:root {
  --bg: #0c0f14;
  --bg2: #12161e;
  --card: #181d28;
  --card-hover: #1e2433;
  --border: #2a3040;
  --fg: #e8ecf4;
  --fg-muted: #7a8499;
  --accent: #f0a500;
  --accent-dim: rgba(240,165,0,0.12);
  --accent-glow: rgba(240,165,0,0.25);
  --success: #34d399;
  --danger: #f87171;
  --info: #60a5fa;
  --radius: 14px;
  --radius-sm: 8px;
}

* { margin:0; padding:0; box-sizing:border-box; }
html { scroll-behavior: smooth; }

body {
  font-family: 'Space Grotesk', sans-serif;
  background: var(--bg);
  color: var(--fg);
  min-height: 100vh;
  overflow-x: hidden;
  line-height: 1.7;
}

/* Background */
.bg-scene { position:fixed; inset:0; z-index:0; pointer-events:none; overflow:hidden; }
.bg-blob { position:absolute; border-radius:50%; filter:blur(120px); opacity:0.3; animation:blobFloat 18s ease-in-out infinite alternate; }
.bg-blob:nth-child(1) { width:500px; height:500px; background:var(--accent); top:-10%; left:-10%; animation-duration:20s; }
.bg-blob:nth-child(2) { width:400px; height:400px; background:#e04e6a; bottom:-15%; right:-10%; animation-duration:24s; animation-delay:-5s; }
.bg-blob:nth-child(3) { width:300px; height:300px; background:#6366f1; top:50%; left:50%; transform:translate(-50%,-50%); animation-duration:22s; animation-delay:-10s; }
@keyframes blobFloat {
  0% { transform:translate(0,0) scale(1); }
  33% { transform:translate(40px,-30px) scale(1.1); }
  66% { transform:translate(-20px,40px) scale(0.95); }
  100% { transform:translate(30px,20px) scale(1.05); }
}
.bg-grid { position:fixed; inset:0; z-index:0; pointer-events:none; background-image:linear-gradient(rgba(240,165,0,0.03) 1px,transparent 1px),linear-gradient(90deg,rgba(240,165,0,0.03) 1px,transparent 1px); background-size:60px 60px; }

.app-wrapper { position:relative; z-index:1; min-height:100vh; display:flex; flex-direction:column; }

/* Header */
header {
  padding: 14px 24px;
  display:flex; align-items:center; justify-content:space-between;
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(20px);
  background: rgba(12,15,20,0.75);
  position:sticky; top:0; z-index:100;
}
.logo { display:flex; align-items:center; gap:10px; font-size:1.3rem; font-weight:700; text-decoration:none; color:var(--fg); }
.logo-icon { width:36px; height:36px; background:linear-gradient(135deg,var(--accent),#e04e6a); border-radius:10px; display:grid; place-items:center; font-size:1rem; color:#000; font-weight:700; }
.logo span { color:var(--accent); }

nav { display:flex; gap:4px; align-items:center; flex-wrap:wrap; }
nav a {
  color:var(--fg-muted); padding:7px 14px; border-radius:var(--radius-sm);
  text-decoration:none; font-size:0.84rem; font-weight:500; transition:all 0.25s;
  border:1px solid transparent; white-space:nowrap;
}
nav a:hover { color:var(--fg); background:var(--accent-dim); border-color:rgba(240,165,0,0.2); }
nav a.active { color:var(--accent); background:var(--accent-dim); border-color:rgba(240,165,0,0.3); }

/* Main */
main { flex:1; padding:28px 24px 60px; max-width:1100px; margin:0 auto; width:100%; }

/* Hero */
.hero { text-align:center; padding:36px 0 30px; }
.hero h1 { font-size:clamp(1.8rem,5vw,3rem); font-weight:700; line-height:1.15; letter-spacing:-1.5px; margin-bottom:12px; }
.hero h1 span { color:var(--accent); }
.hero p { color:var(--fg-muted); font-size:1rem; max-width:580px; margin:0 auto; }

