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

/* Custom Properties */
:root {
  --primary-bg: #1e3a8a; /* Deep blue */
  --secondary-bg: #1f2937; /* Dark slate */
  --accent-color: #2dd4bf; /* Vibrant teal */
  --hover-accent: #14b8a6;
  --text-color: #f3f4f6;
  --shadow-color: rgba(0, 0, 0, 0.3);
  --light-bg: #f9fafb;
  --light-secondary-bg: #e5e7eb;
  --light-text-color: #111827;
  --progress-bg: #4b5563;
  --progress-fill: var(--accent-color);
  --transition: all 0.3s ease;
}

/* Light Mode */
.light-mode {
  --primary-bg: var(--light-bg);
  --secondary-bg: var(--light-secondary-bg);
  --text-color: var(--light-text-color);
  --shadow-color: rgba(0, 0, 0, 0.15);
  --progress-bg: #d1d5db;
}

/* General Styles */
body {
  font-family: 'Roboto', sans-serif;
  background: var(--primary-bg);
  color: var(--text-color);
  scroll-behavior: smooth;
  line-height: 1.6;
}

/* Navbar */
header {
  background: rgba(30, 58, 138, 0.95);
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--secondary-bg);
}

.navbar-brand.logo {
  color: var(--accent-color);
  font-size: 1.6rem;
  font-weight: 700;
}

.navbar-nav .nav-link {
  color: var(--text-color);
  font-size: 1.1rem;
  padding: 0.5rem 1rem;
  transition: var(--transition);
}

.navbar-nav .nav-link:hover,
.navbar-nav .nav-link.active {
  color: var(--accent-color);
}

.theme-toggle {
  background: transparent;
  border: 1px solid var(--accent-color);
  color: var(--accent-color);
  padding: 0.5rem;
  border-radius: 50%;
  font-size: 1rem;
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 5rem 2rem;
  background: linear-gradient(135deg, #1e40af, var(--primary-bg));
}

.hero img {
  width: 160px;
  border-radius: 50%;
  border: 4px solid var(--accent-color);
  margin-bottom: 1.5rem;
  transition: var(--transition);
}

.hero img:hover {
  transform: scale(1.1);
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--accent-color);
}

.hero h1 span {
  color: var(--accent-color);
}

.hero p {
  font-size: 1.2rem;
  color: #d1d5db;
  margin-bottom: 1.5rem;
}

.hero .btn {
  padding: 0.8rem 2rem;
  background: var(--accent-color);
  color: var(--primary-bg);
  font-weight: 500;
  border-radius: 30px;
  text-decoration: none;
  box-shadow: 0 0 10px var(--accent-color);
  transition: var(--transition);
}

.hero .btn:hover {
  background: var(--hover-accent);
  transform: translateY(-3px);
  box-shadow: 0 0 15px var(--accent-color);
}

/* Section */
.section {
  padding: 4rem 1.5rem;
  max-width: 1200px;
  margin: auto;
}

.section h2 {
  text-align: center;
  margin-bottom: 2.5rem;
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--accent-color);
}

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

/* Card */
.card {
  background: var(--secondary-bg);
  color: var(--text-color);
  border: none;
  box-shadow: 0 4px 12px var(--shadow-color);
  border-radius: 12px;
  padding: 1.5rem;
  transition: var(--transition);
  opacity: 0;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 16px var(--shadow-color);
}

.card.visible {
  opacity: 1;
}

.center {
  text-align: center;
}

/* Skills Grid */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
}

.skills-grid ul {
  list-style: none;
  padding: 0;
}

.skills-grid li {
  display: flex;
  align-items: center;
  margin-bottom: 0.8rem;
  font-size: 0.95rem;
}

.progress-bar {
  width: 100px;
  height: 8px;
  background: var(--progress-bg);
  border-radius: 4px;
  margin-left: 1rem;
  overflow: hidden;
}

.progress {
  height: 100%;
  background: var(--progress-fill);
  border-radius: 4px;
  transition: width 0.5s ease;
}

.progress.beginner { width: 20%; }
.progress.basic { width: 40%; }
.progress.intermediate { width: 60%; }
.progress.advanced { width: 80%; }
.progress.expert { width: 100%; }

/* Projects */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.projects-grid .btn-sm {
  margin-top: 1rem;
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  background: var(--accent-color);
  color: var(--primary-bg);
  border-radius: 20px;
}

/* Contact */
.contact-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
  margin-top: 1.5rem;
}

.contact-links a {
  padding: 0.7rem 1.3rem;
  background: var(--accent-color);
  color: var(--primary-bg);
  border-radius: 30px;
  text-decoration: none;
  box-shadow: 0 0 8px var(--accent-color);
  transition: var(--transition);
}

.contact-links a:hover {
  background: var(--hover-accent);
  transform: translateY(-3px);
  box-shadow: 0 0 12px var(--accent-color);
}

/* Footer */
footer {
  text-align: center;
  padding: 1rem;
  background: var(--primary-bg);
  border-top: 1px solid var(--secondary-bg);
  color: #9ca3af;
  font-size: 0.9rem;
}

/* Fade-in Animation */
.fade {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Staggered Animation */
.skills-grid .card:nth-child(1),
.projects-grid .card:nth-child(1) { transition-delay: 0.1s; }
.skills-grid .card:nth-child(2),
.projects-grid .card:nth-child(2) { transition-delay: 0.2s; }
.skills-grid .card:nth-child(3),
.projects-grid .card:nth-child(3) { transition-delay: 0.3s; }
.skills-grid .card:nth-child(4),
.projects-grid .card:nth-child(4) { transition-delay: 0.4s; }
.skills-grid .card:nth-child(5),
.projects-grid .card:nth-child(5) { transition-delay: 0.5s; }
.skills-grid .card:nth-child(6),
.projects-grid .card:nth-child(6) { transition-delay: 0.6s; }

/* Responsive Adjustments */
@media (max-width: 768px) {
  .hero { padding: 3rem 1rem; }
  .hero h1 { font-size: 2rem; }
  .hero p { font-size: 1rem; }
  .section { padding: 2.5rem 1rem; }
  .section h2 { font-size: 1.8rem; }
  .card { padding: 1.2rem; }
  .skills-grid,
  .projects-grid { grid-template-columns: 1fr; }
  .progress-bar { width: 80px; }
}

/* Headings */
h1, h2, h3, h4, h5 {
  color: var(--accent-color);
  font-weight: 500;
}