
.about-card-icon{width:48px;height:48px;background:rgba(37,99,235,0.1);border-radius:10px;display:flex;align-items:center;justify-content:center;margin-bottom:1rem;color:var(--primary)}
.about-card h3{color:var(--text);font-size:1.3rem;margin:0 0 1rem;font-weight:600}
.about-card p{color:var(--muted);margin-bottom:0.8rem;line-height:1.7;font-size:0.95rem}
.about-card p:last-child{margin-bottom:0}
.about-card strong{color:var(--text);font-weight:600}

.about-interests{margin-top:1rem}
.interests-title{color:var(--text);font-size:1.5rem;margin:0 0 1.5rem;font-weight:600;text-align:center}
.interests-grid{display:flex;flex-wrap:wrap;gap:1rem;justify-content:center}
.interest-tag{background:var(--card-bg);padding:0.8rem 1.2rem;border-radius:8px;border:1px solid var(--card-border);color:var(--text);font-size:0.95rem;display:flex;align-items:center;gap:0.6rem;transition:all .3s ease;font-weight:500}
.interest-tag:hover{background:var(--surface);border-color:var(--primary);transform:translateY(-2px);box-shadow:0 4px 12px var(--shadow)}
.interest-tag svg{flex-shrink:0;color:var(--primary)}

.about-mission{margin-top:2rem}
.mission-card{background:var(--card-bg);padding:2rem;border-radius:12px;border:2px solid var(--primary);display:flex;gap:1.5rem;align-items:flex-start;transition:all .3s ease}
.mission-card:hover{box-shadow:0 8px 24px rgba(37,99,235,0.15);transform:translateY(-2px)}
.mission-icon{width:48px;height:48px;background:rgba(37,99,235,0.1);border-radius:10px;display:flex;align-items:center;justify-content:center;flex-shrink:0;color:var(--primary)}
.mission-content h3{color:var(--text);font-size:1.3rem;margin:0 0 0.8rem;font-weight:600}
.mission-content p{color:var(--muted);margin:0;line-height:1.7;font-size:1.05rem}

.skills-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:1.2rem}
.skill-card{background:var(--card-bg);padding:1.5rem;border-radius:12px;border:1px solid var(--card-border);transition:all .3s ease}
.skill-card:hover{transform:translateY(-4px);border-color:var(--primary);box-shadow:0 8px 24px var(--shadow-hover)}
.skill-card h3{color:var(--text);font-size:1.1rem;margin:0 0 1rem;font-weight:600}
.skill-card ul{list-style:none;margin:0;padding:0}
.skill-card li{color:var(--muted);padding:.4rem 0;position:relative;padding-left:1.2rem}
.skill-card li::before{content:'▹';position:absolute;left:0;color:var(--primary)}

/* Reveal animation */
.reveal{opacity:0;transform:translateY(10px);transition:opacity .7s cubic-bezier(.2,.9,.2,1),transform .7s cubic-bezier(.2,.9,.2,1)}
.reveal.visible{opacity:1;transform:none}

.timeline{display:flex;flex-direction:column;gap:1.5rem;position:relative;padding-left:2rem}
.timeline::before{content:'';position:absolute;left:0;top:0;bottom:0;width:2px;background:var(--primary);border-radius:2px;opacity:0.3}
.timeline-item{background:var(--card-bg);padding:1.5rem;border-radius:12px;border:1px solid var(--card-border);position:relative;transition:all .3s ease}
.timeline-item::before{content:'';position:absolute;left:-2.5rem;top:1.8rem;width:12px;height:12px;background:var(--primary);border-radius:50%;border:3px solid var(--bg);box-shadow:0 0 0 2px var(--primary)}
.timeline-item:hover{transform:translateX(4px);border-color:var(--primary)}
.timeline-header{display:flex;justify-content:space-between;align-items:flex-start;flex-wrap:wrap;gap:.5rem;margin-bottom:.5rem}
.timeline-item h3{margin:0;color:var(--text);font-size:1.2rem;font-weight:600}
.organization{color:var(--primary);font-weight:500;margin-bottom:.5rem;display:block}
.meta{display:block;color:var(--muted);font-size:.9rem;font-weight:500;white-space:nowrap}
.timeline-item p{color:var(--muted);margin:0;line-height:1.7}

.projects-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:1.5rem}
.project-card{background:var(--card-bg);padding:1.5rem;border-radius:12px;border:1px solid var(--card-border);transition:all .3s ease;display:flex;flex-direction:column}
.project-card:hover{transform:translateY(-6px);box-shadow:0 18px 40px var(--shadow-hover);border-color:var(--primary)}
.project-card h3{color:var(--text);font-size:1.3rem;margin:0 0 .8rem;font-weight:600}
.project-card > p{color:var(--muted);margin-bottom:1rem;line-height:1.7;flex-grow:1}
.project-tech{display:flex;flex-wrap:wrap;gap:.5rem;margin-bottom:1rem}
.tech-tag{background:rgba(79,143,230,0.15);color:var(--primary);padding:.3rem .7rem;border-radius:6px;font-size:.85rem;font-weight:500;border:1px solid rgba(79,143,230,0.3)}
.project-links{margin-top:auto}
.project-link{display:inline-flex;align-items:center;gap:.5rem;color:var(--primary);text-decoration:none;font-weight:500;transition:all .3s ease}
.project-link:hover{color:var(--accent);gap:.7rem}
.project-link svg{flex-shrink:0}

