:root{
  --bg:#ffffff; --ink:#1a1a1a; --muted:#6b7280; --line:#e5e7eb;
  --brand:#0d9488; --brand-dark:#0f766e; --soft:#f0fdfa; --radius:14px;
}
*{box-sizing:border-box;margin:0;padding:0}
body{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;color:var(--ink);background:var(--bg);line-height:1.75;-webkit-font-smoothing:antialiased}
.wrap{max-width:1080px;margin:0 auto;padding:0 20px}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}

/* nav */
.nav{position:sticky;top:0;background:rgba(255,255,255,.94);backdrop-filter:blur(8px);border-bottom:1px solid var(--line);z-index:50}
.nav-inner{display:flex;align-items:center;justify-content:space-between;height:60px}
.logo{font-weight:800;font-size:20px;color:var(--ink)}
.logo span{color:var(--brand)}
.menu{display:flex;gap:20px}
.menu a{color:var(--muted);font-size:15px}
.menu a.active,.menu a:hover{color:var(--ink);text-decoration:none}

/* hero */
.hero{background:linear-gradient(135deg,#f0fdfa 0%,#f8fafc 60%,#eff6ff 100%);padding:64px 0 56px;text-align:center}
.hero-kicker{display:inline-block;font-size:13px;color:var(--brand);background:#ccfbf1;border-radius:999px;padding:4px 14px;margin-bottom:16px;font-weight:600}
.hero h1{font-size:38px;line-height:1.3;margin-bottom:12px}
.hero-sub{color:var(--muted);font-size:16.5px;max-width:640px;margin:0 auto}
.privacy{display:inline-flex;align-items:center;gap:6px;margin-top:18px;font-size:13.5px;color:var(--brand-dark);background:#fff;border:1px solid #99f6e4;border-radius:999px;padding:6px 16px}

/* tool grid */
.section{padding:52px 0 8px}
.section-title{font-size:25px;margin-bottom:6px}
.section-desc{color:var(--muted);margin-bottom:26px}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.tool-card{border:1px solid var(--line);border-radius:var(--radius);padding:26px 22px;color:var(--ink);transition:.2s;display:block;background:#fff}
.tool-card:hover{box-shadow:0 12px 30px rgba(13,148,136,.12);text-decoration:none;transform:translateY(-2px)}
.tool-card .icon{font-size:34px;display:block;margin-bottom:12px}
.tool-card h3{font-size:17px;margin-bottom:6px}
.tool-card p{font-size:13.5px;color:var(--muted)}

/* tool page */
.tool-page{max-width:820px;margin:0 auto;padding:44px 20px 20px}
.tool-page h1{font-size:30px;margin-bottom:8px}
.tool-page .lede{color:var(--muted);margin-bottom:26px}
.panel{border:1px solid var(--line);border-radius:var(--radius);padding:28px;background:#fff;margin-bottom:20px}
.drop{border:2px dashed #99f6e4;border-radius:12px;padding:40px 20px;text-align:center;color:var(--muted);cursor:pointer;transition:.2s;background:var(--soft)}
.drop:hover{border-color:var(--brand);color:var(--brand-dark)}
.drop input{display:none}
.row{display:flex;gap:14px;flex-wrap:wrap;align-items:center;margin:16px 0}
.row label{font-size:14px;color:#374151;min-width:90px}
input[type=range]{flex:1;min-width:160px}
input[type=text],input[type=number],select,textarea{border:1px solid var(--line);border-radius:8px;padding:10px 12px;font-size:14.5px;font-family:inherit;width:100%}
textarea{min-height:140px;resize:vertical;font-family:ui-monospace,Menlo,Consolas,monospace}
.btn{display:inline-block;padding:11px 26px;border-radius:999px;font-weight:600;font-size:15px;border:1px solid transparent;cursor:pointer;transition:.2s;background:var(--brand);color:#fff}
.btn:hover{background:var(--brand-dark);text-decoration:none}
.btn-ghost{background:#fff;color:var(--ink);border-color:var(--line)}
.btn-ghost:hover{border-color:var(--brand);color:var(--brand-dark)}
.btn:disabled{opacity:.5;cursor:not-allowed}
.result{display:none;margin-top:20px;border-top:1px solid var(--line);padding-top:20px}
.result.show{display:block}
.stat{display:flex;gap:24px;flex-wrap:wrap;margin:14px 0;font-size:14.5px}
.stat b{color:var(--brand-dark)}
.preview{max-width:100%;border-radius:8px;border:1px solid var(--line);margin-top:10px}
.hint{font-size:13px;color:var(--muted);margin-top:10px}
.error{color:#dc2626;font-size:14px;margin-top:10px}
.success{color:var(--brand-dark);font-size:14px;margin-top:10px}
.checkbox-row{display:flex;gap:18px;flex-wrap:wrap;font-size:14.5px;color:#374151}
.checkbox-row label{display:flex;align-items:center;gap:6px;cursor:pointer;min-width:0}
.output{font-family:ui-monospace,Menlo,Consolas,monospace;background:var(--soft);border-radius:8px;padding:14px;word-break:break-all;font-size:15px;margin-top:12px}

/* howto + faq */
.howto h2,.faq h2{font-size:21px;margin:34px 0 12px}
.howto ol{margin-left:22px;color:#374151}
.howto li{margin-bottom:8px}
.faq details{border:1px solid var(--line);border-radius:12px;padding:14px 18px;margin-bottom:10px;background:var(--soft)}
.faq summary{font-weight:600;cursor:pointer}
.faq p{margin-top:8px;color:#4b5563;font-size:14.5px}

/* ads */
.ad-slot{margin:24px auto;text-align:center;min-height:90px;display:flex;align-items:center;justify-content:center;background:#fafafa;border:1px dashed var(--line);border-radius:8px;color:#cbd5e1;font-size:12px;max-width:970px}
.ad-slot.filled{background:none;border:none;min-height:0}

/* article */
.article{max-width:760px;margin:0 auto;padding:44px 20px 20px}
.article h1{font-size:30px;line-height:1.4;margin-bottom:10px}
.article .meta{color:var(--muted);font-size:14px;margin-bottom:24px}
.article h2{font-size:22px;margin:32px 0 12px}
.article p{margin-bottom:14px;color:#374151}
.article ul,.article ol{margin:0 0 16px 22px;color:#374151}
.article li{margin-bottom:8px}
.back{display:inline-block;margin-bottom:8px;font-size:14px}

/* footer */
.footer{margin-top:60px;border-top:1px solid var(--line);background:var(--soft);padding:30px 0}
.footer p{font-size:13px;color:var(--muted);margin-bottom:6px}
.copyright{text-align:center;margin-top:14px}

@media(max-width:820px){
  .grid{grid-template-columns:1fr 1fr}
  .hero h1{font-size:28px}
}
@media(max-width:520px){.grid{grid-template-columns:1fr}}