/* Premium dark theme for SQL practice landing page */
:root{
  --bg:#0b1018;
  --bg-2:#070c13;
  --panel:#0f1522;
  --panel-2:#0b1220;
  --muted:#95a2b3;
  --accent:#7c5cff;
  --accent-2:#27d3c2;
  --text:#e6eef6;
  --border:rgba(255,255,255,0.06);
  --glow:rgba(124,92,255,0.25);
  --success:#10b981;
  --warning:#f59e0b;
}

*{box-sizing:border-box}
html,body{height:100%;margin:0}
body{
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background:radial-gradient(1200px 600px at 10% 0%, #111a2a 0%, transparent 55%),
             radial-gradient(800px 500px at 90% 0%, #0f1b33 0%, transparent 60%),
             linear-gradient(180deg, var(--bg), var(--bg-2) 100%);
  color:var(--text);
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
}

.ambient{
  position:fixed;
  inset:0;
  background:
    radial-gradient(600px 200px at 20% 20%, rgba(124,92,255,0.15), transparent 60%),
    radial-gradient(500px 220px at 85% 10%, rgba(39,211,194,0.12), transparent 60%);
  pointer-events:none;
  z-index:0;
}

.page{
  position:relative;
  z-index:1;
  max-width:1200px;
  margin:0 auto;
  padding:24px;
}

/* Navigation */
.topbar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  margin-bottom:56px;
  padding:16px 0;
}

.brand{
  display:flex;
  align-items:center;
  gap:10px;
  font-weight:700;
  font-size:16px;
}

.brand-dot{
  width:10px;height:10px;border-radius:50%;
  background:linear-gradient(180deg, var(--accent), #4d3cff);
  box-shadow:0 0 12px var(--glow);
}

.nav{display:flex;gap:28px}
.nav-link{
  color:var(--muted);
  text-decoration:none;
  font-size:14px;
  transition:color 0.2s;
}
.nav-link:hover{color:var(--text)}

.nav-right{display:flex;align-items:center;gap:12px}

.btn-secondary{
  background:transparent;
  color:var(--text);
  border:1px solid var(--border);
  border-radius:10px;
  padding:8px 14px;
  font-size:13px;
  cursor:pointer;
  transition:all 0.2s;
}
.btn-secondary:hover{border-color:rgba(255,255,255,0.2);background:rgba(255,255,255,0.02)}

/* Main Stack */
.stack{display:flex;flex-direction:column;gap:48px}

/* Hero Section */
.hero-section{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:48px;
  align-items:center;
  margin-bottom:20px;
}

.hero-content{padding:20px 0}
.eyebrow{letter-spacing:0.22em;text-transform:uppercase;color:#7f93b1;font-size:11px;margin:0 0 12px}

.hero-title{
  margin:0 0 12px;
  font-size:42px;
  line-height:1.2;
  font-weight:700;
}

.hero-subtitle{
  color:var(--muted);
  margin:0 0 20px;
  font-size:16px;
  line-height:1.6;
  max-width:520px;
}

.hero-actions{
  display:flex;
  gap:12px;
}

.btn-primary{
  background:linear-gradient(180deg,var(--accent),#4d3cff);
  color:white;
  padding:12px 24px;
  border-radius:10px;
  border:none;
  cursor:pointer;
  font-weight:600;
  font-size:14px;
  box-shadow: 0 8px 20px rgba(124,92,255,0.3);
  transition:all 0.2s;
}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 12px 28px rgba(124,92,255,0.35)}
.btn-primary:active{transform:translateY(0)}

.btn-primary.btn-lg{padding:14px 28px;font-size:15px}

.btn-ghost{
  background:transparent;
  color:var(--text);
  border:1px solid var(--border);
  border-radius:10px;
  padding:12px 24px;
  font-size:14px;
  cursor:pointer;
  transition:all 0.2s;
}
.btn-ghost:hover{border-color:rgba(255,255,255,0.2);background:rgba(255,255,255,0.03)}

.btn-ghost.btn-lg{padding:14px 28px;font-size:15px}

.hero-stats{
  display:flex;
  flex-direction:column;
  gap:14px;
}

.stat-badge{
  padding:16px;
  border-radius:14px;
  background:linear-gradient(180deg, rgba(255,255,255,0.035), rgba(255,255,255,0.015));
  border:1px solid var(--border);
  text-align:center;
}

.stat-num{
  display:block;
  font-size:20px;
  font-weight:700;
  color:var(--accent);
  margin-bottom:6px;
}

.stat-text{
  display:block;
  font-size:12px;
  color:var(--muted);
  letter-spacing:0.05em;
}

/* How It Works */
.how-it-works{
  text-align:center;
  padding:28px 0;
}

.how-it-works h2{
  margin:0 0 8px;
  font-size:28px;
}

.how-it-works p{color:var(--muted);margin:0}

.steps{
  display:grid;
  grid-template-columns:repeat(4,1fr);
  gap:18px;
  margin-top:32px;
}

.step-card{
  padding:24px 18px;
  border-radius:14px;
  background:linear-gradient(180deg, rgba(255,255,255,0.025), rgba(255,255,255,0.01));
  border:1px solid var(--border);
  text-align:center;
}

.step-number{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  width:40px;height:40px;
  border-radius:50%;
  background:linear-gradient(180deg,var(--accent),#4d3cff);
  color:white;
  font-weight:700;
  margin-bottom:12px;
}

.step-card h3{margin:0 0 8px;font-size:16px}
.step-card p{margin:0;color:var(--muted);font-size:13px;line-height:1.5}

