:root{
  --bg:#f6f7fb;
  --surface:#ffffff;
  --surface-2:#f0f1f6;
  --border:#e3e5ec;
  --text:#1b1e29;
  --text-muted:#666b7d;
  --primary:#4f5bd5;
  --primary-hover:#3f49b8;
  --primary-soft:#eef0fd;
  --accent:#1a9c7f;
  --danger:#d64545;
  --radius:14px;
  --shadow:0 1px 2px rgba(20,22,40,.04), 0 8px 24px rgba(20,22,40,.05);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
}
@media (prefers-color-scheme: dark){
  :root{
    --bg:#14151c;
    --surface:#1b1d27;
    --surface-2:#22242f;
    --border:#2c2f3d;
    --text:#eceef4;
    --text-muted:#9497a8;
    --primary:#818cf8;
    --primary-hover:#9aa3fa;
    --primary-soft:#252949;
    --accent:#34d399;
    --danger:#f16565;
    --shadow:0 1px 2px rgba(0,0,0,.3), 0 8px 24px rgba(0,0,0,.35);
  }
}
*{box-sizing:border-box;}
body{margin:0;background:var(--bg);color:var(--text);}
a{color:inherit;}
.app{display:flex;min-height:100vh;}

/* Sidebar */
.sidebar{
  width:260px;flex-shrink:0;background:var(--surface);border-right:1px solid var(--border);
  padding:20px 14px;position:sticky;top:0;height:100vh;overflow-y:auto;
}
.brand{display:flex;align-items:center;gap:10px;padding:4px 8px 18px;text-decoration:none;}
.brand-mark{
  width:34px;height:34px;border-radius:10px;background:linear-gradient(135deg,var(--primary),var(--accent));
  display:flex;align-items:center;justify-content:center;color:#fff;font-weight:700;font-size:16px;flex-shrink:0;
}
.brand-text{font-weight:700;font-size:14.5px;letter-spacing:-.01em;color:var(--text);white-space:nowrap;}
.search-box{
  width:100%;padding:9px 12px;border-radius:10px;border:1px solid var(--border);background:var(--surface-2);
  color:var(--text);font-size:13.5px;margin-bottom:14px;outline:none;
}
.search-box:focus{border-color:var(--primary);}
.nav-group-title{
  font-size:11px;text-transform:uppercase;letter-spacing:.06em;color:var(--text-muted);
  padding:14px 10px 6px;font-weight:600;
}
.nav-item{
  display:flex;align-items:center;gap:10px;padding:8px 10px;border-radius:9px;cursor:pointer;
  font-size:13.5px;color:var(--text);text-decoration:none;
}
.nav-item:hover{background:var(--surface-2);}
.nav-item.active{background:var(--primary-soft);color:var(--primary);font-weight:600;}
.nav-icon{font-size:15px;width:18px;text-align:center;flex-shrink:0;}

/* Main */
.content{flex:1;padding:32px 40px;max-width:920px;}
.content-inner{max-width:720px;}
h1.page-title{font-size:24px;margin:0 0 8px;}
p.page-sub{color:var(--text-muted);margin:0 0 20px;font-size:14px;}
p.lead{font-size:15px;color:var(--text-muted);line-height:1.65;margin:0 0 22px;max-width:660px;}

.home-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;margin-top:8px;}
.tool-card{
  background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);
  padding:16px;cursor:pointer;box-shadow:var(--shadow);transition:transform .12s ease, border-color .12s ease;
  display:block;text-decoration:none;color:inherit;
}
.tool-card:hover{border-color:var(--primary);transform:translateY(-2px);}
.tool-card .icon{font-size:22px;margin-bottom:8px;display:block;}
.tool-card .name{font-weight:600;font-size:14px;margin-bottom:3px;color:var(--text);}
.tool-card .desc{font-size:12.5px;color:var(--text-muted);line-height:1.4;}

.category-block{margin-bottom:30px;}
.category-heading{font-size:13px;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:.05em;margin:0 0 12px;}

.panel{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:26px;box-shadow:var(--shadow);}
.breadcrumb{font-size:12.5px;color:var(--text-muted);margin-bottom:14px;}
.breadcrumb a{color:var(--text-muted);text-decoration:none;}
.breadcrumb a:hover{color:var(--primary);}