.publications-content{display:flex;flex-direction:column;gap:2.5rem}
.publication-category h3{color:var(--text);font-size:1.3rem;margin:0 0 1rem;font-weight:600}
.publications-list{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:1.5rem}
.publications-list li{background:var(--card-bg);padding:1.2rem;border-radius:10px;border-left:3px solid var(--primary);border:1px solid var(--card-border);border-left:3px solid var(--primary);transition:all .3s ease}
.publications-list li:hover{transform:translateX(4px);border-left-color:var(--accent)}
.publications-list li strong{color:var(--text);display:block;margin-bottom:.3rem;font-size:1.05rem}
.pub-meta{color:var(--muted);font-size:.9rem;font-style:italic}
.pub-desc{color:var(--muted);margin-top:.5rem;line-height:1.6;font-size:.95rem}

.travel-intro{color:var(--muted);margin-bottom:2.5rem;font-size:1.05rem;max-width:700px;text-align:center;margin-left:auto;margin-right:auto}
.travel-gallery{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:1.5rem}
.travel-item{position:relative;border-radius:12px;overflow:hidden;cursor:pointer;transition:all .3s ease;aspect-ratio:4/3}
.travel-item:hover{transform:translateY(-8px);box-shadow:0 20px 50px var(--shadow-hover)}
.travel-image-wrapper{position:relative;width:100%;height:100%;overflow:hidden;border-radius:12px;border:1px solid var(--card-border)}
.travel-image{width:100%;height:100%;object-fit:cover;transition:transform .5s ease;display:block}
.travel-item:hover .travel-image{transform:scale(1.1)}
.travel-overlay{position:absolute;bottom:0;left:0;right:0;background:linear-gradient(to top,rgba(0,0,0,0.8) 0%,rgba(0,0,0,0.4) 50%,transparent 100%);padding:1.5rem;transform:translateY(20px);opacity:0;transition:all .3s ease}
.travel-item:hover .travel-overlay{transform:translateY(0);opacity:1}
.travel-info{color:white}
.travel-info h3{color:white;font-size:1.2rem;margin:0 0 .3rem;font-weight:600}
.travel-location{color:rgba(255,255,255,0.9);font-size:.95rem;margin:0 0 .2rem}
.travel-date{color:rgba(255,255,255,0.7);font-size:.85rem;margin:0}

.travel-lightbox{
  display:none;
  position:fixed;
  top:0;
  left:0;
  width:100%;
  height:100%;
  background:rgba(0,0,0,0.95);
  z-index:1000;
  align-items:center;
  justify-content:center;
  padding:2rem;
  backdrop-filter:blur(10px);
  opacity:0;
  transition:opacity .3s ease;
}

.travel-lightbox.active{
  display:flex;
  opacity:1;
}

.lightbox-close{
  position:absolute;
  top:2rem;
  right:2rem;
  background:transparent;
  border:none;
  color:white;
  font-size:3rem;
  cursor:pointer;
  width:50px;
  height:50px;
  display:flex;
  align-items:center;
  justify-content:center;
  border-radius:50%;
  transition:all .3s ease;
  z-index:1001;
}

.lightbox-close:hover{
  background:rgba(255,255,255,0.1);
  transform:rotate(90deg);
}

.lightbox-content{
  max-width:90vw;
  max-height:90vh;
  position:relative;
  display:flex;
  flex-direction:column;
  align-items:center;
  gap:1.5rem;
}

.lightbox-img{
  max-width:100%;
  max-height:75vh;
  object-fit:contain;
  border-radius:12px;
  box-shadow:0 20px 60px rgba(0,0,0,0.5);
}

.lightbox-info{
  text-align:center;
  color:white;
}

.lightbox-info h3{
  color:white;
  font-size:1.5rem;
  margin:0 0 .5rem;
  font-weight:600;
}

.lightbox-info p{
  color:rgba(255,255,255,0.8);
  margin:.3rem 0;
  font-size:1rem;
}

.services-intro{color:var(--muted);margin-bottom:2rem;font-size:1.05rem;max-width:700px}
.services-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:1.5rem}
.service-card{background:var(--card-bg);padding:1.5rem;border-radius:12px;border:1px solid var(--card-border);transition:all .3s ease}
.service-card:hover{transform:translateY(-4px);border-color:var(--primary);box-shadow:0 8px 24px var(--shadow-hover)}
.service-card h3{color:var(--text);font-size:1.2rem;margin:0 0 .8rem;font-weight:600}
.service-card p{color:var(--muted);margin:0;line-height:1.7}

