:root{
  --primary:#171717; --bg:#ffffff; --text:#171717; --text-light:#666666;
  --accent:#0070f3; --bg-soft:#fafafa; --border:#eaeaea;
  --radius:6px; --shadow:0 1px 3px rgba(0,0,0,0.08);
  --font:'Inter',-apple-system,'Segoe UI',sans-serif; --max:900px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--font);color:var(--text);background:var(--bg);line-height:1.6;-webkit-font-smoothing:antialiased}
.container{max-width:var(--max);margin:0 auto;padding:0 24px}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}

header{border-bottom:1px solid var(--border);padding:18px 0;background:var(--bg)}
.header-inner{display:flex;align-items:center;justify-content:space-between}
.logo{font-weight:700;font-size:1.1rem;color:var(--text)}
.logo span{color:var(--accent)}

.hero{padding:56px 0 32px;text-align:center}
.hero h1{font-size:2.1rem;font-weight:800;letter-spacing:-0.03em;line-height:1.2;margin-bottom:14px}
.hero p{font-size:1.08rem;color:var(--text-light);max-width:620px;margin:0 auto}

.calc-section{padding:8px 0 40px}
.calc-card{background:var(--bg);border:1px solid var(--border);border-radius:12px;box-shadow:var(--shadow);overflow:hidden}
.calc-grid{display:grid;grid-template-columns:1fr 1fr;gap:0}
@media(max-width:720px){.calc-grid{grid-template-columns:1fr}}

.calc-inputs{padding:28px}
.calc-inputs h2{font-size:1.15rem;font-weight:700;margin-bottom:20px}
.field{margin-bottom:16px}
.field label{display:block;font-size:0.85rem;font-weight:600;color:var(--text-light);margin-bottom:6px}
.field input,.field select{width:100%;padding:10px 12px;border:1px solid var(--border);border-radius:var(--radius);font-size:1rem;font-family:var(--font);color:var(--text);background:var(--bg)}
.field input:focus,.field select:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px rgba(0,112,243,0.12)}
.field-row{display:grid;grid-template-columns:1fr 1fr;gap:12px}
@media(max-width:480px){.field-row{grid-template-columns:1fr}}
.input-suffix{position:relative}
.input-suffix input{padding-right:34px}
.input-suffix .suffix{position:absolute;right:12px;top:50%;transform:translateY(-50%);font-size:0.85rem;color:var(--text-light);pointer-events:none}

.calc-results{background:var(--bg-soft);padding:28px;border-left:1px solid var(--border)}
@media(max-width:720px){.calc-results{border-left:none;border-top:1px solid var(--border)}}
.calc-results h2{font-size:1.15rem;font-weight:700;margin-bottom:20px}
.result-row{display:flex;justify-content:space-between;align-items:center;padding:14px 0;border-bottom:1px solid var(--border)}
.result-row:last-child{border-bottom:none}
.result-label{font-size:0.9rem;color:var(--text-light)}
.result-value{font-size:1.15rem;font-weight:700;text-align:right}
.result-value small{display:block;font-size:0.75rem;font-weight:400;color:var(--text-light)}
.result-row.highlight{background:var(--bg);margin:12px -16px;padding:16px;border:1px solid var(--border);border-radius:var(--radius)}
.result-row.highlight .result-value{color:var(--accent);font-size:1.4rem}
.result-total{margin-top:12px;font-size:0.8rem;color:var(--text-light);text-align:right}

.explain{padding:40px 0}
.explain h2{font-size:1.5rem;font-weight:800;letter-spacing:-0.02em;margin-bottom:20px}
.explain-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px}
@media(max-width:640px){.explain-grid{grid-template-columns:1fr}}
.explain-card{background:var(--bg-soft);border:1px solid var(--border);border-radius:var(--radius);padding:20px}
.explain-card h3{font-size:1rem;font-weight:700;margin-bottom:8px}
.explain-card p{font-size:0.9rem;color:var(--text-light)}
.explain-card code{background:var(--bg);border:1px solid var(--border);border-radius:4px;padding:2px 6px;font-size:0.82rem}

.faq{padding:24px 0 48px}
.faq h2{font-size:1.5rem;font-weight:800;letter-spacing:-0.02em;margin-bottom:20px}
.faq-item{border:1px solid var(--border);border-radius:var(--radius);margin-bottom:12px;overflow:hidden}
.faq-item summary{padding:16px 20px;font-weight:600;cursor:pointer;font-size:0.95rem}
.faq-item summary:hover{background:var(--bg-soft)}
.faq-item .faq-a{padding:0 20px 16px;font-size:0.9rem;color:var(--text-light)}

footer{border-top:1px solid var(--border);padding:32px 0;margin-top:24px}
.footer-inner{display:flex;flex-wrap:wrap;justify-content:space-between;gap:16px;font-size:0.82rem;color:var(--text-light)}
.disclaimer{font-size:0.78rem;color:var(--text-light);max-width:700px;margin-top:16px}

@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{transition:none!important;animation:none!important}}