:root {
  --primary: #6D28D9;
  --primary-dark: #4C1D95;
  --bg-dark: #0a0a0a;
  --bg-card: transparent; /* default transparent card background */
  --text-main: #ffffff;
  --text-muted: #a3a3b8;      /* same as #94a3b8 */
  --border-color: rgba(255,255,255,0.2); /* card border in dark theme */
  --icon-bg: rgba(255,255,255,0.05);    /* icon box background */
  --icon-border: rgba(255,255,255,0.15); /* icon box border */
  --subtitle-color: #94a3b8; /* for dark theme */
  --card-border: rgba(255, 255, 255, 0.2);   /* dark theme border */
  --card-hover-border: rgba(255, 255, 255, 0.4);
  --card-hover-bg: rgba(255, 255, 255, 0.05);
  --text-h1: linear-gradient(to right, #ffffff, #a78bfa);
  --nav-a: white;
  --navbar: rgba(0, 0, 0, 0.8);
}
body.light-theme {
  --bg-dark: #ffffff;
  --bg-card: #f5f5f5;
  --text-main: #1a1a1a;
  --text-muted: #4b5563;
  --border-color: rgba(0,0,0,0.1);
  --icon-bg: rgba(0,0,0,0.05);
  --icon-border: rgba(0,0,0,0.15);
  --subtitle-color: #6b7280; /* slightly darker for light theme */
  --bg-card: rgba(245, 245, 245, 0.6);   /* transparent light card background */
  --card-border: rgba(162, 0, 255, 0.384);     /* dark border for light theme */
  --card-hover-border: rgba(0, 0, 0, 0.2);
  --card-hover-bg: rgba(0, 0, 0, 0.04);
  --text-h1: linear-gradient(to right, #1a1a1a, #7c3aed);
  --nav-a: black;
  --navbar: rgba(197, 194, 194, 0.8);
}
  * {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  scroll-behavior: smooth;
}
body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
}
body::before {
  content: '';
  position: fixed;
  top: 50%;
  left: 50%;
  width: 800px;
  height: 800px;
  border-radius: 50%;
  background: 
    radial-gradient(circle, rgba(109,40,217,0.15) 0%, rgba(109,40,217,0.05) 70%, transparent 100%),
    repeating-radial-gradient(
      circle,
      rgba(255,255,255,0.02) 0px,
      rgba(255,255,255,0.02) 2px,
      transparent 2px,
      transparent 4px
    );
  transform: translate(-50%, -50%) scale(var(--circle-scale, 1));
  z-index: -1;
  pointer-events: none;
  transition: transform 0.1s ease-out;
  filter: blur(40px); /* smooth glow + soft edges */
}
#theme-toggle {
  position: fixed;       /* stays on screen */
  bottom: 20px;          /* distance from bottom */
  left: 20px;            /* distance from left */
  background: transparent; /* violet */
  color: var(--primary);           /* white icon */
  border: 2px solid var(--primary);
  padding: 20px;         /* size */
  border-radius: 50%;    /* circle */
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;     /* icon size */
  z-index: 10000;        /* always on top */
  box-shadow: 0 4px 20px rgba(0,0,0,0.3);
  transition: background 0.3s ease, transform 0.2s;
}
#theme-toggle:hover {
  background: var(--primary-dark); /* darker violet */
  transform: scale(1.1);
}
/* Typography */
h1, h2, h3, h4 {
  color: var(--text-main);
  font-weight: 700;
  line-height: 1.2;
}
p, .hero-text, .subtitle, .card-content p {
  color: var(--text-muted);
}
a, .nav-links a {
  color: var(--text-muted);
}
.btn-primary, .btn-secondary, .btn-projects {
  color: var(--text-main);
}
h1 { font-size: 3.5rem; letter-spacing: -0.02em; }
h2 { font-size: 2.5rem; margin-bottom: 1rem; }
h3 { font-size: 1.5rem; margin-bottom: 0.5rem; }
p { color: var(--text-muted); margin-bottom: 1.5rem; }
/* Navigation */
.navbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--navbar);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: white;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.logo span { color: var(--primary); }

