:root {
  /* Enterprise Theme Colors (Delta / Tech Corporate) */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-dark: #0f172a;
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --accent: #2563eb; /* Corporate Blue */
  --accent-hover: #1d4ed8;
  --accent-light: rgba(37, 99, 235, 0.1);
  --border-color: #e2e8f0;
  
  /* Typography */
  --font-main: 'Inter', sans-serif;
  --font-mono: 'Roboto Mono', monospace;
  
  --section-padding: 5rem 0;
}

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

html {
  scroll-behavior: smooth;
  overflow-x: hidden;
}

body {
  font-family: var(--font-main);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
}

.bg-light { background-color: var(--bg-secondary); }

.section-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 5%;
}

.section { padding: var(--section-padding); }

/* Typography Helpers */
.text-center { text-align: center; }
.text-accent { color: var(--accent); }
.text-secondary { color: var(--text-secondary); }
.text-sm { font-size: 0.9rem; }
.fw-600 { font-weight: 600; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 2rem; }

/* Navigation */
.enterprise-nav {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  padding: 1rem 5%;
  transition: all 0.3s ease;
}

.enterprise-nav.scrolled {
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  padding: 0.8rem 5%;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.logo span {
  color: var(--accent);
  font-weight: 500;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  margin-left: 2rem;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.3s ease;
}

.nav-links a:hover { color: var(--accent); }

.menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-primary);
  cursor: pointer;
}

/* Mobile Menu */
.mobile-menu {
  position: fixed;
  top: 0;
  right: -100%;
  width: 70vw;
  height: 100vh;
  background: var(--bg-secondary);
  box-shadow: -5px 0 15px rgba(0,0,0,0.1);
  z-index: 999;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  transition: right 0.3s ease;
}

.mobile-menu.active { right: 0; }
.mobile-link { font-size: 1.2rem; font-weight: 600; color: var(--text-primary); text-decoration: none; }

/* Hero Section */
.hero-section {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 5rem;
  background-color: var(--bg-dark);
  color: #fff;
  position: relative;
  overflow: hidden;
}

.pattern-bg::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background-image: radial-gradient(#334155 1px, transparent 1px);
  background-size: 30px 30px;
  opacity: 0.2;
  z-index: 0;
}

.hero-content {
  flex: 1;
  max-width: 600px;
  position: relative;
  z-index: 1;
  margin-left: max(5%, calc((100vw - 1200px) / 2));
}

.greeting {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent);
  letter-spacing: 2px;
  margin-bottom: 1rem;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 0.5rem;
}

.hero-subtitle {
  font-size: 1.5rem;
  color: #94a3b8;
  font-weight: 400;
  min-height: 36px;
  margin-bottom: 1rem;
}

.cursor { display: inline-block; width: 2px; background-color: var(--accent); animation: blink 1s infinite; }
@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: 0; } }

.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.corp-badge {
  background: rgba(37, 99, 235, 0.2);
  border: 1px solid rgba(37, 99, 235, 0.4);
  color: #93c5fd;
  padding: 0.3rem 0.8rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-family: var(--font-mono);
}

.hero-description {
  color: #cbd5e1;
  font-size: 1.05rem;
  margin-bottom: 2rem;
  max-width: 550px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: 4px;
  text-decoration: none;
  transition: all 0.2s ease;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background-color: var(--accent);
  color: #fff;
}
.btn-primary:hover { background-color: var(--accent-hover); }

.btn-secondary {
  background-color: transparent;
  color: #fff;
  border: 1px solid #475569;
  margin-left: 1rem;
}
.btn-secondary:hover { background-color: rgba(255,255,255,0.05); }

.hero-graphic {
  flex: 1;
  display: flex;
  justify-content: flex-end;
  padding-right: max(5%, calc((100vw - 1200px) / 2));
  position: relative;
  z-index: 1;
}

/* Sections Structure */
.section-header { margin-bottom: 3rem; }
.section-title {
  font-size: 2.2rem;
  color: var(--text-primary);
  font-weight: 700;
}
.title-underline {
  width: 60px;
  height: 4px;
  background-color: var(--accent);
  margin-top: 0.5rem;
}
.section-subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Corporate Card Style (Replaces Glassmorphism) */
.corp-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 2rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.corp-card:hover {
  box-shadow: 0 10px 25px -5px rgba(0,0,0,0.1);
  transform: translateY(-2px);
}

/* Profiles & Resume */
.resume-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}

.resume-cat-title {
  font-size: 1.3rem;
  margin-bottom: 1.5rem;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.resume-cat-title i { color: var(--accent); }

.skill-group { padding: 1rem 0; }
.skill-group:first-child { padding-top: 0; }
.skill-group:last-child { padding-bottom: 0; }
.border-top { border-top: 1px solid var(--border-color); }

.skill-group h4 { font-size: 0.95rem; color: var(--text-primary); margin-bottom: 0.3rem; }
.skill-group p { font-size: 0.95rem; color: var(--text-secondary); }

/* Projects Grid */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.project-card {
  padding: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.project-content { padding: 1.5rem; }
.course-code {
  font-size: 0.8rem;
  font-family: var(--font-mono);
  color: var(--accent);
  font-weight: 600;
  display: block;
  margin-bottom: 0.5rem;
}

.project-content h3 { font-size: 1.2rem; margin-bottom: 0.5rem; }
.project-content p { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: 1.5rem; }

.tech-stack {
  margin-top: auto;
  font-size: 0.8rem;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
  font-family: var(--font-mono);
}

/* Enterprise List (Works & Research) */
.enterprise-list {
  list-style: none;
}

.enterprise-list li {
  display: flex;
  gap: 1.5rem;
  padding: 1.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  margin-bottom: 1rem;
  border-radius: 6px;
  transition: border-color 0.2s ease;
}

