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

:root {
  --bg: #0a0b0d;
  --surface: #111318;
  --surface2: #181c24;
  --border: #252b38;
  --border2: #2e3748;
  --text: #e8eaf0;
  --text2: #8a95a8;
  --text3: #4a5568;
  --accent: #f0b429;
  --accent2: #f6d860;
  --green: #3ecf8e;
  --green2: #6ee7b7;
  --petrol: #f0b429;
  --ethanol: #3ecf8e;
  --radius: 16px;
  --radius-sm: 10px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Syne', sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 2rem 1rem 4rem;
  position: relative;
  overflow-x: hidden;
}

.bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: 0.3;
  pointer-events: none;
  z-index: 0;
}

.bg-glow {
  position: fixed;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 500px;
  background: radial-gradient(ellipse, rgba(240,180,41,0.07) 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

main {
  width: 100%;
  max-width: 560px;
  position: relative;
  z-index: 1;
}

/* ── HEADER ── */
header {
  text-align: center;
  margin-bottom: 2.5rem;
  animation: fadeDown 0.6s ease both;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.4rem;
}

.logo-icon {
  font-size: 2rem;
  line-height: 1;
}

.logo-text {
  font-size: 2.6rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  color: var(--text);
}

.logo-text em {
  font-style: normal;
  color: var(--accent);
}

.subtitle {
  color: var(--text2);
  font-size: 0.9rem;
  font-weight: 400;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* ── CARDS ── */
.card, .result-card, .info-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 1.25rem;
}

.card {
  animation: fadeUp 0.5s 0.1s ease both;
}

/* ── FIELDS ── */
.field-group {
  margin-bottom: 1.4rem;
}

label {
  display: block;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text2);
  margin-bottom: 0.55rem;
}

label .unit {
  font-weight: 400;
  color: var(--text3);
  text-transform: none;
  letter-spacing: 0;
}

.input-wrap {
  position: relative;
}

input[type="number"] {
  width: 100%;
  background: var(--surface2);
  border: 1.5px solid var(--border2);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: 'DM Mono', monospace;
  font-size: 1.2rem;
  font-weight: 500;
  padding: 0.85rem 3rem 0.85rem 1.1rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s, background 0.2s;
  -moz-appearance: textfield;
}

input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
}

input[type="number"]::placeholder {
  color: var(--text3);
  font-size: 1rem;
}

input[type="number"]:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(240,180,41,0.12);
  background: #1a1e28;
}

.input-icon {
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.2rem;
  pointer-events: none;
}

/* ── PRESETS ── */
.preset-row {
  display: flex;
  gap: 0.4rem;
  margin-top: 0.55rem;
  flex-wrap: wrap;
}

.preset {
  background: transparent;
  border: 1px solid var(--border2);
  border-radius: 6px;
  color: var(--text2);
  font-family: 'DM Mono', monospace;
  font-size: 0.72rem;
  font-weight: 500;
  padding: 0.3rem 0.65rem;
  cursor: pointer;
  transition: all 0.15s;
  letter-spacing: 0.03em;
}

.preset:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(240,180,41,0.06);
}

.preset.active {
  border-color: var(--accent);
  color: var(--accent);
  background: rgba(240,180,41,0.1);
}

/* ── DIVIDER ── */
.divider {
  position: relative;
  text-align: center;
  margin: 1.8rem 0;
}

.divider::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: 1px;
  background: var(--border2);
}

.divider span {
  position: relative;
  background: var(--surface);
  padding: 0 0.8rem;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text3);
}

/* ── BUTTON ── */
.btn-calc {
  width: 100%;
  background: var(--accent);
  border: none;
  border-radius: var(--radius-sm);
  color: #0a0b0d;
  font-family: 'Syne', sans-serif;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 1rem;
  cursor: pointer;
  margin-top: 0.5rem;
  transition: background 0.2s, transform 0.1s, box-shadow 0.2s;
  box-shadow: 0 4px 20px rgba(240,180,41,0.2);
}

.btn-calc:hover {
  background: var(--accent2);
  box-shadow: 0 6px 30px rgba(240,180,41,0.35);
}

