/* ══════════════════════════════════════════════
   FinCalc AI — Design System v2
   ══════════════════════════════════════════════ */

/* ── Design Tokens ── */
:root {
  --bg: #0a0f1e;
  --surface: #111827;
  --surface-elevated: #1a2332;
  --glass-bg: rgba(30, 41, 59, .55);
  --glass-border: rgba(255, 255, 255, .06);

  --accent: #10b981;
  --accent-hover: #059669;
  --accent-subtle: rgba(16, 185, 129, .08);

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --border: rgba(255, 255, 255, .08);
  --border-subtle: rgba(255, 255, 255, .05);

  --radius-sm: 8px;
  --radius: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;

  --shadow-card: 0 4px 20px rgba(0, 0, 0, .2);
  --shadow-hover: 0 8px 30px rgba(0, 0, 0, .35);

  --ease-smooth: cubic-bezier(.4, 0, .2, 1);
}

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

/* ── Skip Link ── */
.skip-link { position: absolute; top: -100px; left: 16px; background: var(--accent); color: #fff; padding: 10px 20px; border-radius: 0 0 8px 8px; z-index: 1000; font-size: 14px; font-weight: 500; text-decoration: none; transition: top .2s; }
.skip-link:focus { top: 0; }

/* ── Back to Top ── */
.back-to-top { position: fixed; bottom: 24px; right: 24px; z-index: 99; width: 44px; height: 44px; border-radius: 50%; background: var(--accent); color: #fff; border: none; font-size: 20px; cursor: pointer; opacity: 0; transform: translateY(12px); pointer-events: none; transition: opacity .25s, transform .25s; box-shadow: 0 2px 12px rgba(16,185,129,0.3); }
.back-to-top.visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
.back-to-top:hover { background: var(--accent-hover); transform: translateY(-2px); }

/* ── Base ── */
html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Layout ── */
.container { max-width: 960px; margin: 0 auto; padding: 40px 20px; }

/* ── Header ── */
header { text-align: center; margin-bottom: 40px; }

h1 {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #10b981 0%, #34d399 50%, #a7f3d0 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  display: inline-block;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1.05rem;
  margin-top: 8px;
  font-weight: 400;
}

/* ── Navigation ── */
.tool-nav {
  display: flex;
  gap: 6px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 40px;
  padding: 6px;
  background: var(--surface);
  border-radius: 100px;
  border: 1px solid var(--border);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.tool-nav a {
  color: var(--text-secondary);
  text-decoration: none;
  padding: 8px 18px;
  border-radius: 100px;
  font-size: .88rem;
  font-weight: 500;
  transition: all .25s var(--ease-smooth);
  position: relative;
}

.tool-nav a:hover {
  color: var(--text-primary);
  background: var(--glass-bg);
}

.tool-nav a.active {
  background: var(--accent);
  color: #fff;
  font-weight: 600;
}

/* ── Calculator Sections ── */
.calc-section {
  background: var(--glass-bg);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 24px;
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: border-color .3s var(--ease-smooth), box-shadow .3s var(--ease-smooth);
}

.calc-section:hover {
  border-color: rgba(16, 185, 129, .2);
  box-shadow: var(--shadow-card), 0 0 0 1px rgba(16, 185, 129, .06) inset;
}

.calc-section h2 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-subtle);
  letter-spacing: -0.01em;
}

/* ── Calculator Grid ── */
.calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }

.calc-inputs label {
  display: block;
  margin-bottom: 12px;
  font-size: .88rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.calc-inputs input,
.calc-inputs select {
  width: 100%;
  padding: 10px 14px;
  margin-top: 4px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, .1);
  background: var(--surface);
  color: var(--text-primary);
  font-size: .95rem;
  transition: border-color .2s, box-shadow .2s;
  outline: none;
}

.calc-inputs input:focus,
.calc-inputs select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(16, 185, 129, .12);
}

/* ── Button ── */
.btn-calc {
  margin-top: 8px;
  padding: 11px 30px;
  font-size: .95rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-weight: 600;
  transition: all .25s var(--ease-smooth);
  letter-spacing: -0.01em;
}

.btn-calc:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 16px rgba(16, 185, 129, .3);
  transform: translateY(-1px);
}

.btn-calc:active { transform: translateY(0); }

/* ── Results ── */
.calc-results {
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: var(--surface);
  border-radius: var(--radius);
  padding: 24px;
  gap: 14px;
  border: 1px solid rgba(255, 255, 255, .04);
}

.result-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(255, 255, 255, .05);
  color: var(--text-secondary);
  font-size: .88rem;
}

.result-row:last-child { border-bottom: none; padding-bottom: 0; }

.result-row strong {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

/* ── Footer ── */
footer {
  text-align: center;
  color: var(--text-muted);
  font-size: .85rem;
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid var(--border-subtle);
}

.site-footer {
  text-align: center;
  padding: 20px 0;
  font-size: 13px;
  color: #888;
  border-top: 1px solid var(--border-subtle);
  margin-top: 40px;
}

/* ── Links ── */
a { color: var(--accent); text-decoration: none; transition: color .2s; }
a:hover { color: #34d399; }

/* ── Article body styles ── */
section p {
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 12px;
}

section h2 {
  font-size: 1.3rem;
  color: var(--text-primary);
  margin: 24px 0 8px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

