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

/* Root */
:root {
  --bg-color: #0f172a;
  --bg-color-alt: #16233b;
  --bg-light: #f8fafc;
  --card-bg: #ffffff;
  --card-soft: #f8fafc;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --secondary: #38bdf8;
  --text-dark: #1e293b;
  --text-light: #64748b;
  --border: #e2e8f0;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  --shadow-hover: 0 18px 35px rgba(15, 23, 42, 0.12);
  --radius: 16px;
  --radius-sm: 12px;
}

/* Smooth Scroll */
html {
  scroll-behavior: smooth;
}

body {
  font-family: Arial, sans-serif;
  line-height: 1.7;
  color: var(--text-dark);
  background: var(--bg-light);
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.15);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
}

.logo {
  color: #ffffff;
  text-decoration: none;
  font-size: 1rem;
  font-weight: 700;
  white-space: nowrap;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-links a {
  color: #e2e8f0;
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 600;
  transition: color 0.3s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--secondary);
}

/* Hero Section */
.hero-section {
  min-height: 92vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 110px 20px 70px;
  background: linear-gradient(135deg, #0f172a, #1b2b47, #0f172a);
  color: #ffffff;
  text-align: center;
}

.hero-content {
  max-width: 860px;
}

.home-photo {
  width: 165px;
  height: 165px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--secondary);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  margin-bottom: 24px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.home-photo:hover {
  transform: scale(1.04);
  box-shadow: 0 14px 36px rgba(0, 0, 0, 0.42);
}

.hero-tag {
  display: inline-block;
  margin-bottom: 18px;
  padding: 8px 16px;
  background: rgba(56, 189, 248, 0.14);
  border: 1px solid rgba(56, 189, 248, 0.35);
  border-radius: 999px;
  color: #dbeafe;
  font-weight: 600;
  font-size: 0.95rem;
}

.hero-content h1 {
  font-size: 3.4rem;
  line-height: 1.15;
  margin-bottom: 18px;
}

.hero-content h2 {
  font-size: 1.28rem;
  font-weight: 400;
  color: #cbd5e1;
  max-width: 780px;
  margin: 0 auto 28px;
}

.hero-highlights {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 28px;
}

.hero-highlights span {
  background: rgba(255, 255, 255, 0.08);
  padding: 10px 16px;
  border-radius: 999px;
  font-size: 0.95rem;
  color: #e2e8f0;
}

.hero-highlights i {
  margin-right: 8px;
  color: var(--secondary);
}

/* Buttons */
.cta-buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 14px;
  margin-bottom: 24px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 700;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
}

.primary-btn {
  background: var(--primary);
  color: #ffffff;
}

.primary-btn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
}

.secondary-btn {
  background: rgba(255, 255, 255, 0.1);
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.secondary-btn:hover {
  background: rgba(255, 255, 255, 0.16);
  transform: translateY(-2px);
}

.social-links {
  display: flex;
  justify-content: center;
  gap: 20px;
  flex-wrap: wrap;
  margin-top: 6px;
}

.social-links a {
  color: #dbeafe;
  text-decoration: none;
  font-weight: 600;
  transition: color 0.3s ease, transform 0.3s ease;
}

.social-links a:hover {
  color: var(--secondary);
  transform: translateY(-1px);
}

/* Sections */
.content-section {
  max-width: 1100px;
  margin: 36px auto;
  padding: 44px 30px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.content-section h2 {
  text-align: center;
  font-size: 2.1rem;
  margin-bottom: 24px;
  color: var(--text-dark);
}

.section-intro {
  max-width: 950px;
  margin: 0 auto;
}

.section-intro p {
  margin-bottom: 16px;
  color: var(--text-dark);
  font-size: 1.03rem;
}

/* Skills */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.skill-card {
  background: var(--card-soft);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 22px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 20px rgba(37, 99, 235, 0.08);
}

.skill-card h3 {
  margin-bottom: 10px;
  color: var(--primary);
  font-size: 1.1rem;
}

.skill-card p {
  color: var(--text-light);
}

/* Projects / Research cards */
.project-note {
  display: block;
  margin-top: 12px;
  color: var(--text-light);
  font-size: 0.85rem;
  line-height: 1.5;
}

.project-card .btn {
  margin-right: 10px;
  margin-bottom: 10px;
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 22px;
}

.project-card {
  background: var(--card-soft);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
  transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
}

.project-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
  border-color: #c7d2fe;
}

.project-top {
  margin-bottom: 14px;
}

.project-badge {
  display: inline-block;
  margin-bottom: 10px;
  padding: 6px 12px;
  background: rgba(37, 99, 235, 0.1);
  color: var(--primary);
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
}

.project-card h3 {
  font-size: 1.22rem;
  margin-bottom: 8px;
  line-height: 1.4;
  color: var(--text-dark);
}

