:root {
  --primary-color: #3b82f6;
  --secondary-color: #1e40af;
  --bg-color: #0f172a;
  --bg-card: #1e293b;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --font-main: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --max-width: 1200px;
  --radius: 8px;
  --transition: all 0.3s ease;
}

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

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

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--secondary-color);
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

/* Header & Nav */
header {
  border-bottom: 1px solid var(--border-color);
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 100;
}

nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.logo {
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--text-main);
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-weight: 500;
}

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

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

/* Hero Section */
.hero {
  padding: 5rem 0;
  display: flex;
  align-items: center;
  gap: 4rem;
  min-height: 80vh;
}

.hero-content {
  flex: 1;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  line-height: 1.2;
  background: linear-gradient(to right, var(--primary-color), #a855f7);
  -webkit-background-clip: text;
  color: transparent;
}

.hero-subtitle {
  font-size: 1.5rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.hero-image {
  flex: 1;
  display: flex;
  justify-content: center;
}

.profile-img {
  width: 300px;
  height: 300px;
  object-fit: cover;
  border-radius: 50%;
  border: 4px solid var(--primary-color);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

.btn {
  display: inline-block;
  padding: 0.8rem 1.5rem;
  background-color: var(--primary-color);
  color: white;
  border-radius: var(--radius);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: var(--transition);
}

.btn:hover {
  background-color: var(--secondary-color);
  transform: translateY(-2px);
  color: white;
}

.btn-secondary {
  background-color: transparent;
  border: 1px solid var(--border-color);
  margin-left: 1rem;
}

.btn-secondary:hover {
  background-color: var(--bg-card);
  border-color: var(--text-muted);
}

/* Sections */
.section {
  padding: 4rem 0;
}

.section-title {
  font-size: 2.5rem;
  margin-bottom: 2rem;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: -5px;
  width: 60px;
  height: 4px;
  background: var(--primary-color);
  border-radius: 2px;
}

/* Cards (Projects, Notes, etc.) */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-5px);
  border-color: var(--primary-color);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.card-title {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
  color: var(--text-main);
}

.card-desc {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1rem;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: auto;
}

.tag {
  font-size: 0.8rem;
  padding: 0.2rem 0.6rem;
  background: rgba(59, 130, 246, 0.1);
  color: var(--primary-color);
  border-radius: 99px;
}

/* Footer */
footer {
  text-align: center;
  padding: 3rem 0;
  margin-top: 4rem;
  border-top: 1px solid var(--border-color);
  color: var(--text-muted);
}

/* Utilities */
.text-center {
  text-align: center;
}

.mb-1 {
  margin-bottom: 1rem;
}

.mb-2 {
  margin-bottom: 2rem;
}

.mt-2 {
  margin-top: 2rem;
}

/* Responsive */
@media (max-width: 768px) {
  .hero {
    flex-direction: column-reverse;
    text-align: center;
    padding: 3rem 0;
    gap: 2rem;
  }

  .hero-image {
    width: 100%;
  }

  .profile-img {
    width: 200px;
    height: 200px;
  }

  .nav-links {
    display: none;
    /* simple toggle later */
    position: absolute;
    top: 70px;
    left: 0;
    width: 100%;
    background: var(--bg-card);
    flex-direction: column;
    padding: 1rem;
    gap: 1rem;
    border-bottom: 1px solid var(--border-color);
  }

  .nav-links.active {
    display: flex;
  }

  .mobile-menu-btn {
    display: block;
  }

  .hero-title {
    font-size: 2.5rem;
  }
}