/* =========================================================================
 * MFC Flow Calculator - styles
 * Mobile-first responsive, PWA friendly.
 * ========================================================================= */

:root {
  --bg: #f1f5f4;
  --card: #ffffff;
  --primary: #0f766e;
  --primary-dark: #115e59;
  --primary-light: #d1fae5;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #e5e7eb;
  --danger: #b91c1c;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

.app-header {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
  padding: 28px 20px 24px;
  text-align: center;
}
.app-header h1 { margin: 0 0 4px; font-size: 1.5rem; font-weight: 700; }
.app-header .subtitle { margin: 0; opacity: 0.85; font-size: 0.92rem; }
.install-btn {
  margin-top: 14px;
  background: #fff;
  color: var(--primary-dark);
  font-weight: 600;
  border: none;
  border-radius: 999px;
  padding: 8px 20px;
  cursor: pointer;
}
.install-btn.hidden { display: none; }

.container {
  max-width: 820px;
  margin: 0 auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px 20px;
}
.card h2 { margin: 0 0 14px; font-size: 1.05rem; color: var(--primary-dark); }
.card h3 { margin: 18px 0 8px; font-size: 0.92rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.03em; }

.field { margin-bottom: 14px; }
.field label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 6px;
}
.field input[type="number"],
.field select {
  width: 100%;
  padding: 10px 12px;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
}
.field input[type="number"]:focus,
.field select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.15);
}

.flow-row { display: flex; gap: 8px; }
.flow-row input { flex: 1; }
.flow-row select { width: auto; }

.link-btn {
  background: none;
  border: none;
  color: var(--primary);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  padding: 4px 0;
  text-decoration: underline;
  text-underline-offset: 2px;
}
.link-btn:hover { color: var(--primary-dark); }

/* segmented control */
.segmented { display: flex; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.segmented button {
  flex: 1;
  padding: 10px 8px;
  background: #fff;
  border: none;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
}
.segmented button.active { background: var(--primary); color: #fff; }

/* range slider */
.range-wrap { margin-top: 10px; }
.range-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 6px;
}
input[type="range"] { width: 100%; accent-color: var(--primary); }

.hidden { display: none !important; }

/* results */
.hero-result {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--primary-light);
  border-radius: var(--radius);
  padding: 22px 16px;
  margin-bottom: 16px;
}
.hero-value {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--primary-dark);
  font-variant-numeric: tabular-nums;
}
.hero-label { font-size: 0.85rem; color: var(--primary-dark); opacity: 0.8; text-transform: uppercase; letter-spacing: 0.05em; }

.key-values {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 10px;
  margin-bottom: 8px;
}
.kv {
  background: #f8faf9;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
}
.kv-label { display: block; font-size: 0.72rem; color: var(--muted); margin-bottom: 4px; }
.kv-value { font-size: 1.05rem; font-weight: 700; font-variant-numeric: tabular-nums; }

.out-table { width: 100%; border-collapse: collapse; font-size: 0.95rem; }
.out-table th, .out-table td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }
.out-table th { color: var(--muted); font-size: 0.8rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.03em; }
.out-table td.value { text-align: right; font-variant-numeric: tabular-nums; font-weight: 600; }
.out-table tr:last-child td { border-bottom: none; }

.ref-note { margin-top: 12px; font-size: 0.8rem; color: var(--muted); }

.ref-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }

.temp-readout {
  margin-top: 4px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary-dark);
  background: var(--primary-light);
  border-radius: 8px;
  padding: 8px 12px;
  font-variant-numeric: tabular-nums;
}

/* modal */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 24px 12px;
  z-index: 50;
  overflow-y: auto;
}
.modal {
  background: #fff;
  border-radius: var(--radius);
  padding: 20px;
  width: 100%;
  max-width: 520px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.25);
}
.modal-wide { max-width: 680px; }
.modal h2 { margin: 0 0 10px; font-size: 1.1rem; color: var(--primary-dark); }
.modal-actions { margin-top: 16px; display: flex; justify-content: flex-end; gap: 8px; }

.btn {
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 9px 16px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
}
.btn:hover { background: var(--primary-dark); }
.btn.secondary { background: #e5e7eb; color: var(--text); }
.btn.secondary:hover { background: #d1d5db; }
.btn.danger { background: transparent; color: var(--danger); border: 1px solid var(--danger); }

.hint { font-size: 0.82rem; color: var(--muted); margin-top: 0; }

/* editor rows */
.editor-item {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  margin-bottom: 10px;
  background: #fafbfa;
}
.editor-item .row { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; margin-bottom: 8px; }
.editor-item .row label { font-size: 0.75rem; color: var(--muted); display: block; margin-bottom: 2px; }
.editor-item input[type="text"], .editor-item input[type="number"], .editor-item select {
  padding: 6px 8px;
  font-size: 0.88rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: #fff;
}
.editor-item .grow { flex: 1; min-width: 120px; }
.components-list { display: flex; flex-direction: column; gap: 6px; margin: 8px 0; }
.component-row { display: flex; gap: 6px; align-items: center; }
.component-row select { flex: 1; }
.component-row input { width: 88px; }
.frac-hint { font-size: 0.72rem; color: var(--muted); }

footer.app-footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.75rem;
  padding: 18px 12px 30px;
}

/* small screens */
@media (max-width: 480px) {
  .key-values { grid-template-columns: 1fr 1fr; }
  .ref-grid { grid-template-columns: 1fr; }
}