:root {
  --bg: #f8f9ff;
  --card: #ffffff;
  --muted: #64748b;
  --text: #1e293b;
  --accent: #3b82f6;
  --accent-2: #10b981;
  --accent-3: #f59e0b;
  --accent-4: #ec4899;
  --border: #e2e8f0;
  --shadow: 0 4px 20px rgba(59, 130, 246, 0.08);
  --shadow-lg: 0 10px 40px rgba(59, 130, 246, 0.12);
  --gradient-1: linear-gradient(135deg, #15d425 0%, #15d425 100%);
  --gradient-2: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --gradient-3: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  --gradient-4: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
html {
  scroll-behavior: smooth;
}
body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, "Helvetica Neue", Arial, "Apple Color Emoji", "Segoe UI Emoji";
  background: linear-gradient(135deg, #f00 0%, rgb(222, 212, 16) 100%);
  background-attachment: fixed;
  color: var(--text);
  line-height: 1.7;
}

.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px;
}

.hero {
  margin-top: 32px;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 24px;
  padding: 48px 40px;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(59, 130, 246, 0.15) 0%, transparent 70%);
  pointer-events: none;
}
.hero h2 {
  margin: 0 0 16px;
  font-size: 42px;
  font-weight: 800;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero .lede {
  margin: 0 0 28px;
  color: var(--muted);
  line-height: 1.8;
  font-size: 18px;
  max-width: 900px;
}
.cta-row {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.site-header {
  border-bottom: 3px solid rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(20px);
  background: rgba(255, 255, 255, 0.95);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  position: sticky;
  top: 0;
  z-index: 100;
}
.site-header h1 {
  margin: 0 0 8px;
  font-size: 36px;
  font-weight: 900;
  letter-spacing: -0.5px;
  background: var(--gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.subtitle {
  margin: 0;
  color: var(--muted);
  font-size: 16px;
  font-weight: 500;
}

.controls {
  margin-top: 32px;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 20px;
  padding: 32px;
  box-shadow: var(--shadow-lg);
  display: grid;
  gap: 24px;
}

.control-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.control-label {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
}

.control-input, select, input[type="number"] {
  background: var(--bg);
  color: var(--text);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: 12px 16px;
  outline: none;
  font-size: 15px;
  transition: all 0.2s ease;
}
.control-input:focus, select:focus, input[type="number"]:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
  background: #ffffff;
}

.optimizers-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  padding: 8px 4px;
}

.opt-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  border: 2px solid var(--border);
  border-radius: 12px;
  background: var(--bg);
  cursor: pointer;
  transition: all 0.2s ease;
  min-width: 0;
}
.opt-item:hover {
  border-color: var(--accent);
  background: #ffffff;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.1);
}

.opt-item input[type="checkbox"] {
  accent-color: var(--accent);
  width: 18px;
  height: 18px;
  cursor: pointer;
}
.opt-item span {
  font-weight: 500;
  overflow-wrap: break-word;
  word-break: break-word;
  min-width: 0;
}

.actions {
  display: flex;
  gap: 10px;
}

.btn {
  padding: 14px 28px;
  border-radius: 14px;
  border: 2px solid var(--border);
  color: var(--text);
  background: var(--bg);
  cursor: pointer;
  font-size: 16px;
  font-weight: 600;
  transition: all 0.2s ease;
  text-decoration: none;
  display: inline-block;
}
.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
}
.btn.primary {
  background: var(--gradient-3);
  border: none;
  color: #ffffff;
  font-weight: 700;
  box-shadow: 0 4px 20px rgba(79, 172, 254, 0.4);
}
.btn.primary:hover {
  box-shadow: 0 8px 30px rgba(79, 172, 254, 0.5);
}
.btn.cta { 
  background: var(--gradient-1);
  color: #ffffff;
  border: none;
  font-weight: 700;
  box-shadow: 0 4px 20px rgba(102, 126, 234, 0.4);
}
.btn.cta:hover {
  box-shadow: 0 8px 30px rgba(102, 126, 234, 0.5);
}
.btn.outline {
  background: var(--gradient-1);
  border: none;
  color: #ffffff;
  font-weight: 700;
  box-shadow: 0 4px 20px rgba(102, 126, 234, 0.4);
}
.btn.outline:hover { 
  box-shadow: 0 8px 30px rgba(102, 126, 234, 0.5);
  color: #ffffff;
}
.btn.subtle {
  background: var(--bg);
  border: 2px solid var(--border);
}
.btn.subtle:hover {
  border-color: var(--accent);
  background: #ffffff;
}

