:root {
  --clr-bg1: #121212;
  --clr-bg2: #1a1a1a;
  --clr-accent1: #3b82f6;
  --clr-accent2: #06b6d4;
  --clr-card-bg: rgba(30,30,30,0.85);
  --clr-text: #e0e0e0;
  --radius: 12px;
  --transition: 0.3s ease;
  --gap: 20px;
  --max-width: 800px;
}

*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
  color: var(--clr-text);
}

body {
  min-height: 100vh;
  padding: var(--gap);
  background: linear-gradient(135deg, var(--clr-bg1), var(--clr-bg2), var(--clr-bg1));
  background-size: 200% 200%;
  animation: gradientShift 12s infinite;
}
@keyframes gradientShift {
  0%   { background-position: 0% 50%; }
  50%  { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.topbar {
  width: 100%;
  background: rgba(30,30,30,0.95);
  backdrop-filter: blur(6px);
  padding: 12px 20px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
  position: fixed;
  top: 0;
  left: 0;
  z-index: 100;
}
.topbar-nav {
  display: flex;
  gap: 20px;
  justify-content: center;
}
.topbar-nav a {
  color: var(--clr-text);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s;
}
.topbar-nav a:hover {
  color: var(--clr-accent1);
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 100px auto var(--gap);
  background: var(--clr-card-bg);
  border-radius: var(--radius);
  backdrop-filter: blur(8px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.5);
  border: 1px solid rgba(255,255,255,0.1);
  overflow: hidden;
}

.header {
  text-align: center;
  padding: 25px var(--gap) 10px;
  font-size: 1.9rem;
  font-weight: 600;
}

.tabs {
  display: flex;
  justify-content: center;
  gap: 8px;
  padding: 10px var(--gap);
}
.tab {
  flex: 1;
  padding: 10px 0;
  background: var(--clr-card-bg);
  border-radius: var(--radius);
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  font-weight: 500;
}
.tab.active {
  background: var(--clr-accent1);
  color: #fff;
  box-shadow: 0 4px 12px rgba(59,130,246,0.4);
}
.tab:hover:not(.active) {
  background: rgba(59,130,246,0.2);
}

#md-content {
  padding: 0 var(--gap) var(--gap);
  line-height: 1.6;
}
#md-content h1,
#md-content h2,
#md-content h3 {
  margin: 1em 0 0.5em;
  font-weight: 600;
}
#md-content p {
  margin: 0.75em 0;
}
#md-content a {
  color: var(--clr-accent2);
  text-decoration: underline;
}
#md-content a:hover {
  opacity: 0.8;
}
#md-content ul,
#md-content ol {
  margin: 0.75em 0 0.75em 1.5em;
}
#md-content code {
  background: rgba(255,255,255,0.1);
  padding: 2px 4px;
  border-radius: 4px;
  font-family: monospace;
}
#md-content pre code {
  display: block;
  background: rgba(255,255,255,0.1);
  padding: 12px;
  overflow-x: auto;
  border-radius: 4px;
}
#md-content blockquote {
  margin: 1em 0;
  padding-left: 1em;
  border-left: 4px solid rgba(255,255,255,0.2);
  background: rgba(255,255,255,0.05);
}