/* Grid */
.calc-grid { display:grid; grid-template-columns:repeat(auto-fill,minmax(300px,1fr)); gap:16px; margin-top:28px; }
.calc-card {
  background:var(--card); border:1px solid var(--border); border-radius:var(--radius);
  padding:24px; transition:all 0.3s; position:relative; overflow:hidden;
}
.calc-card::before { content:''; position:absolute; top:0; left:0; right:0; height:3px; background:linear-gradient(90deg,var(--accent),#e04e6a); opacity:0; transition:opacity 0.3s; }
.calc-card:hover { border-color:rgba(240,165,0,0.4); transform:translateY(-3px); box-shadow:0 10px 35px rgba(0,0,0,0.3); }
.calc-card:hover::before { opacity:1; }
.calc-card h3 { font-size:1.05rem; font-weight:600; margin-bottom:4px; }
.calc-card p { color:var(--fg-muted); font-size:0.83rem; line-height:1.5; }
.calc-card-icon { width:44px; height:44px; border-radius:11px; display:grid; place-items:center; font-size:1.1rem; margin-bottom:14px; }

/* Calculator Panel */
.calc-panel { background:var(--card); border:1px solid var(--border); border-radius:var(--radius); overflow:hidden; max-width:540px; margin:0 auto; }
.calc-panel-header { padding:16px 22px; border-bottom:1px solid var(--border); display:flex; align-items:center; justify-content:space-between; }
.calc-panel-header h2 { font-size:1.1rem; font-weight:600; }
.back-link { color:var(--accent); text-decoration:none; font-size:0.82rem; font-weight:500; display:flex; align-items:center; gap:5px; }
.back-link:hover { text-decoration:underline; }
.calc-panel-body { padding:22px; }

/* Display */
.calc-display { background:var(--bg); border:1px solid var(--border); border-radius:12px; padding:16px 18px; margin-bottom:16px; text-align:right; min-height:85px; display:flex; flex-direction:column; justify-content:flex-end; }
.calc-display .expr { font-family:'JetBrains Mono',monospace; color:var(--fg-muted); font-size:0.82rem; min-height:18px; word-break:break-all; }
.calc-display .result { font-family:'JetBrains Mono',monospace; font-size:1.9rem; font-weight:700; color:var(--fg); word-break:break-all; line-height:1.2; }

/* Buttons */
.btn-grid { display:grid; gap:7px; }
.btn-grid.grid-4 { grid-template-columns:repeat(4,1fr); }
.btn-grid.grid-5 { grid-template-columns:repeat(5,1fr); }
.btn-grid.grid-6 { grid-template-columns:repeat(6,1fr); }
.calc-btn {
  padding:13px 8px; border:1px solid var(--border); border-radius:10px; background:var(--bg2);
  color:var(--fg); font-family:'JetBrains Mono',monospace; font-size:0.95rem; font-weight:500;
  cursor:pointer; transition:all 0.15s; user-select:none;
}
.calc-btn:hover { background:var(--card-hover); border-color:rgba(240,165,0,0.3); }
.calc-btn:active { transform:scale(0.95); }
.calc-btn.op { color:var(--accent); font-weight:600; }
.calc-btn.accent { background:linear-gradient(135deg,var(--accent),#d4900a); color:#000; border-color:transparent; font-weight:700; }
.calc-btn.accent:hover { filter:brightness(1.1); }
.calc-btn.danger { color:var(--danger); }
.calc-btn.small { font-size:0.78rem; padding:10px 5px; }

/* Forms */
.form-group { margin-bottom:14px; }
.form-group label { display:block; font-size:0.78rem; font-weight:500; color:var(--fg-muted); margin-bottom:5px; text-transform:uppercase; letter-spacing:0.5px; }
.form-input {
  width:100%; padding:11px 13px; background:var(--bg); border:1px solid var(--border);
  border-radius:var(--radius-sm); color:var(--fg); font-family:'JetBrains Mono',monospace;
  font-size:0.92rem; outline:none; transition:border-color 0.2s;
}
.form-input:focus { border-color:var(--accent); box-shadow:0 0 0 3px var(--accent-dim); }
.form-input::placeholder { color:var(--fg-muted); opacity:0.5; }
select.form-input { appearance:none; background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%237a8499' viewBox='0 0 16 16'%3E%3Cpath d='M8 11L3 6h10z'/%3E%3C/svg%3E"); background-repeat:no-repeat; background-position:right 12px center; padding-right:34px; cursor:pointer; }
.form-row { display:grid; grid-template-columns:1fr 1fr; gap:11px; }

