:root {
  --bg-color: #000000;
  --text-color: #ffffff;
  --border-color: #333333;
  --accent-hover: #222222;
  --transition-speed: 0.3s;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  padding: 1.5rem;
  background: var(--bg-color);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  flex: 1;
  text-decoration: none;
  text-align: center;
  font-size: 1.5rem;
  font-weight: bold;
  letter-spacing: 2px;
  color: var(--text-color);
  text-transform: uppercase;
}

.spacer { flex: 1; }

/* Nav Button - Improved Hitbox */
.nav-button {
  background: transparent;
  border: 1px solid transparent;
  cursor: pointer;
  z-index: 101;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 4px;
  transition: background-color 0.3s, border-color 0.3s;
  padding: 0;
}

.nav-button:hover {
  background-color: var(--accent-hover);
  border-color: var(--border-color);
}

.nav-icon, .nav-icon::before, .nav-icon::after {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-color);
  position: relative;
  transition: 0.3s;
  pointer-events: none;
}

.nav-icon::before, .nav-icon::after { content: ''; position: absolute; left: 0; }
.nav-icon::before { top: -8px; }
.nav-icon::after { top: 8px; }

/* Navigation Drawer */
.nav-menu {
  position: fixed;
  top: 0;
  left: -100%;
  width: 300px;
  height: 100%;
  background: var(--bg-color);
  border-right: 1px solid var(--border-color);
  padding: 5rem 2rem;
  transition: left var(--transition-speed);
  z-index: 1000;
}

.nav-menu.open { left: 0; }

.nav-menu ul { list-style: none; padding: 0; }

.nav-menu a {
  display: block;
  padding: 1rem 0;
  color: var(--text-color);
  text-decoration: none;
  font-size: 1.2rem;
  border-bottom: 1px solid #111;
}

.close-menu {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  background: none;
  border: none;
  color: white;
  font-size: 2rem;
  cursor: pointer;
}

/* Sections */
.content {
  max-width: 800px;
  margin: 0 auto;
  padding: 4rem 1.5rem;
}

.section {
  text-align: center;
  margin-bottom: 6rem;
}

h1 { font-size: 3rem; margin-bottom: 1rem; }
h2 { font-size: 1.5rem; margin-bottom: 2rem; text-transform: uppercase; letter-spacing: 1px; }

/* Buttons & Links */
.btn {
  display: inline-block;
  border: 1px solid var(--text-color);
  color: var(--text-color);
  padding: 0.8rem 2rem;
  text-decoration: none;
  margin: 0.5rem;
  transition: background 0.3s;
  background: transparent;
  cursor: pointer;
}

.btn:hover {
  background: var(--text-color);
  color: var(--bg-color);
}

.btn-primary {
  background: var(--text-color);
  color: var(--bg-color);
}

.btn-primary:hover {
  background: transparent;
  color: var(--text-color);
}

.projects-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.project-link {
  padding: 1.5rem;
  border: 1px solid var(--border-color);
  color: var(--text-color);
  text-decoration: none;
  transition: border-color 0.3s;
}

.project-link:hover {
  border-color: #888;
}

/* Footer */
.footer {
  text-align: center;
  padding: 4rem 1.5rem;
  border-top: 1px solid var(--border-color);
  font-size: 0.8rem;
  color: #666;
}

.overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.8);
  visibility: hidden;
  opacity: 0;
  transition: 0.3s;
  z-index: 500;
}

.overlay.show { visibility: visible; opacity: 1; }


/* --- Cobra Tail specific additions --- */

.hero .lead {
  max-width: 640px;
  margin: 0 auto 2rem;
  color: #aaa;
  font-size: 1.05rem;
}

.grad {
  background: linear-gradient(90deg, #10b981, #c0c0c0);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.btns {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 3rem;
}

.graphic {
  margin: 2rem auto 0;
  max-width: 100%;
}
.graphic svg { width: 100%; height: auto; display: block; }

/* Features grid — two columns on wider screens */
.features-grid {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  text-align: left;
}

.feature h3 {
  font-family: ui-monospace, 'SF Mono', Menlo, monospace;
  font-size: 1rem;
  letter-spacing: 1px;
  margin: 0 0 0.75rem;
  text-transform: uppercase;
  color: #c0c0c0;
}

.feature p {
  color: #aaa;
  font-size: 0.95rem;
  margin: 0;
}

code {
  font-family: ui-monospace, 'SF Mono', Menlo, monospace;
  background: #111;
  padding: 2px 6px;
  border-radius: 3px;
  color: #ccc;
  font-size: 0.85em;
  border: 1px solid var(--border-color);
}

/* Architecture tiers */
.tiers {
  display: flex;
  gap: 1rem;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
}

.tier {
  flex: 1;
  min-width: 200px;
  padding: 1.5rem;
  border: 1px solid var(--border-color);
  transition: border-color 0.3s;
}

.tier:hover { border-color: #888; }

.tier .lvl {
  color: #888;
  font-family: ui-monospace, 'SF Mono', Menlo, monospace;
  font-size: 0.72rem;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.tier h4 {
  font-size: 1.2rem;
  margin: 0 0 0.25rem;
}

.tier p {
  color: #888;
  font-style: italic;
  font-size: 0.9rem;
  margin: 0;
}

.arrow {
  color: #444;
  font-size: 1.6rem;
}

/* Technical overview block */
.specs {
  text-align: left;
  padding: 2.5rem;
  border: 1px solid var(--border-color);
}

.specs h2 { text-align: left; }

.specs-list {
  list-style: none;
  padding: 0;
  margin-top: 1.25rem;
}

.specs-list li {
  padding: 0.4rem 0;
  color: #aaa;
}

.specs-list li strong { color: var(--text-color); }

/* Quantum glow pulse */
@keyframes pulse { 0%, 100% { opacity: .3 } 50% { opacity: 1 } }
.q { animation: pulse 2s ease-in-out infinite; transform-origin: center; }

/* --- Mobile optimization (original + new) --- */
@media (max-width: 600px) {
  .header {
    justify-content: space-between;
    padding: 1rem;
  }

  .header .spacer { display: none; }

  .logo {
    flex: initial;
    font-size: 1.1rem;
    text-align: center;
    letter-spacing: 1px;
  }

  h1 { font-size: 2rem; }
  .arrow { transform: rotate(90deg); }
  .specs { padding: 1.5rem; }
}