/* Calcxperts Global Design System */
:root {
  --primary: #0f172a;
  --primary-light: #1e293b;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --bg-light: #f8fafc;
  --card-bg: #ffffff;
  --border: #e2e8f0;
  --text-main: #334155;
  --text-muted: #64748b;
  --font-family: 'Inter', sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: var(--font-family);
  background-color: var(--bg-light);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
}

/* Navigation */
nav {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  padding: 1.2rem 5%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo { font-size: 1.5rem; font-weight: 800; color: var(--primary); letter-spacing: -0.5px; text-decoration: none; }
.logo span { color: var(--accent); }

/* Layout & Cards */
.container { max-width: 1000px; margin: 2rem auto; padding: 0 1rem; display: grid; gap: 2rem; }
@media(min-width: 800px) { .container { grid-template-columns: 1fr 1fr; } }
.container-single { max-width: 800px; margin: 3rem auto; padding: 0 1.5rem; }

.card {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 2rem;
  border: 1px solid var(--border);
  box-shadow: 0 4px 6px rgba(0,0,0,0.02);
}

h2 { color: var(--primary); margin-bottom: 1.5rem; font-weight: 700; }

/* Input Fields */
.input-group { margin-bottom: 1.2rem; }
label { display: block; font-size: 0.9rem; font-weight: 600; margin-bottom: 0.5rem; color: var(--text-muted); }
.input-wrapper { position: relative; display: flex; align-items: center; }
.prefix, .suffix { position: absolute; color: #94a3b8; font-weight: 600; }
.prefix { left: 1rem; } .suffix { right: 1rem; }

input[type="text"], input[type="number"], select, input[type="date"] {
  width: 100%;
  padding: 0.8rem 1rem;
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--primary);
  font-family: var(--font-family);
  background: var(--card-bg);
  transition: border-color 0.3s ease;
}

input:focus, select:focus { outline: none; border-color: var(--accent); }
input.has-prefix { padding-left: 2.2rem; }

/* Global Footer */
.global-footer { background: var(--card-bg); border-top: 1px solid var(--border); padding: 3rem 5%; margin-top: 4rem; }
.footer-content { max-width: 1200px; margin: 0 auto; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 2rem; }
.footer-links h4 { color: var(--primary); margin-bottom: 1rem; font-size: 1rem; }
.footer-links ul { list-style: none; padding: 0; line-height: 2; }
.footer-links a { color: var(--text-muted); text-decoration: none; transition: 0.3s; }
.footer-links a:hover { color: var(--accent); }
.footer-bottom { text-align: center; color: #94a3b8; font-size: 0.85rem; border-top: 1px solid var(--border); margin-top: 3rem; padding-top: 1.5rem; }

/* SEO Article Blocks */
.seo-article { grid-column: 1 / -1; background: var(--card-bg); padding: 3rem; border-radius: 16px; border: 1px solid var(--border); margin-top: 1rem; }
.seo-article h2 { font-size: 1.8rem; margin-bottom: 1rem; color: var(--primary); }
.seo-article h3 { font-size: 1.3rem; margin: 2rem 0 1rem; color: var(--primary); }
.seo-article p { margin-bottom: 1.2rem; font-size: 1.05rem; }
.seo-article ul { margin-bottom: 1.5rem; padding-left: 1.5rem; }
.formula-box { background: #eff6ff; padding: 1.5rem; border-radius: 8px; border-left: 4px solid var(--accent); font-family: monospace; font-size: 1.1rem; margin-bottom: 1.5rem; }