.nav-links {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  list-style: none;
}
.nav-links a {
  color: white;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s ease;
}
.nav-links a:hover, .nav-links a.active {
  color: var(--primary);
}
.nav-links a .active {
  display: flex;
  border-bottom: 2px solid var(--primary);
  flex-direction: column;
}
.btn-login {
  background: transparent;
  border: 1px solid var(--primary);
  color: var(--primary);
  padding: 12px 20px;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, transform 0.2s;
}
.btn-register:hover {
  background-color: var(--primary-dark);
  color: white;
  border: 2px solid var(--primary-dark);
  transform: translateY(-1px);
}
.btn-register {
  background: transparent;
  border: 1px solid var(--primary);
  color: var(--primary);
  padding: 12px 20px;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, transform 0.2s;
}
.btn-register:hover {
  background-color: var(--primary-dark);
  color: white;
  border: 2px solid var(--primary-dark);
  transform: translateY(-1px);
}
.hamburger {
  display: none;
  cursor: pointer;
  background: none;
  border: none;
  color: white;
  font-size: 1.5rem;
}
/* ================================
    SECTION CONTAINER
================================ */
section {
  padding: 6rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}
.section-title {
  text-align: center;
  margin-bottom: 4rem;
}
/* Services Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}
.card {
  background-color: var(--bg-card);
  padding: 2rem;
  border-radius: 1rem;
  border: 1px solid rgba(255, 255, 255, 0.05);
  transition: transform 0.3s ease, border-color 0.3s ease;
}
.card:hover {
  transform: translateY(-5px);
  border-color: var(--primary);
}
.card-icon {
  width: 50px;
  height: 50px;
  background-color: rgba(59, 130, 246, 0.1);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  margin-bottom: 1.5rem;
  font-size: 1.5rem;
}
/* ========================================
   Footer
   ======================================== */
.footer {
  background-color: var(--bg-card);
  padding: 5rem 0 3rem;
  position: relative;
  overflow: hidden;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
  margin-bottom: 4rem;
}
@media (min-width: 768px) {
  .footer-grid {
    grid-template-columns: 2fr 1fr 1fr 1fr;
  }
}
.footer-brand {
  max-width: 350px;
}
.footer-logo {
  color: var(--text-main);
  font-size: 1.75rem;
  font-family: var(--font-heading);
  font-weight: 900;
  margin-bottom: 1rem;
  margin-left: 3rem;
  display: inline-block;
}
.footer-logo span { color: var(--primary); }

.footer-tagline {
  line-height: 1.6;
  color: var(--text-muted);
  margin-left: 3rem;
}
.footer-column h3 {
  color: var(--text-main);
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-family: var(--font-body);
  font-weight: 600;
}
.footer-column ul {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  text-decoration: none;
  list-style: none;
}
.footer-column a {
  transition: all 0.2s;
  align-items: center;
  gap: 0.6rem;
  display: flex;
  text-decoration: none;
}
.footer-column a:hover {
  color: var(--color-primary);
  transform: translateX(5px);
}
.footer-bottom {
  text-align: center;
  padding-top: 3rem;
  border-top: 1px solid rgba(255,255,255,0.05);
  font-size: 0.9rem;
  color: #64748b;
}
/* ================================
    MOBILE RESPONSIVENESS
================================ */
@media (max-width: 768px) {
  h1 { font-size: 2.5rem; }
  h2 { font-size: 2rem; }
  
  .hamburger { display: block; }
  
  .nav-links {
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background-color: var(--navbar);
    flex-direction: column;
    padding: 2rem;
    gap: 1.5rem;
    transform: translateY(-150%);
    transition: transform 0.3s ease;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  }
  .nav-links.active {
    transform: translateY(0);
  }
}