@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

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

body{font-family:'Inter',system-ui,sans-serif;background:#0f0f13;color:#e4e4e7;line-height:1.6;min-height:100vh}

.container{max-width:900px;margin:0 auto;padding:0 1.25rem}

/* Header */
.site-header{border-bottom:1px solid rgba(255,255,255,0.06);padding:1rem 0}
.site-header .container{display:flex;align-items:center;justify-content:space-between}
.logo{display:flex;align-items:center;gap:0.5rem;text-decoration:none;color:#e4e4e7;font-weight:700;font-size:1.15rem}
.logo-icon{font-size:1.4rem;background:linear-gradient(135deg,#818cf8,#6366f1,#4f46e5);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;font-weight:800}
.site-header nav{display:flex;gap:1.5rem}
.site-header nav a{color:#a1a1aa;text-decoration:none;font-size:0.9rem;font-weight:500;transition:color 0.2s}
.site-header nav a:hover{color:#e4e4e7}

/* Hero */
.hero{text-align:center;padding:3rem 1.25rem 1.5rem}
.hero h1{font-size:2.5rem;font-weight:800;background:linear-gradient(135deg,#818cf8,#6366f1,#4f46e5);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;margin-bottom:0.5rem}
.hero p{color:#a1a1aa;font-size:1.05rem;max-width:550px;margin:0 auto}

/* Card */
.card{background:#1a1a2e;border:1px solid rgba(255,255,255,0.06);border-radius:1.25rem;padding:1.75rem;margin-bottom:1.5rem}

/* Category tabs */
.category-tabs{display:flex;flex-wrap:wrap;gap:0.4rem;margin-bottom:1.5rem}
.cat-tab{background:rgba(255,255,255,0.06);border:1px solid rgba(255,255,255,0.08);color:#a1a1aa;padding:0.4rem 0.9rem;border-radius:2rem;font-size:0.82rem;cursor:pointer;font-family:'Inter',sans-serif;font-weight:500;transition:all 0.2s}
.cat-tab:hover{background:rgba(99,102,241,0.1);color:#c7d2fe}
.cat-tab.active{background:rgba(99,102,241,0.18);border-color:rgba(99,102,241,0.4);color:#a5b4fc}

/* Converter area */
.converter-row{display:grid;grid-template-columns:1fr auto 1fr;gap:1rem;align-items:end}
.converter-col label{display:block;font-weight:600;font-size:0.85rem;margin-bottom:0.4rem;color:#a1a1aa}
.converter-col select{width:100%;background:#0f0f13;border:1px solid rgba(255,255,255,0.1);border-radius:0.75rem;padding:0.7rem 1rem;color:#e4e4e7;font-family:'Inter',sans-serif;font-size:0.9rem;appearance:none;cursor:pointer;margin-bottom:0.5rem}
.converter-col select:focus{outline:none;border-color:#6366f1}
.converter-col input[type="number"]{width:100%;background:#0f0f13;border:1px solid rgba(255,255,255,0.1);border-radius:0.75rem;padding:0.75rem 1rem;color:#e4e4e7;font-family:'JetBrains Mono',monospace;font-size:1.15rem;font-weight:600}
.converter-col input[type="number"]:focus{outline:none;border-color:#6366f1}

.swap-col{display:flex;align-items:center;justify-content:center;padding-bottom:0.25rem}
.btn-swap{background:rgba(99,102,241,0.12);border:1px solid rgba(99,102,241,0.25);color:#a5b4fc;width:44px;height:44px;border-radius:50%;font-size:1.3rem;cursor:pointer;transition:all 0.2s;display:flex;align-items:center;justify-content:center;font-family:'Inter',sans-serif}
.btn-swap:hover{background:rgba(99,102,241,0.25);border-color:rgba(99,102,241,0.5)}

/* Result */
.result-box{margin-top:1.25rem;background:rgba(99,102,241,0.06);border:1px solid rgba(99,102,241,0.15);border-radius:1rem;padding:1.25rem;text-align:center}
.result-value{font-size:1.8rem;font-weight:800;color:#a5b4fc;font-family:'JetBrains Mono',monospace;word-break:break-all}
.result-label{font-size:0.85rem;color:#71717a;margin-top:0.25rem}
.result-formula{margin-top:0.75rem;font-size:0.82rem;color:#71717a;font-family:'JetBrains Mono',monospace;background:rgba(0,0,0,0.2);padding:0.5rem 0.75rem;border-radius:0.5rem;display:inline-block}

/* Content sections */
.content-section h2{font-size:1.5rem;font-weight:700;margin-bottom:1rem;color:#f4f4f5}
.content-section h3{font-size:1.1rem;font-weight:600;margin:1.25rem 0 0.5rem;color:#d4d4d8}
.content-section p{color:#a1a1aa;margin-bottom:0.75rem;font-size:0.95rem}
.content-section ul{list-style:disc;padding-left:1.5rem;color:#a1a1aa;margin-bottom:1rem}
.content-section ul li{margin-bottom:0.35rem;font-size:0.95rem}
.content-section details{background:rgba(255,255,255,0.03);border:1px solid rgba(255,255,255,0.06);border-radius:0.75rem;padding:1rem;margin-bottom:0.5rem}
.content-section summary{font-weight:600;cursor:pointer;color:#d4d4d8}
.content-section details p{margin-top:0.5rem;margin-bottom:0}

/* Ad slots */
.ad-slot{min-height:90px;margin:1.5rem auto;text-align:center;max-width:728px}

/* Footer */
.site-footer{border-top:1px solid rgba(255,255,255,0.06);padding:2rem 0;margin-top:3rem}
.site-footer .container{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:1rem}
.site-footer p{color:#71717a;font-size:0.85rem}
.site-footer nav{display:flex;gap:1.5rem}
.site-footer nav a{color:#71717a;text-decoration:none;font-size:0.85rem;transition:color 0.2s}
.site-footer nav a:hover{color:#a1a1aa}

.hidden{display:none !important}

@media(max-width:640px){
    .hero h1{font-size:1.75rem}
    .site-header nav{display:none}
    .converter-row{grid-template-columns:1fr;gap:0.75rem}
    .swap-col{padding:0}
    .btn-swap{transform:rotate(90deg)}
    .card{padding:1.25rem}
    .site-footer .container{flex-direction:column;text-align:center}
    .category-tabs{justify-content:center}
}