/* ── Validation ── */
.calc-inputs input.invalid{border-color:#ef4444;box-shadow:0 0 0 3px rgba(239,68,68,.12)}
.calc-inputs .error-msg{color:#ef4444;font-size:.75rem;margin-top:2px;display:none}
.calc-inputs .error-msg.show{display:block}

/* ── Pulse Animation ── */
.result-row.pulse strong{animation:valuePulse .4s ease}
@keyframes valuePulse{0%,100%{transform:scale(1)}50%{transform:scale(1.08)}}

/* ── Amortization Table ── */
.amort-table{width:100%;margin-top:12px;border-collapse:collapse;font-size:.8rem;display:none}
.amort-table.show{display:table}
.amort-table th{background:var(--accent-subtle);color:var(--accent);padding:8px 10px;text-align:right;font-weight:600;border-bottom:2px solid var(--accent)}
.amort-table th:first-child{text-align:left}
.amort-table td{padding:6px 10px;text-align:right;border-bottom:1px solid var(--border-subtle);color:var(--text-secondary)}
.amort-table td:first-child{text-align:left}
.amort-table-wrap{max-height:260px;overflow-y:auto;border-radius:var(--radius-sm);border:1px solid var(--border);margin-top:12px}
.amort-table-wrap::-webkit-scrollbar{width:4px}
.amort-toggle{font-size:.8rem;color:var(--accent);background:none;border:none;cursor:pointer;margin-top:8px;font-weight:500;padding:4px 0}
.amort-toggle:hover{text-decoration:underline}

/* ── Footer Links ── */
.footer-links{display:flex;gap:20px;justify-content:center;flex-wrap:wrap;margin-bottom:12px}
.footer-links a{color:var(--text-secondary);font-size:.88rem;font-weight:500}
.footer-links a:hover{color:var(--accent)}
.footer-copy{color:var(--text-muted);font-size:.8rem;margin-top:4px}

/* ── Responsive ── */
@media (max-width: 640px) {
  .calc-grid { grid-template-columns: 1fr; }
  .container { padding: 24px 16px; }
  h1 { font-size: 1.8rem; }
  .tool-nav {
    border-radius: var(--radius);
    padding: 4px;
    gap: 2px;
  }
  .tool-nav a { padding: 7px 14px; font-size: .82rem; }
}

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* ── Featured Hero ── */
.featured-hero {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 32px;
}

.featured-card {
  background: var(--surface-elevated);
  border-radius: var(--radius-lg);
  padding: 28px;
  border: 1px solid var(--border);
  position: relative;
  transition: border-color .3s, box-shadow .3s;
}

.featured-card:hover {
  border-color: rgba(16, 185, 129, .25);
  box-shadow: var(--shadow-hover);
}

.featured-card h2 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}

.featured-card p {
  font-size: .85rem;
  color: var(--text-secondary);
  margin: 0 0 16px;
  line-height: 1.45;
}

.featured-badge {
  display: inline-block;
  font-size: .72rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-subtle);
  padding: 3px 10px;
  border-radius: 100px;
  margin-bottom: 10px;
  letter-spacing: 0.01em;
}

.featured-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 14px;
}

.featured-field label {
  display: block;
  font-size: .75rem;
  color: var(--text-muted);
  margin-bottom: 3px;
  font-weight: 500;
}

.featured-field input {
  width: 100%;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255,255,255,.1);
  background: var(--surface);
  color: var(--text-primary);
  font-size: .9rem;
  outline: none;
  transition: border-color .2s;
}

.featured-field input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(16,185,129,.12);
}

.btn-hero-calc {
  padding: 10px 24px;
  font-size: .9rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-weight: 600;
  transition: all .25s;
}

.btn-hero-calc:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 16px rgba(16,185,129,.3);
}

.hero-result {
  margin-top: 12px;
  font-size: .95rem;
  color: var(--accent);
  font-weight: 600;
}

.hero-link {
  display: inline-block;
  margin-top: 8px;
  font-size: .82rem;
  color: var(--text-muted);
}

.hero-link:hover { color: var(--accent); }

/* ── Guides Section ── */
.guides-section {
  margin-top: 16px;
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
}

.guides-section h2 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
}

.guides-subtitle {
  color: var(--text-muted);
  font-size: .9rem;
  margin: 4px 0 20px;
}

.guides-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 12px;
}

.guide-card {
  display: block;
  background: var(--glass-bg);
  border-radius: var(--radius);
  padding: 18px;
  border: 1px solid var(--glass-border);
  text-decoration: none;
  transition: all .25s;
}

.guide-card:hover {
  border-color: rgba(16,185,129,.2);
  box-shadow: var(--shadow-card);
}

.guide-icon { font-size: 1.5rem; display: block; margin-bottom: 8px; }

.guide-title {
  display: block;
  font-size: .88rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
  line-height: 1.3;
}

.guide-desc {
  display: block;
  font-size: .78rem;
  color: var(--text-muted);
  line-height: 1.4;
}

.guides-more {
  text-align: center;
  margin-top: 20px;
  font-size: .88rem;
}

/* ── Responsive Hero & Guides ── */
@media (max-width: 768px) {
  .featured-hero { grid-template-columns: 1fr; }
  .guides-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 480px) {
  .guides-grid { grid-template-columns: 1fr; }
  .featured-inputs { grid-template-columns: 1fr; }
}