:root{--primary:#0ea5e9;--primary-dark:#0284c7;--secondary:#8b5cf6;--success:#10b981;--warning:#f59e0b;--danger:#ef4444;--text:#1e293b;--text-light:#64748b;--bg:#f8fafc;--card-bg:#fff;--border:#e2e8f0;--shadow:0 4px 6px -1px rgba(0,0,0,.1)}*{margin:0;padding:0;box-sizing:border-box}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,sans-serif;line-height:1.6;color:var(--text);background:var(--bg)}.header{background:linear-gradient(135deg,#0f172a,#1e293b);color:#fff;padding:2rem 0}.container{max-width:1200px;margin:0 auto;padding:0 1.5rem}.header-content{text-align:center}.logo{font-size:2rem;font-weight:700;margin-bottom:.5rem}.logo a{color:#fff;text-decoration:none}.tagline{opacity:.85;font-size:1.1rem}.nav{background:#fff;border-bottom:1px solid var(--border);position:-webkit-sticky;position:sticky;top:0;z-index:100;box-shadow:var(--shadow)}.nav-inner{display:flex;gap:.5rem;padding:.75rem 0;overflow-x:auto}.nav a{color:var(--text-light);text-decoration:none;padding:.5rem 1rem;border-radius:20px;font-size:.875rem;font-weight:500;white-space:nowrap;transition:all .2s}.nav a.active,.nav a:hover{background:var(--primary);color:#fff}main{padding:2rem 0}.category-section{margin-bottom:3rem}.category-title{font-size:1.5rem;font-weight:700;margin-bottom:1.5rem;color:var(--text);display:flex;align-items:center;gap:.5rem}.calculator-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));grid-gap:1.5rem;gap:1.5rem}.calculator-card{background:var(--card-bg);border:1px solid var(--border);border-radius:12px;padding:1.5rem;transition:all .3s ease;cursor:pointer;text-decoration:none;color:inherit;display:block}.calculator-card:hover{border-color:var(--primary);box-shadow:0 8px 30px rgba(14,165,233,.15);transform:translateY(-2px)}.calculator-card h3{font-size:1.125rem;font-weight:600;margin-bottom:.5rem}.calculator-card p{color:var(--text-light);font-size:.875rem}.calculator-container{max-width:800px;margin:0 auto}.calculator-form{background:var(--card-bg);border:1px solid var(--border);border-radius:12px;padding:2rem;margin-bottom:2rem}.form-group{margin-bottom:1.5rem}.form-group label{display:block;font-weight:500;margin-bottom:.5rem;color:var(--text)}.form-group input,.form-group select{width:100%;padding:.75rem 1rem;border:1px solid var(--border);border-radius:8px;font-size:1rem;transition:border-color .2s}.form-group input:focus,.form-group select:focus{outline:none;border-color:var(--primary)}.form-group .hint{font-size:.75rem;color:var(--text-light);margin-top:.25rem}.result-group{background:linear-gradient(135deg,#f0f9ff,#e0f2fe);border:1px solid var(--primary);border-radius:12px;padding:1.5rem;margin-top:2rem}.result-group h4{font-size:1rem;font-weight:600;margin-bottom:1rem;color:var(--primary-dark)}.result-item{display:flex;justify-content:space-between;padding:.75rem 0;border-bottom:1px solid var(--border)}.result-item:last-child{border-bottom:none}.result-label{color:var(--text-light)}.result-value{font-weight:600;color:var(--text)}.content-section{background:var(--card-bg);border:1px solid var(--border);border-radius:12px;padding:2rem;margin-bottom:2rem}.content-section h2{font-size:1.25rem;font-weight:700;margin-bottom:1rem;color:var(--text)}.content-section h3{font-size:1rem;font-weight:600;margin:1.5rem 0 .75rem}.content-section p{margin-bottom:1rem;color:var(--text-light)}.content-section ol,.content-section ul{margin:1rem 0;padding-left:1.5rem}.content-section li{margin:.5rem 0}.formula-box{background:#1e293b;color:#e2e8f0;padding:1.5rem;border-radius:8px;font-family:Courier New,monospace;margin:1rem 0;overflow-x:auto}.faq-item{border-bottom:1px solid var(--border);padding:1rem 0}.faq-item:last-child{border-bottom:none}.faq-question{font-weight:600;color:var(--text);margin-bottom:.5rem}.faq-answer{color:var(--text-light)}.disclaimer{background:#fef3c7;border:1px solid #f59e0b;border-radius:8px;padding:1rem;margin:2rem 0;text-align:center;color:#92400e;font-size:.875rem}footer{background:#0f172a;color:#fff;padding:2rem 0;text-align:center}footer p{opacity:.7;font-size:.875rem}@media (max-width:768px){.calculator-grid{grid-template-columns:1fr}.calculator-form{padding:1rem}}