.calc-result-box { background:linear-gradient(135deg,var(--accent-dim),rgba(224,78,106,0.08)); border:1px solid rgba(240,165,0,0.2); border-radius:12px; padding:18px; margin-top:16px; text-align:center; }
.calc-result-box .label { font-size:0.75rem; color:var(--fg-muted); text-transform:uppercase; letter-spacing:0.8px; margin-bottom:5px; }
.calc-result-box .value { font-family:'JetBrains Mono',monospace; font-size:1.7rem; font-weight:700; color:var(--accent); word-break:break-all; }
.calc-result-box .sub { font-size:0.82rem; color:var(--fg-muted); margin-top:5px; }

.action-btn {
  width:100%; padding:13px; background:linear-gradient(135deg,var(--accent),#d4900a); color:#000;
  border:none; border-radius:var(--radius-sm); font-family:inherit; font-size:0.92rem;
  font-weight:700; cursor:pointer; transition:all 0.2s; margin-top:6px;
}
.action-btn:hover { filter:brightness(1.1); transform:translateY(-1px); box-shadow:0 6px 20px var(--accent-glow); }
.action-btn:active { transform:scale(0.98); }

/* Article / Guide Pages */
.article-page { max-width:780px; margin:0 auto; }
.article-page h1 { font-size:2rem; font-weight:700; letter-spacing:-0.5px; margin-bottom:8px; }
.article-page .meta { color:var(--fg-muted); font-size:0.82rem; margin-bottom:28px; display:flex; gap:16px; flex-wrap:wrap; }
.article-page h2 { font-size:1.25rem; font-weight:600; margin:30px 0 12px; color:var(--accent); }
.article-page h3 { font-size:1.05rem; font-weight:600; margin:22px 0 8px; }
.article-page p { color:var(--fg-muted); font-size:0.93rem; margin-bottom:14px; line-height:1.8; }
.article-page ul, .article-page ol { color:var(--fg-muted); font-size:0.93rem; margin-bottom:14px; padding-left:22px; line-height:1.8; }
.article-page li { margin-bottom:6px; }
.article-page strong { color:var(--fg); }
.article-page code { background:var(--bg2); padding:2px 7px; border-radius:4px; font-family:'JetBrains Mono',monospace; font-size:0.85rem; color:var(--accent); }
.article-page pre { background:var(--bg2); border:1px solid var(--border); border-radius:var(--radius-sm); padding:16px; overflow-x:auto; margin-bottom:18px; }
.article-page pre code { background:none; padding:0; }
.article-page blockquote { border-left:3px solid var(--accent); padding:12px 18px; margin:18px 0; background:var(--accent-dim); border-radius:0 var(--radius-sm) var(--radius-sm) 0; }
.article-page blockquote p { margin-bottom:0; }
.article-page table { width:100%; border-collapse:collapse; margin-bottom:18px; }
.article-page th, .article-page td { padding:10px 14px; border:1px solid var(--border); text-align:left; font-size:0.88rem; }
.article-page th { background:var(--bg2); color:var(--fg); font-weight:600; }
.article-page td { color:var(--fg-muted); }

/* CTA Box */
.cta-box { background:var(--card); border:1px solid var(--border); border-radius:var(--radius); padding:24px; margin:30px 0; text-align:center; }
.cta-box h3 { margin-bottom:8px; }
.cta-box a { display:inline-block; margin-top:10px; padding:10px 24px; background:linear-gradient(135deg,var(--accent),#d4900a); color:#000; border-radius:var(--radius-sm); text-decoration:none; font-weight:700; font-size:0.9rem; transition:all 0.2s; }
.cta-box a:hover { filter:brightness(1.1); transform:translateY(-1px); }