.project-card p {
  color: var(--text-light);
  margin-bottom: 16px;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 18px;
}

.project-tags span {
  background: #e2e8f0;
  color: #334155;
  padding: 6px 10px;
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 600;
}

.project-btn {
  background: var(--primary);
  color: #ffffff;
}

.project-btn:hover {
  background: var(--primary-dark);
}

.section-button {
  text-align: center;
  margin-top: 28px;
}

/* Experience */
.timeline-item {
  padding: 22px 0;
  border-bottom: 1px solid var(--border);
}

.timeline-item:last-child {
  border-bottom: none;
}

.timeline-item h3 {
  margin-bottom: 6px;
  color: var(--text-dark);
  font-size: 1.2rem;
}

.timeline-meta {
  color: var(--primary);
  font-weight: 700;
  margin-bottom: 14px;
}

.detail-list {
  padding-left: 22px;
}

.detail-list li {
  margin-bottom: 10px;
  color: var(--text-dark);
}

/* Achievements */
.achievement-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.achievement-card {
  background: var(--card-soft);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  text-align: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.achievement-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 20px rgba(37, 99, 235, 0.08);
}

.achievement-card i {
  font-size: 1.8rem;
  color: var(--primary);
  margin-bottom: 14px;
}

.achievement-card h3 {
  margin-bottom: 10px;
}

.achievement-card p {
  color: var(--text-light);
}

/* Certifications + Publications */
.certifications-list,
.publication-list {
  list-style: none;
  padding: 0;
}

.certifications-list li,
.publication-list li {
  background: var(--card-soft);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 18px;
  margin-bottom: 14px;
  transition: box-shadow 0.3s ease, transform 0.3s ease;
}

.certifications-list li:hover,
.publication-list li:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 18px rgba(15, 23, 42, 0.06);
}

.certifications-list a,
.publication-list a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 700;
}

.certifications-list a:hover,
.publication-list a:hover {
  text-decoration: underline;
}

.certifications-list i {
  margin-right: 10px;
  color: var(--primary);
}

/* Contact */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}

.contact-card,
.contact-form-container {
  background: var(--card-soft);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
  min-height: 100%;
}

.contact-card h3 {
  margin-bottom: 14px;
  font-size: 1.3rem;
}

.contact-card p {
  color: var(--text-light);
  margin-bottom: 18px;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 14px;
  color: var(--text-dark);
}

.contact-item i {
  color: var(--primary);
  min-width: 18px;
  margin-top: 4px;
}

.contact-item a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 700;
}

.contact-item a:hover {
  text-decoration: underline;
}

form label {
  display: block;
  margin-bottom: 8px;
  font-weight: 700;
}

form input,
form textarea {
  display: block;
  width: 100%;
  margin-bottom: 18px;
  padding: 13px 14px;
  border: 1px solid #cbd5e1;
  border-radius: 10px;
  font-size: 1rem;
  background: #ffffff;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

form textarea {
  min-height: 140px;
  resize: vertical;
}

form input:focus,
form textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
}

.submit-btn {
  width: 100%;
  justify-content: center;
}

/* Footer */
footer {
  margin-top: 40px;
  padding: 24px 20px;
  background: #0f172a;
  color: #e2e8f0;
  text-align: center;
}

footer p:first-child {
  margin-bottom: 8px;
}

footer a {
  color: var(--secondary);
  text-decoration: none;
  font-weight: 700;
}

footer a:hover {
  text-decoration: underline;
}

/* Responsive */
@media (max-width: 1100px) {
  .nav-container {
    padding: 16px 18px;
  }

  .nav-links {
    gap: 14px;
  }
}

@media (max-width: 992px) {
  .skills-grid,
  .achievement-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .project-grid,
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .hero-section {
    min-height: auto;
    padding: 100px 20px 60px;
  }
}

@media (max-width: 768px) {
  .nav-container {
    flex-direction: column;
    align-items: flex-start;
  }

  .nav-links {
    gap: 12px;
  }

  .hero-content h1 {
    font-size: 2.45rem;
  }

  .hero-content h2 {
    font-size: 1.05rem;
  }

  .content-section {
    padding: 30px 18px;
    margin: 20px 12px;
  }

  .skills-grid,
  .achievement-grid {
    grid-template-columns: 1fr;
  }

  .home-photo {
    width: 140px;
    height: 140px;
  }

  .cta-buttons {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    justify-content: center;
    max-width: 320px;
  }

  .social-links {
    gap: 14px;
  }

  .hero-highlights {
    gap: 10px;
  }

  .hero-highlights span {
    font-size: 0.9rem;
  }
}

@media (max-width: 480px) {
  .hero-content h1 {
    font-size: 2rem;
  }

  .hero-tag {
    font-size: 0.82rem;
  }

  .content-section h2 {
    font-size: 1.7rem;
  }
}