label{display:block;font-size:12.5px;color:var(--text-muted);margin:14px 0 5px;font-weight:600;}
label:first-of-type{margin-top:0;}
input[type=text],input[type=number],input[type=date],select,textarea{
  width:100%;padding:9px 11px;border-radius:9px;border:1px solid var(--border);background:var(--surface-2);
  color:var(--text);font-size:14px;outline:none;font-family:inherit;
}
input:focus,select:focus,textarea:focus{border-color:var(--primary);}
textarea{resize:vertical;min-height:90px;}
.row{display:flex;gap:12px;}
.row > div{flex:1;}
.btn{
  background:var(--primary);color:#fff;border:none;padding:10px 18px;border-radius:9px;font-size:14px;font-weight:600;
  cursor:pointer;margin-top:16px;
}
.btn:hover{background:var(--primary-hover);}
.btn.secondary{background:var(--surface-2);color:var(--text);border:1px solid var(--border);}
.btn.secondary:hover{background:var(--border);}
.btn-row{display:flex;gap:10px;flex-wrap:wrap;}
.result-box{
  margin-top:18px;padding:14px 16px;background:var(--surface-2);border-radius:10px;border:1px solid var(--border);
  font-size:14px;word-break:break-all;
}
.result-box .big{font-size:22px;font-weight:700;color:var(--primary);}
.muted{color:var(--text-muted);font-size:12.5px;}
.copy-btn{font-size:11.5px;color:var(--primary);cursor:pointer;font-weight:600;margin-left:8px;}
.chip-row{display:flex;flex-wrap:wrap;gap:8px;margin-top:10px;}
.chip{
  padding:6px 12px;border-radius:20px;border:1px solid var(--border);font-size:12.5px;cursor:pointer;
  background:var(--surface-2);
}
.chip.active{background:var(--primary);color:#fff;border-color:var(--primary);}
.swatch{width:100%;height:70px;border-radius:10px;border:1px solid var(--border);margin-top:12px;}
.calc-display{
  background:var(--surface-2);border-radius:10px;padding:16px;text-align:right;font-size:28px;font-weight:600;
  margin-bottom:12px;overflow-x:auto;white-space:nowrap;border:1px solid var(--border);
}
.calc-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;}
.calc-btn{
  padding:16px 0;border-radius:9px;border:1px solid var(--border);background:var(--surface-2);font-size:16px;
  cursor:pointer;font-weight:600;
}
.calc-btn:hover{background:var(--border);}
.calc-btn.op{background:var(--primary-soft);color:var(--primary);}
.calc-btn.eq{background:var(--primary);color:#fff;}
.timer-display{font-size:52px;font-weight:700;text-align:center;padding:24px 0;letter-spacing:.02em;}
#qr-canvas-holder{margin-top:14px;padding:16px;background:#fff;border-radius:10px;display:inline-block;}
::placeholder{color:var(--text-muted);opacity:.7;}
code.pre{
  display:block;white-space:pre-wrap;word-break:break-all;background:var(--surface-2);border:1px solid var(--border);
  border-radius:10px;padding:12px;font-size:13px;margin-top:10px;
}
table.strength-table{width:100%;border-collapse:collapse;margin-top:10px;font-size:13px;}
table.strength-table td,table.strength-table th{padding:6px 4px;border-bottom:1px solid var(--border);text-align:left;}

/* SERP snippet preview */
.serp-preview{
  margin-top:10px;padding:16px 18px;background:var(--surface);border:1px solid var(--border);border-radius:10px;
  font-family:Arial,sans-serif;
}
.serp-url{color:#1a1a1a;font-size:13px;margin-bottom:2px;}
@media (prefers-color-scheme: dark){ .serp-url{ color:#c5c9d6; } }
.serp-title{color:#1a0dab;font-size:19px;line-height:1.3;margin-bottom:3px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;}
@media (prefers-color-scheme: dark){ .serp-title{ color:#8ab4f8; } }
.serp-desc{color:#4d5156;font-size:13.5px;line-height:1.45;}
@media (prefers-color-scheme: dark){ .serp-desc{ color:#bdc1c6; } }

/* SEO content blocks */
.seo-content{margin-top:36px;max-width:680px;}
.seo-content h2{font-size:17px;margin:26px 0 10px;}
.seo-content p{font-size:14px;line-height:1.75;color:var(--text);}
.faq details{
  border:1px solid var(--border);border-radius:10px;padding:12px 16px;margin-bottom:10px;background:var(--surface);
}
.faq summary{cursor:pointer;font-weight:600;font-size:14px;list-style:none;}
.faq summary::-webkit-details-marker{display:none;}
.faq summary::before{content:'+ ';color:var(--primary);font-weight:700;}
.faq details[open] summary::before{content:'– ';}
.faq p{margin:10px 0 0;font-size:13.5px;color:var(--text-muted);line-height:1.65;}
.related-tools{margin-top:40px;}
.related-tools h2{font-size:15px;color:var(--text-muted);text-transform:uppercase;letter-spacing:.05em;margin:0 0 14px;}
footer.site-footer{
  margin-top:56px;padding-top:20px;border-top:1px solid var(--border);color:var(--text-muted);
  font-size:12px;text-align:center;
}
footer.site-footer a{color:var(--text-muted);}
.footer-note{margin-top:36px;color:var(--text-muted);font-size:12px;text-align:center;}

/* Mobile navigation */
.mobile-topbar{
  display:none;
  align-items:center;
  gap:12px;
  padding:12px 16px;
  background:var(--surface);
  border-bottom:1px solid var(--border);
  position:sticky;
  top:0;
  z-index:20;
}
.hamburger-btn{
  width:38px;height:38px;border-radius:9px;border:1px solid var(--border);background:var(--surface-2);
  font-size:18px;cursor:pointer;color:var(--text);display:flex;align-items:center;justify-content:center;flex-shrink:0;
  padding:0;
}
.sidebar-overlay{
  display:none;position:fixed;inset:0;background:rgba(15,17,24,.45);z-index:29;
}
.sidebar-overlay.show{display:block;}

@media (max-width:760px){
  .app{flex-direction:column;}
  .mobile-topbar{display:flex;}
  .sidebar{
    position:fixed;top:0;left:0;height:100vh;width:82%;max-width:300px;z-index:30;
    transform:translateX(-100%);transition:transform .22s ease;box-shadow:0 0 24px rgba(0,0,0,.25);
  }
  .sidebar.open{transform:translateX(0);}
  .sidebar .brand{display:none;}
  .content{padding:18px;}
  h1.page-title{font-size:21px;}
}

@media (max-width:480px){
  .row{flex-direction:column;}
  .home-grid{grid-template-columns:repeat(2,1fr);gap:10px;}
  .content{padding:14px;}
  .panel{padding:18px;}
  .calc-btn{padding:14px 0;font-size:15px;}
  .btn,.btn.secondary{width:100%;}
  .btn-row{flex-direction:column;}
}

@media (max-width:360px){
  .home-grid{grid-template-columns:1fr;}
}