:root {
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --indigo-50: #eef2ff;
  --indigo-100: #e0e7ff;
  --indigo-600: #4f46e5;
  --slate-50: #f8fafc;
  --slate-100: #f1f5f9;
  --slate-200: #e2e8f0;
  --slate-400: #94a3b8;
  --slate-500: #64748b;
  --slate-600: #475569;
  --slate-700: #334155;
  --slate-900: #0f172a;
  --white: #ffffff;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Inter', -apple-system, sans-serif; background: var(--slate-50); color: var(--slate-900); line-height: 1.6; -webkit-font-smoothing: antialiased; }

/* Layout */
.container { max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }
.container-narrow { max-width: 1000px; margin: 0 auto; padding: 0 1.5rem; }
h1 { font-size: 2rem; font-weight: 900; margin-bottom: 1.5rem; letter-spacing: -0.04em; }
p { color: var(--slate-600); margin-bottom: 1.25rem; font-size: 1rem; }

header { background: rgba(255,255,255,0.8); backdrop-filter: blur(8px); border-bottom: 1px solid var(--slate-200); position: sticky; top: 0; z-index: 50; }
.header-inner { height: 4.5rem; display: flex; align-items: center; justify-content: space-between; }
.logo { display: flex; align-items: center; gap: 0.1rem; text-decoration: none; font-weight: 800; font-size: 1.35rem; color: var(--slate-900); letter-spacing: -0.04em; }
.logo-icon { background: var(--primary); color: white; width: 2.5rem; height: 2.5rem; border-radius: 0.75rem; display: flex; align-items: center; justify-content: center; box-shadow: var(--shadow-sm); }
.logo span { color: var(--primary); }

.nav-links { display: flex; gap: 2rem; }
.nav-links a { text-decoration: none; font-size: 0.875rem; font-weight: 600; color: var(--slate-600); transition: all 0.2s; }
.nav-links a:hover { color: var(--primary); transform: translateY(-1px); }

/* Hero */
.hero { background: radial-gradient(circle at top right, var(--indigo-50), transparent), var(--white); border-bottom: 1px solid var(--slate-200); padding: 7rem 0; text-align: center; }
.hero h1 { font-size: 4rem; font-weight: 900; letter-spacing: -0.05em; margin-bottom: 1.5rem; line-height: 1.1; }
.hero h1 span { color: var(--primary); }
.hero p { font-size: 1.25rem; color: var(--slate-600); max-width: 42rem; margin: 0 auto 2.5rem; font-weight: 450; }

/* Components */
.card { background: var(--white); border: 1px solid var(--slate-200); border-radius: var(--radius-2xl); padding: 2.5rem; box-shadow: var(--shadow-sm); }
.card-hover:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); border-color: var(--indigo-100); }
.card-icon { color: var(--primary); margin-bottom: 1.5rem; display: block; }
.card-icon i { width: 2.5rem; height: 2.5rem; }
.card h2 { font-size: 1.25rem; font-weight: 800; margin-bottom: 0.75rem; letter-spacing: -0.02em; }
.card p { color: var(--slate-500); font-size: 0.9rem; line-height: 1.6; }
.card-link { text-decoration: none; color: inherit; transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1); }

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 2rem; padding: 4rem 0; }

.btn { display: inline-flex; align-items: center; justify-content: center; padding: 0.85rem 2.25rem; border-radius: 0.75rem; font-weight: 700; cursor: pointer; transition: all 0.2s; border: none; font-size: 1rem; gap: 0.5rem; }
.btn-primary { background: var(--primary); color: white; box-shadow: 0 4px 14px 0 rgba(79, 70, 229, 0.39); }
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-2px); box-shadow: 0 6px 20px rgba(79, 70, 229, 0.4); }
.btn-outline { background: var(--white); border: 2px solid var(--slate-200); color: var(--slate-700); }
.btn-outline:hover { background: var(--slate-50); border-color: var(--slate-300); }
.btn-full { width: 100%; }

/* Forms */
.form-group { margin-bottom: 1.5rem; }
label { display: block; font-size: 0.85rem; font-weight: 700; color: var(--slate-700); margin-bottom: 0.5rem; text-transform: uppercase; letter-spacing: 0.05em; }
input, select { width: 100%; padding: 0.85rem 1.15rem; border-radius: 0.75rem; border: 2px solid var(--slate-200); font-size: 1rem; outline: none; transition: all 0.2s; font-family: inherit; }
input:focus { border-color: var(--primary); box-shadow: 0 0 0 4px var(--indigo-50); }

/* Results */
.result-box { margin-top: 2rem; padding: 2.5rem; background: var(--indigo-50); border: 2px solid var(--indigo-100); border-radius: var(--radius-xl); animation: slideUp 0.4s ease-out; }
@keyframes slideUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
.result-value { font-size: 3.5rem; font-weight: 900; color: var(--primary); letter-spacing: -0.06em; line-height: 1; }
.result-sub { font-size: 0.75rem; color: var(--slate-500); text-transform: uppercase; font-weight: 800; margin-top: 0.5rem; letter-spacing: 0.1em; }

/* Article */
.article { margin-top: 4rem; padding-top: 4rem; border-top: 2px solid var(--slate-100); }
.article h2 { font-size: 1.75rem; font-weight: 900; margin-bottom: 1.5rem; letter-spacing: -0.04em; }
.article h3 { font-size: 1.5rem; font-weight: 800; margin: 2.5rem 0 1rem; color: var(--slate-800); }
.article p { color: var(--slate-600); margin-bottom: 1.5rem; font-size: 1.1rem; }
.article ul { margin-bottom: 1.5rem; padding-left: 1.5rem; color: var(--slate-600); }
.article li { margin-bottom: 0.75rem; }

/* Footer */
footer { background: var(--white); border-top: 1px solid var(--slate-200); padding: 5rem 0; margin-top: 5rem; }
.footer-grid { display: flex; justify-content: space-around; }
.footer-links { list-style-type: none;}
.footer-links li a { text-decoration: none; color: inherit}

@media (max-width: 768px) {
  .hero h1 { font-size: 2.75rem; }
  .grid { grid-template-columns: 1fr; }
  .footer-grid { flex-direction: column; align-items: center; gap: 3rem;}
  .nav-links { display: none; }
}