/* Related Articles */
.related-grid { display:grid; grid-template-columns:repeat(auto-fill,minmax(220px,1fr)); gap:14px; margin:24px 0; }
.related-card { background:var(--card); border:1px solid var(--border); border-radius:var(--radius-sm); padding:16px; text-decoration:none; color:var(--fg); transition:all 0.25s; }
.related-card:hover { border-color:rgba(240,165,0,0.4); transform:translateY(-2px); }
.related-card h4 { font-size:0.88rem; font-weight:600; margin-bottom:4px; }
.related-card p { font-size:0.78rem; color:var(--fg-muted); line-height:1.4; }

/* Breadcrumb */
.breadcrumb { font-size:0.8rem; color:var(--fg-muted); margin-bottom:20px; }
.breadcrumb a { color:var(--accent); text-decoration:none; }
.breadcrumb a:hover { text-decoration:underline; }

/* Footer */
footer { border-top:1px solid var(--border); padding:24px; background:rgba(12,15,20,0.6); backdrop-filter:blur(10px); }
.footer-inner { max-width:1100px; margin:0 auto; display:grid; grid-template-columns:repeat(auto-fit,minmax(180px,1fr)); gap:24px; margin-bottom:20px; }
.footer-col h4 { font-size:0.82rem; font-weight:600; text-transform:uppercase; letter-spacing:0.5px; margin-bottom:12px; color:var(--fg); }
.footer-col a { display:block; color:var(--fg-muted); text-decoration:none; font-size:0.84rem; margin-bottom:6px; transition:color 0.2s; }
.footer-col a:hover { color:var(--accent); }
.footer-bottom { border-top:1px solid var(--border); padding-top:16px; text-align:center; color:var(--fg-muted); font-size:0.78rem; }
.footer-bottom a { color:var(--accent); text-decoration:none; }

/* Toast */
.toast-container { position:fixed; bottom:24px; right:24px; z-index:9999; display:flex; flex-direction:column; gap:8px; }
.toast { background:var(--card); border:1px solid var(--border); border-radius:var(--radius-sm); padding:11px 16px; font-size:0.85rem; color:var(--fg); box-shadow:0 8px 30px rgba(0,0,0,0.4); animation:toastIn 0.35s ease; display:flex; align-items:center; gap:8px; }
.toast.success { border-left:3px solid var(--success); }
.toast.error { border-left:3px solid var(--danger); }
@keyframes toastIn { from { opacity:0; transform:translateX(40px); } to { opacity:1; transform:translateX(0); } }

/* History */
.history-list { max-height:180px; overflow-y:auto; margin-top:10px; }
.history-item { display:flex; justify-content:space-between; align-items:center; padding:7px 10px; border-radius:var(--radius-sm); font-family:'JetBrains Mono',monospace; font-size:0.8rem; color:var(--fg-muted); cursor:pointer; transition:background 0.15s; }
.history-item:hover { background:var(--accent-dim); color:var(--fg); }
.history-item .h-res { color:var(--accent); font-weight:600; margin-left:10px; }

/* Scrollbar */
::-webkit-scrollbar { width:6px; }
::-webkit-scrollbar-track { background:transparent; }
::-webkit-scrollbar-thumb { background:var(--border); border-radius:3px; }

/* Responsive */
@media (max-width:768px) {
  header { padding:10px 14px; flex-wrap:wrap; gap:8px; }
  nav { width:100%; overflow-x:auto; padding-bottom:2px; }
  main { padding:18px 14px 40px; }
  .calc-grid { grid-template-columns:1fr; }
  .calc-panel { max-width:100%; }
  .form-row { grid-template-columns:1fr; }
  .btn-grid.grid-6 { grid-template-columns:repeat(4,1fr); }
  .footer-inner { grid-template-columns:1fr 1fr; }
}
@media (max-width:400px) {
  .footer-inner { grid-template-columns:1fr; }
}
@media (prefers-reduced-motion:reduce) {
  *,*::before,*::after { animation-duration:0.01ms!important; transition-duration:0.01ms!important; }
}