/* SimiBoost — shared styles */
:root {
  --bg: #0b1020;
  --bg-soft: #121a33;
  --card: #172042;
  --card-hover: #1d2952;
  --border: #27325a;
  --text: #e8ecf7;
  --muted: #9aa5c7;
  --accent: #5b8cff;
  --accent-2: #7c5bff;
  --success: #3ddc97;
  --warn: #ffb020;
  --danger: #ff5e7a;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --max: 1100px;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  background: radial-gradient(1200px 600px at 10% -10%, #1a2452 0%, transparent 60%),
              radial-gradient(1000px 500px at 110% 10%, #2a1a52 0%, transparent 55%),
              var(--bg);
  color: var(--text);
  font-family: "Inter", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s ease;
}
a:hover {
  color: #9cb7ff;
}

/* Layout */
.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(10px);
  background: rgba(11, 16, 32, 0.7);
  border-bottom: 1px solid var(--border);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  padding-bottom: 14px;
}
.logo {
  font-weight: 800;
  font-size: 20px;
  letter-spacing: 0.3px;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text);
}
.logo .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 0 14px rgba(91, 140, 255, 0.7);
}

.nav a {
  margin-left: 18px;
  color: var(--muted);
  font-weight: 500;
}
.nav a:hover {
  color: var(--text);
}

/* Hero */
.hero {
  padding: 70px 0 40px;
}
.hero h1 {
  font-size: 44px;
  line-height: 1.15;
  margin: 0 0 12px;
  background: linear-gradient(135deg, #ffffff, #b7c4ff 60%, #c9b7ff);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero p {
  color: var(--muted);
  font-size: 18px;
  max-width: 720px;
  margin: 0 0 22px;
}
.hero .badges {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.badge {
  display: inline-block;
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 12px;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.03);
}

/* Sections */
section {
  padding: 40px 0;
}
.section-title {
  font-size: 26px;
  margin: 0 0 8px;
}
.section-sub {
  color: var(--muted);
  margin: 0 0 24px;
}

/* Calculator */
.calc {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}
.calc-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}
.tab-btn {
  background: var(--bg-soft);
  color: var(--muted);
  border: 1px solid var(--border);
  padding: 8px 14px;
  border-radius: 999px;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  transition: all 0.15s ease;
}
.tab-btn:hover {
  color: var(--text);
  border-color: #3b4a80;
}
.tab-btn.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  border-color: transparent;
}
.calc-panel {
  display: none;
}
.calc-panel.active {
  display: block;
}
.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  margin-bottom: 18px;
}
.field label {
  display: block;
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 6px;
}
.field input {
  width: 100%;
  padding: 11px 13px;
  background: var(--bg-soft);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 15px;
  outline: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.field input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(91, 140, 255, 0.22);
}

.calc-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}
.btn {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  border: none;
  padding: 11px 18px;
  border-radius: 10px;
  font-weight: 600;
  cursor: pointer;
  font-size: 14px;
  transition: transform 0.08s ease, box-shadow 0.15s ease;
}
.btn:hover {
  box-shadow: 0 10px 24px rgba(91, 140, 255, 0.35);
  transform: translateY(-1px);
}
.btn.ghost {
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--border);
}
.btn.ghost:hover {
  color: var(--text);
  box-shadow: none;
}

.result {
  margin-top: 16px;
  padding: 14px 16px;
  background: rgba(61, 220, 151, 0.08);
  border: 1px solid rgba(61, 220, 151, 0.25);
  border-radius: 10px;
  color: #c8f3df;
  font-size: 15px;
  display: none;
}
.result.show {
  display: block;
}
.result strong {
  color: var(--success);
  font-size: 18px;
}
.result .hint {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 12.5px;
}
.formula {
  color: var(--muted);
  font-size: 13px;
  margin: -6px 0 14px;
  font-family: "JetBrains Mono", Menlo, Consolas, monospace;
  background: rgba(255, 255, 255, 0.03);
  border: 1px dashed var(--border);
  padding: 8px 10px;
  border-radius: 8px;
  display: inline-block;
}

/* Guides grid */
.guides {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
}
.guide-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease;
  display: block;
  color: var(--text);
}
.guide-card:hover {
  background: var(--card-hover);
  border-color: #3b4a80;
  transform: translateY(-2px);
}
.guide-card .num {
  font-family: "JetBrains Mono", monospace;
  color: var(--accent);
  font-size: 13px;
  letter-spacing: 0.1em;
  margin-bottom: 6px;
}
.guide-card h3 {
  margin: 0 0 8px;
  font-size: 18px;
}
.guide-card p {
  color: var(--muted);
  margin: 0 0 12px;
  font-size: 14px;
}
.guide-card .read {
  color: var(--accent);
  font-weight: 600;
  font-size: 13px;
}

/* Article pages */
.article {
  max-width: 780px;
  margin: 0 auto;
  padding: 40px 0 60px;
}
.article .back {
  color: var(--muted);
  font-size: 14px;
  display: inline-block;
  margin-bottom: 18px;
}
.article .back:hover {
  color: var(--text);
}
.article h1 {
  font-size: 34px;
  line-height: 1.2;
  margin: 0 0 10px;
}
.article .meta {
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 26px;
}
.article h2 {
  margin-top: 32px;
  font-size: 22px;
}
.article h3 {
  margin-top: 24px;
  font-size: 17px;
}
.article p,
.article li {
  color: #d7dcee;
  font-size: 16px;
}
.article ul,
.article ol {
  padding-left: 22px;
}
.article blockquote {
  margin: 20px 0;
  padding: 12px 16px;
  border-left: 3px solid var(--accent);
  background: rgba(91, 140, 255, 0.08);
  color: #d7dcee;
  border-radius: 6px;
}
.article code {
  background: var(--bg-soft);
  padding: 2px 6px;
  border-radius: 5px;
  font-size: 14px;
  border: 1px solid var(--border);
}

.next-prev {
  margin-top: 40px;
  display: flex;
  justify-content: space-between;
  gap: 14px;
  flex-wrap: wrap;
}
.next-prev a {
  background: var(--card);
  border: 1px solid var(--border);
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 14px;
  color: var(--text);
  transition: background 0.15s ease;
}
.next-prev a:hover {
  background: var(--card-hover);
}

/* Footer */
.site-footer {
  margin-top: 40px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 13px;
  padding: 22px 0;
  text-align: center;
}

@media (max-width: 640px) {
  .hero h1 {
    font-size: 32px;
  }
  .article h1 {
    font-size: 26px;
  }
  .nav a {
    margin-left: 12px;
    font-size: 14px;
  }
}