.blog {
  margin-top: 32px;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 24px;
  padding: 48px;
  box-shadow: var(--shadow-lg);
}
.blog h2 {
  margin-top: 0;
  margin-bottom: 24px;
  font-size: 32px;
  font-weight: 800;
  color: var(--text);
}
.blog h3 {
  margin-top: 48px;
  margin-bottom: 16px;
  font-size: 24px;
  font-weight: 700;
  color: var(--text);
  position: relative;
  padding-left: 20px;
}
.blog h3::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 28px;
  background: var(--gradient-1);
  border-radius: 3px;
}
.blog p {
  color: var(--text);
  line-height: 1.8;
  font-size: 16px;
  margin-bottom: 16px;
}
.blog ul {
  padding-left: 24px;
  margin: 20px 0;
}
.blog li {
  margin: 12px 0;
  color: var(--text);
  line-height: 1.7;
}
.blog li strong {
  color: var(--accent);
}
.blog a { 
  color: var(--accent); 
  text-decoration: none; 
  font-weight: 600;
  border-bottom: 2px solid transparent;
  transition: border-color 0.2s ease;
}
.blog a:hover { 
  border-bottom-color: var(--accent);
}

blockquote {
  margin: 32px 0;
  padding: 24px 28px;
  border-left: 5px solid var(--accent);
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.05), rgba(16, 185, 129, 0.05));
  color: var(--text);
  border-radius: 12px;
  font-style: italic;
  font-size: 18px;
  line-height: 1.7;
}

.viz-placeholder {
  margin: 32px 0;
  padding: 40px 24px;
  border: 3px dashed var(--border);
  border-radius: 16px;
  color: var(--muted);
  background: var(--bg);
  text-align: center;
  font-size: 15px;
}

.chart-card {
  margin-top: 32px;
  margin-bottom: 40px;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: 24px;
  padding: 32px;
  box-shadow: var(--shadow-lg);
}
.chart-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}
.chart-header h2 {
  margin: 0;
  font-size: 24px;
  font-weight: 700;
  color: var(--text);
}
.chart-note { 
  color: var(--muted); 
  margin: 0; 
  font-size: 14px;
}

.site-footer {
  margin-top: 40px;
  padding: 32px 0;
  border-top: 3px solid rgba(255, 255, 255, 0.3);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
}
.site-footer small { 
  color: var(--muted); 
  font-size: 14px;
}

canvas { width: 100% !important; height: auto !important; }

.viz-image {
  border-radius: 16px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
  border: 2px solid var(--border);
}

code {
  background: var(--bg);
  color: var(--accent);
  padding: 3px 8px;
  border-radius: 6px;
  font-family: 'Monaco', 'Courier New', monospace;
  font-size: 14px;
}

/* ── Optimizer category headers (comment 2.1) ─────────────────────────────── */

.opt-category-header {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 4px 6px;
  border-bottom: 1px solid var(--border);
  margin-top: 8px;
}

.opt-category-header:first-child {
  margin-top: 0;
}

.opt-category-dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

.opt-category-name {
  font-size: 13px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.2px;
}

.opt-category-desc {
  font-size: 12px;
  color: var(--muted);
  font-style: italic;
}

.opt-color-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.opt-item:hover {
  border-color: var(--opt-color, var(--accent));
}

.opt-item input[type="checkbox"]:checked ~ span {
  font-weight: 600;
}

/* ── Configuration badge (comment 3.3) ───────────────────────────────────── */

.config-badge {
  margin-top: 20px;
  padding: 18px 22px;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.04), rgba(16, 185, 129, 0.04));
  border: 1.5px solid var(--border);
  border-radius: 14px;
  font-size: 13px;
}

.config-badge-title {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--muted);
  margin-bottom: 12px;
}

.config-badge-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 10px 24px;
}

.config-badge-full {
  grid-column: 1 / -1;
}

.config-badge-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.config-badge-label {
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--muted);
}

.config-badge-value {
  font-size: 13px;
  font-weight: 500;
  color: var(--text);
}

.config-mode-hard {
  color: #ef4444;
  font-weight: 700;
}

.config-mode-regular {
  color: #3b82f6;
  font-weight: 700;
}

/* Additional fun styling */
strong {
  font-weight: 700;
}

h4 {
  font-weight: 700;
  font-size: 18px;
}

/* Smooth animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero, .blog, .controls, .chart-card {
  animation: fadeIn 0.6s ease-out;
}

/* Link hover effects in CTA boxes */
.blog a[href^="#"] {
  transition: all 0.2s ease;
}

.blog a[href^="#"]:hover {
  transform: translateY(-1px);
}

/* Responsive adjustments */
@media (max-width: 768px) {
  .hero h2 {
    font-size: 32px;
  }
  
  .hero {
    padding: 32px 24px;
  }
  
  .blog {
    padding: 32px 24px;
  }
  
  .controls {
    padding: 24px;
  }
  
  .site-header h1 {
    font-size: 28px;
  }
  
  .cta-row {
    flex-direction: column;
  }
  
  .btn {
    width: 100%;
    text-align: center;
  }
}