/* ============================================================
   Electricity Bill Calculator — FA Shopnil
   Theme: Midnight Spark (matches root site)
   Fonts: Poppins
   ============================================================ */

:root {
  --bg: #020617;
  --surface: #0b1220;
  --surface-2: #101a2e;
  --border: #1e293b;
  --border-focus: #38bdf8;
  --text: #f1f5f9;
  --text-dim: #94a3b8;
  --accent: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.12);
  --font: "Poppins", system-ui, sans-serif;
  --radius: 14px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--accent);
  color: var(--bg);
  padding: 0.5rem 1rem;
  z-index: 10;
}
.skip-link:focus { left: 1rem; }

/* ---------- Navbar ---------- */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem clamp(1rem, 5vw, 3rem);
  background: rgba(2, 6, 23, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 5;
}

.navbar .logo img { height: 42px; width: auto; display: block; }

.nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s ease;
}
.nav-links a:hover { color: var(--accent); }

/* ---------- Layout ---------- */
main {
  flex: 1;
  width: min(1080px, 100% - 2rem);
  margin: 0 auto;
  padding: 2.5rem 0 4rem;
}

.page-header { text-align: center; margin-bottom: 2.5rem; }

.badge {
  display: inline-block;
  padding: 0.35rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

.page-header h1 {
  font-size: clamp(1.7rem, 4vw, 2.6rem);
  font-weight: 800;
  line-height: 1.2;
}
.page-header h1 span { color: var(--accent); }

.page-header p {
  color: var(--text-dim);
  max-width: 620px;
  margin: 0.8rem auto 0;
  font-size: 0.95rem;
}

/* ---------- Calculator ---------- */
.calculator {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  align-items: start;
}

.calc-form,
.result {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: clamp(1.2rem, 3vw, 2rem);
}

.field { margin-bottom: 1.3rem; }

.field label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.45rem;
}

.field select,
.field input[type="number"] {
  width: 100%;
  padding: 0.75rem 0.9rem;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  font-family: var(--font);
  font-size: 1rem;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.field select:focus,
.field input[type="number"]:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

#units { font-size: 1.25rem; font-weight: 600; }

.hint {
  font-size: 0.76rem;
  color: var(--text-dim);
  margin-top: 0.4rem;
}

.quick-units {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.7rem;
}

.chip {
  padding: 0.3rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--text-dim);
  font-family: var(--font);
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}
.chip:hover { border-color: var(--accent); color: var(--accent); }

.advanced {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.8rem 1rem;
  margin-top: 0.5rem;
}

.advanced summary {
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--accent);
  user-select: none;
}

.advanced .field { margin-top: 1rem; margin-bottom: 0.8rem; }

.field-check {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.field-check label { margin: 0; }
.field-check input {
  width: 18px; height: 18px;
  accent-color: var(--accent);
  cursor: pointer;
}

/* ---------- Result ---------- */
.result { position: sticky; top: 90px; }

.result-empty {
  color: var(--text-dim);
  text-align: center;
  padding: 2.5rem 0;
  font-size: 0.92rem;
}

.result-utility {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.total-label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-dim);
  margin-top: 0.6rem;
}

.total {
  font-size: clamp(2rem, 5vw, 2.8rem);
  font-weight: 800;
  color: var(--accent);
  line-height: 1.1;
  margin-bottom: 0.2rem;
}

.avg {
  font-size: 0.82rem;
  color: var(--text-dim);
  margin-bottom: 1.2rem;
}

.breakdown {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.breakdown th {
  text-align: left;
  color: var(--text-dim);
  font-weight: 600;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.5rem 0.4rem;
  border-bottom: 1px solid var(--border);
}

.breakdown td {
  padding: 0.45rem 0.4rem;
  border-bottom: 1px solid var(--border);
  color: var(--text);
}

.breakdown .amount { text-align: right; white-space: nowrap; }

.subtotal-row td {
  font-weight: 700;
  background: var(--surface-2);
}

.copy-btn {
  margin-top: 1.2rem;
  width: 100%;
  padding: 0.7rem;
  background: var(--accent-soft);
  border: 1px solid var(--accent);
  border-radius: 10px;
  color: var(--accent);
  font-family: var(--font);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.copy-btn:hover { background: var(--accent); color: var(--bg); }

/* ---------- Info sections ---------- */
.info {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-top: 2.5rem;
}

.info-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: clamp(1.2rem, 3vw, 1.8rem);
}

.info-card h2 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.info-sub {
  font-size: 0.82rem;
  color: var(--text-dim);
  margin-bottom: 1rem;
}

.slab-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.slab-table th {
  text-align: left;
  color: var(--text-dim);
  font-weight: 600;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.5rem 0.4rem;
  border-bottom: 1px solid var(--border);
}

.slab-table td {
  padding: 0.45rem 0.4rem;
  border-bottom: 1px solid var(--border);
}
.slab-table td:last-child { text-align: right; font-weight: 600; color: var(--accent); }

.info-list {
  list-style: none;
  display: grid;
  gap: 0.6rem;
  font-size: 0.88rem;
}

.info-list li { padding-left: 1.2rem; position: relative; }
.info-list li::before {
  content: "";
  position: absolute;
  left: 0; top: 0.55em;
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--accent);
}

.info-note {
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-top: 1rem;
  padding-top: 0.8rem;
  border-top: 1px dashed var(--border);
}

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid var(--border);
  padding: 1.4rem;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-dim);
}
.footer a { color: var(--accent); text-decoration: none; }
.footer a:hover { text-decoration: underline; }

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  .calculator { grid-template-columns: 1fr; }
  .result { position: static; }
  .info { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .navbar { flex-direction: column; }
  .nav-links { flex-wrap: wrap; justify-content: center; gap: 0.9rem; }
}