:root {
  --color-primary: #5B8DEF;
  --color-secondary: #00C9A7;
  --color-bg: #F8FAFC;
  --color-card: #FFFFFF;
  --color-text: #1f2937;
  --color-muted: #64748b;
  --color-border: #e2e8f0;
  --radius-lg: 18px;
  --radius-md: 14px;
  --shadow-soft: 0 10px 30px rgba(15, 23, 42, 0.06);
  --shadow-hover: 0 16px 40px rgba(91, 141, 239, 0.16);
}

* { box-sizing: border-box; }
body {
  font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
}

.navbar {
  backdrop-filter: blur(8px);
  background: rgba(255,255,255,0.92);
  border-bottom: 1px solid rgba(226,232,240,0.6);
}
.navbar-brand {
  font-weight: 700;
  letter-spacing: 0.2px;
  color: var(--color-primary);
}

.hero {
  padding: 5rem 0 3.5rem;
}
.hero-card {
  background: linear-gradient(125deg, #ffffff, #f2f7ff);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  padding: 2.5rem;
}

.section-title {
  font-size: 1.7rem;
  font-weight: 700;
  margin-bottom: 1rem;
}

.card-premium,
.calculator-card,
.content-card {
  border: 1px solid var(--color-border);
  background: var(--color-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  transition: all .25s ease;
}
.card-premium:hover,
.calculator-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.ad-banner {
  margin: 1.25rem 0;
  border: 2px dashed #cbd5e1;
  border-radius: var(--radius-md);
  background: #f8fbff;
  padding: 1.2rem;
  color: #64748b;
  text-align: center;
  font-weight: 600;
}

.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.2rem;
}

.calculator-card {
  padding: 1.2rem;
  text-decoration: none;
  color: inherit;
}

.form-control, .form-select {
  border-radius: 12px;
  border-color: #dbe4f0;
  padding: .65rem .8rem;
}
.form-control:focus, .form-select:focus {
  box-shadow: 0 0 0 .2rem rgba(91, 141, 239, .15);
  border-color: var(--color-primary);
}

.btn-primary {
  background: var(--color-primary);
  border-color: var(--color-primary);
  border-radius: 12px;
}
.btn-secondary {
  background: var(--color-secondary);
  border-color: var(--color-secondary);
  border-radius: 12px;
}

.result-box {
  border: 1px solid #dbe4f0;
  background: #f8fbff;
  border-radius: 12px;
  padding: .9rem;
  min-height: 54px;
}

.scientific-display {
  width: 100%;
  border: 1px solid var(--color-border);
  border-radius: 12px;
  text-align: right;
  font-size: 1.4rem;
  padding: .8rem;
  margin-bottom: .8rem;
  background: #f8fafc;
}
.keypad { display: grid; grid-template-columns: repeat(5, 1fr); gap: .5rem; }
.keypad button {
  border: 1px solid #dbe4f0;
  background: #fff;
  border-radius: 10px;
  padding: .55rem;
  font-weight: 600;
}
.keypad button:hover { background: #eef4ff; }

.breadcrumb-wrap {
  margin-top: 1rem;
}
.faq-item {
  background: #fff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 1rem;
  margin-bottom: .8rem;
}

footer {
  border-top: 1px solid #e2e8f0;
  color: #64748b;
}

@media (max-width: 768px) {
  .hero-card { padding: 1.5rem; }
  .keypad { grid-template-columns: repeat(4, 1fr); }
}