.enterprise-list li:hover {
  border-color: var(--accent);
}

.enterprise-list i {
  font-size: 1.5rem;
  margin-top: 0.2rem;
}

.enterprise-list strong {
  display: block;
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
}

.enterprise-list p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin: 0;
}

/* Activities Grid */
.activities-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.activity-item { padding: 2rem; }
.activity-icon {
  font-size: 2rem;
  color: var(--accent);
  margin-bottom: 1rem;
}
.activity-item h4 { font-size: 1.2rem; margin-bottom: 1rem; }
.simple-list {
  list-style-type: disc;
  padding-left: 1.2rem;
  color: var(--text-secondary);
}
.simple-list li {
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

/* Contact */
.contact-box {
  max-width: 800px;
  margin: 0 auto;
}

.contact-info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
}

.info-card {
  text-align: center;
  padding: 1.5rem;
  background: var(--bg-primary);
  border-radius: 6px;
  border: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.info-card i { font-size: 1.5rem; color: var(--accent); margin-bottom: 1rem; display: block; }

.info-card span { 
    font-weight: 500; 
    font-size: 0.95rem;
    word-break: break-all;
    display: inline-block;
    max-width: 100%;
}

/* Placeholder & Lightbox */
.image-placeholder {
  background: #cbd5e1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  color: #475569;
  cursor: pointer;
  transition: background 0.2s ease;
}

.image-placeholder:hover { background: #94a3b8; color: #1e293b; }
.image-placeholder i { font-size: 2rem; margin-bottom: 0.5rem; }
.image-placeholder span { font-size: 0.85rem; font-weight: 500; }

.profile-placeholder {
  width: 320px;
  height: 320px;
  border-radius: 50%;
  border: 4px solid rgba(255,255,255,0.1);
  background: rgba(255,255,255,0.05);
  color: #94a3b8;
}
.profile-placeholder:hover { background: rgba(255,255,255,0.1); }
.profile-img {
  width: 320px;
  height: 320px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--accent);
  box-shadow: 0 4px 15px rgba(0,0,0,0.2);
  cursor: pointer;
}

/* Expandable Cards styling */
.expandable-card .expanded-content {
    display: none;
    animation: fadeReveal 0.4s ease forwards;
}
.expandable-card.is-expanded .expanded-content {
    display: block;
}

@keyframes fadeReveal {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.btn-text {
    background: none;
    border: none;
    color: var(--accent);
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 0;
    font-family: var(--font-main);
    font-size: 0.95rem;
}
.btn-text:hover { color: var(--accent-hover); }
.btn-text i { transition: transform 0.3s ease; }
.expandable-card.is-expanded .btn-text i { transform: rotate(180deg); }

.sub-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    gap: 1.2rem;
    border-top: 1px solid var(--border-color);
    margin-top: 1rem;
    padding-top: 1.5rem;
}
.sub-card {
    text-align: center;
}
.mini-img {
    width: 100%;
    height: 100px;
    border-radius: 6px;
    object-fit: cover;
}
.text-xs { font-size: 0.75rem; }

.project-img {
  width: 100%;
  height: 180px;
  border-radius: 8px 8px 0 0;
  object-fit: cover;
}
.real-img {
  cursor: pointer;
  transition: transform 0.2s ease;
}
.real-img:hover {
  transform: scale(1.02);
}

/* Lightbox Modal */
.lightbox {
  display: none;
  position: fixed;
  z-index: 9999;
  padding-top: 60px;
  left: 0; top: 0;
  width: 100%; height: 100%;
  background-color: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(10px);
}
.lightbox.active { display: block; }

.lightbox-content {
  margin: auto;
  display: block;
  max-width: 90%;
  max-height: 80vh;
  box-shadow: 0 0 20px rgba(0,0,0,0.5);
  background: #cbd5e1; /* Dummy background for placeholder image */
  border-radius: 8px;
}

#lightbox-caption {
  margin: auto;
  display: block;
  width: 80%;
  text-align: center;
  color: #f8fafc;
  padding: 15px 0;
  font-size: 1.2rem;
}

.lightbox-close {
  position: absolute;
  top: 15px;
  right: 35px;
  color: #f8fafc;
  font-size: 40px;
  font-weight: bold;
  cursor: pointer;
}
.lightbox-close:hover { color: var(--accent); }

/* Animations */
.fade-up { opacity: 0; transform: translateY(20px); transition: opacity 0.6s ease, transform 0.6s ease; }
.fade-up.visible { opacity: 1; transform: translateY(0); }
.slide-up { transform: translateY(15px); opacity: 0; }
.fade-in { animation: slideUpFade 0.7s forwards ease-out; }
.delay-1 { animation-delay: 0.1s; transition-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; transition-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; transition-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; transition-delay: 0.4s; }
.delay-5 { animation-delay: 0.5s; transition-delay: 0.5s; }
@keyframes slideUpFade { to { transform: translateY(0); opacity: 1; } }

/* Footer */
footer {
  text-align: center;
  padding: 2rem;
  background: var(--bg-dark);
  color: #94a3b8;
  font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 900px) {
  .hero-section { flex-direction: column; text-align: center; padding-top: 8rem; padding-bottom: 4rem; }
  .hero-content { margin-left: 0; max-width: 100%; display: flex; flex-direction: column; align-items: center; }
  .hero-graphic { padding-right: 0; margin-top: 3rem; justify-content: center; }
  .resume-grid { grid-template-columns: 1fr; }
  .hero-title { font-size: 2.8rem; }
}

@media (max-width: 768px) {
  .nav-links { display: none; }
  .menu-btn { display: block; }
  .enterprise-list li { flex-direction: column; gap: 0.5rem; }
}