/* Difficulty Section */
.difficulty-section{text-align:center;padding:20px 0}
.difficulty-section h2{margin:0 0 8px;font-size:28px}
.section-subtitle{color:var(--muted);margin:0;font-size:15px}

.difficulty-grid{
  display:grid;
  grid-template-columns:repeat(3,1fr);
  gap:18px;
  margin-top:28px;
}

.difficulty-card{
  padding:28px 24px;
  border-radius:14px;
  background:linear-gradient(180deg, rgba(255,255,255,0.025), rgba(255,255,255,0.01));
  border:1px solid var(--border);
  text-align:center;
  transition:all 0.3s;
}
.difficulty-card:hover{
  border-color:rgba(255,255,255,0.12);
  background:linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.015));
  transform:translateY(-4px);
}

.difficulty-badge{
  display:inline-block;
  padding:6px 12px;
  border-radius:20px;
  font-size:11px;
  font-weight:600;
  margin-bottom:12px;
  letter-spacing:0.05em;
}

.difficulty-card.easy .difficulty-badge{
  background:rgba(16,185,129,0.15);
  color:#6ee7b7;
}
.difficulty-card.medium .difficulty-badge{
  background:rgba(245,158,11,0.15);
  color:#fbbf24;
}
.difficulty-card.hard .difficulty-badge{
  background:rgba(239,68,68,0.15);
  color:#fca5a5;
}

.difficulty-card h3{margin:0 0 8px;font-size:18px;font-weight:600}
.difficulty-card p{margin:0 0 16px;color:var(--muted);font-size:13px;line-height:1.5}

.count-badge{
  display:inline-block;
  padding:6px 10px;
  border-radius:8px;
  background:rgba(255,255,255,0.04);
  font-size:12px;
  color:var(--muted);
  margin-bottom:16px;
}

.btn-card{
  background:transparent;
  color:var(--accent);
  border:1px solid var(--border);
  border-radius:8px;
  padding:9px 16px;
  font-size:13px;
  cursor:pointer;
  transition:all 0.2s;
}
.btn-card:hover{
  border-color:var(--accent);
  background:rgba(124,92,255,0.1);
}

/* Topics Section */
.topics-section{text-align:center;padding:20px 0}
.topics-section h2{margin:0 0 8px;font-size:28px}

.topics-grid{
  display:grid;
  grid-template-columns:repeat(6,1fr);
  gap:14px;
  margin-top:28px;
}

.topic-card{
  padding:20px 14px;
  border-radius:12px;
  background:linear-gradient(180deg, rgba(255,255,255,0.025), rgba(255,255,255,0.01));
  border:1px solid var(--border);
  text-align:center;
  transition:all 0.2s;
  cursor:pointer;
}
.topic-card:hover{
  border-color:rgba(255,255,255,0.12);
  background:linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.015));
}

.topic-icon{font-size:24px;display:block;margin-bottom:8px}
.topic-card h4{margin:0 0 4px;font-size:13px;font-weight:600}
.topic-desc{margin:0;font-size:11px;color:var(--muted)}

/* Features Section */
.features-section{text-align:center;padding:20px 0}
.features-section h2{margin:0 0 28px;font-size:28px}

.features-grid{
  display:grid;
  grid-template-columns:repeat(4,1fr);
  gap:18px;
}

.feature-box{
  padding:24px;
  border-radius:14px;
  background:linear-gradient(180deg, rgba(255,255,255,0.025), rgba(255,255,255,0.01));
  border:1px solid var(--border);
  text-align:center;
}

.feature-icon{
  font-size:28px;
  margin-bottom:12px;
  display:block;
}

.feature-box h4{margin:0 0 8px;font-size:15px;font-weight:600}
.feature-box p{margin:0;color:var(--muted);font-size:13px;line-height:1.5}

/* CTA Section */
.cta-section{
  text-align:center;
  padding:48px 28px;
  border-radius:16px;
  background:linear-gradient(180deg, rgba(124,92,255,0.08), rgba(39,211,194,0.04));
  border:1px solid rgba(124,92,255,0.2);
}

.cta-section h2{margin:0 0 8px;font-size:28px}
.cta-section p{margin:0 0 20px;color:var(--muted);font-size:15px}

/* Footer */
.footer{
  margin-top:40px;
  text-align:center;
  padding:24px 0;
  color:var(--muted);
  font-size:12px;
  border-top:1px solid var(--border);
}

/* Responsive */
@media (max-width:1024px){
  .hero-section{grid-template-columns:1fr;gap:32px}
  .steps{grid-template-columns:repeat(2,1fr)}
  .difficulty-grid{grid-template-columns:1fr}
  .topics-grid{grid-template-columns:repeat(3,1fr)}
  .features-grid{grid-template-columns:repeat(2,1fr)}
}

@media (max-width:768px){
  .topbar{flex-wrap:wrap;margin-bottom:36px}
  .nav{display:none}
  .page{padding:16px}
  .stack{gap:32px}
  
  .hero-title{font-size:32px}
  .hero-subtitle{font-size:15px}
  .hero-stats{flex-direction:row;gap:12px;font-size:12px}
  .stat-badge{padding:12px}
  .stat-num{font-size:16px}
  
  .steps{grid-template-columns:1fr;gap:14px}
  .step-card{padding:18px 14px}
  
  .difficulty-grid{gap:14px}
  .topics-grid{grid-template-columns:repeat(2,1fr)}
  .features-grid{grid-template-columns:1fr}
  
  .cta-section{padding:32px 20px}
}