.contact-wrapper{display:grid;grid-template-columns:1fr 1.5fr;gap:3rem;align-items:start}
.contact-info p{color:var(--muted);margin-bottom:1.5rem;font-size:1.05rem;line-height:1.7}
.contact-details{display:flex;flex-direction:column;gap:1rem}
.contact-item{background:var(--card-bg);padding:1rem;border-radius:10px;border:1px solid var(--card-border)}
.contact-item strong{color:var(--text);display:block;margin-bottom:.3rem;font-weight:600}
.contact-item a{color:var(--primary);text-decoration:none;transition:color .3s ease;display:inline-block;margin-top:0.3rem}
.contact-item a:hover{color:var(--accent)}
.contact-item a:first-of-type{margin-top:0}
.contact-item span{color:var(--muted)}

.contact-form{display:grid;gap:1rem;max-width:100%}
.contact-form label{display:flex;flex-direction:column;gap:.5rem}
.contact-form label span{color:var(--text);font-weight:500;font-size:.95rem}
.contact-form input,.contact-form textarea{width:100%;padding:.9rem;border-radius:10px;border:1px solid var(--card-border);background:var(--card-bg);color:var(--text);font-family:inherit;font-size:1rem;transition:all .3s ease}
.contact-form input:focus,.contact-form textarea:focus{outline:none;border-color:var(--primary);background:var(--surface);box-shadow:0 0 0 3px rgba(37,99,235,0.1)}
.contact-form input::placeholder,.contact-form textarea::placeholder{color:var(--muted);opacity:.6}

.btn{display:inline-block;padding:.75rem 1.5rem;border-radius:10px;text-decoration:none;border:1px solid rgba(255,255,255,0.06);font-weight:500;font-size:1rem;cursor:pointer;transition:all .3s ease;text-align:center}

.btn.primary{background:var(--primary);color:white;border-color:transparent;box-shadow:0 4px 15px rgba(37,99,235,0.25);font-weight:600;letter-spacing:0.3px;}
.btn.primary:hover{background:var(--accent);transform:translateY(-3px);box-shadow:0 6px 20px rgba(194,65,12,0.3)}
.btn.ghost{background:transparent;color:var(--text);border:1px solid var(--card-border)}
.btn.ghost:hover{transform:translateY(-3px);background:var(--surface);border-color:var(--primary)}

.site-footer{padding:1.2rem 0;color:var(--muted);border-top:1px solid var(--card-border);transition:border-color 0.3s ease}

/* Responsive */
@media (max-width:900px){
  .hero{padding:2.5rem 0}
  .hero-inner{grid-template-columns:1fr;grid-template-rows:auto auto;gap:2rem;text-align:center}
  .hero-content{display:flex;flex-direction:column;align-items:center}
  .name{font-size:2.2rem}
  .profile-photo{width:220px;height:220px;margin:0 auto;display:block}
  .primary-nav{position:fixed;right:1rem;top:64px;background:var(--card-bg);padding:1rem;border-radius:12px;display:none;box-shadow:0 10px 40px var(--shadow-hover);backdrop-filter:blur(10px);min-width:200px;border:1px solid var(--card-border)}
  .primary-nav.open{display:block}
  .nav-toggle{display:inline-block}
  .primary-nav ul{flex-direction:column;gap:.3rem}
  .primary-nav a{display:block;padding:.6rem .8rem}
  .section{padding:2.5rem 0}
  .section-title{font-size:1.8rem}
  .skills-grid{grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}
  .projects-grid{grid-template-columns:1fr}
  .timeline{padding-left:1.5rem}
  .timeline::before{left:-.5rem}
  .timeline-item::before{left:-1.75rem}
  .contact-wrapper{grid-template-columns:1fr;gap:2rem}
  .services-grid{grid-template-columns:1fr}
  .travel-gallery{grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:1rem}
  .social-links{justify-content:center}
  .about-stats{grid-template-columns:1fr;gap:1rem}
  .about-content-grid{grid-template-columns:1fr}
  .interests-grid{justify-content:flex-start}
}

@media (prefers-reduced-motion: no-preference){
  html{scroll-behavior:smooth}
}

@media (max-width:600px){
  .container{padding:1rem}
  .name{font-size:1.8rem}
  .section-title{font-size:1.5rem}
  .hero-actions{flex-direction:column;width:100%}
  .hero-actions .btn{width:100%}
  .social-links{flex-direction:column;width:100%}
  .social-link{width:100%;justify-content:center}
  .travel-gallery{grid-template-columns:1fr;gap:1rem}
  .travel-overlay{opacity:1;transform:translateY(0);background:linear-gradient(to top,rgba(0,0,0,0.7) 0%,rgba(0,0,0,0.3) 50%,transparent 100%)}
}