.btn-calc:active {
  transform: scale(0.98);
}

/* ── RESULT ── */
.result-card {
  animation: fadeUp 0.4s ease both;
}

.result-card.hidden {
  display: none;
}

.result-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.6rem;
}

.result-title {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text2);
}

.result-tag {
  background: rgba(62,207,142,0.15);
  border: 1px solid rgba(62,207,142,0.4);
  border-radius: 6px;
  color: var(--green);
  font-family: 'DM Mono', monospace;
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.25rem 0.7rem;
}

/* ── BARS ── */
.result-bars {
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
  margin-bottom: 1.6rem;
}

.bar-item {}

.bar-label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.45rem;
  font-size: 0.85rem;
  color: var(--text2);
}

.bar-value {
  font-family: 'DM Mono', monospace;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text);
}

.bar-track {
  background: var(--surface2);
  border-radius: 99px;
  height: 10px;
  overflow: hidden;
  border: 1px solid var(--border);
}

.bar-fill {
  height: 100%;
  border-radius: 99px;
  transition: width 0.7s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  width: 0%;
}

.bar-fill.petrol {
  background: linear-gradient(90deg, var(--petrol), var(--accent2));
}

.bar-fill.ethanol {
  background: linear-gradient(90deg, var(--ethanol), var(--green2));
}

/* ── STATS ── */
.result-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  margin-bottom: 1.2rem;
}

.stat {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.85rem 0.75rem;
  text-align: center;
}

.stat-label {
  display: block;
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text3);
  margin-bottom: 0.4rem;
}

.stat-value {
  display: block;
  font-family: 'DM Mono', monospace;
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--text);
}

/* ── NOTE ── */
.result-note {
  font-size: 0.82rem;
  color: var(--text2);
  line-height: 1.6;
  padding: 0.9rem 1rem;
  background: var(--surface2);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--accent);
}

.result-note.warning {
  border-left-color: #e53e3e;
  color: #fc8181;
}

.result-note.success {
  border-left-color: var(--green);
}

.result-note:empty {
  display: none;
}

/* ── INFO CARD ── */
.info-card {
  animation: fadeUp 0.5s 0.2s ease both;
}

.info-card h2 {
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text2);
  margin-bottom: 0.75rem;
}

.info-card p {
  font-size: 0.88rem;
  color: var(--text2);
  line-height: 1.7;
  margin-bottom: 1rem;
}

.formula {
  background: var(--surface2);
  border: 1px solid var(--border2);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  overflow-x: auto;
}

.dm {
  font-family: 'DM Mono', monospace;
  font-size: 0.78rem;
  color: var(--accent);
  white-space: nowrap;
}

/* ── FOOTER ── */
footer {
  position: relative;
  z-index: 1;
  text-align: center;
  margin-top: 1rem;
  color: var(--text3);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
}

/* ── ANIMATIONS ── */
@keyframes fadeDown {
  from { opacity: 0; transform: translateY(-16px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── RESPONSIVE ── */
@media (max-width: 480px) {
  .card, .result-card, .info-card {
    padding: 1.4rem;
  }

  .result-stats {
    grid-template-columns: 1fr 1fr;
  }

  .result-stats .stat:last-child {
    grid-column: span 2;
  }

  .logo-text {
    font-size: 2rem;
  }
}

/* ══════════════════════════════════════
   MOBILE & PWA IMPROVEMENTS
   ══════════════════════════════════════ */

/* Safe area for notched phones */
body {
  padding-bottom: max(4rem, env(safe-area-inset-bottom));
  padding-left: max(1rem, env(safe-area-inset-left));
  padding-right: max(1rem, env(safe-area-inset-right));
  padding-top: max(2rem, env(safe-area-inset-top));
}

/* Install Banner */
.install-banner {
  position: fixed;
  bottom: max(1.2rem, env(safe-area-inset-bottom));
  left: 50%;
  transform: translateX(-50%);
  z-index: 100;
  background: var(--surface2);
  border: 1px solid var(--accent);
  border-radius: 14px;
  padding: 0.85rem 1.1rem;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  box-shadow: 0 8px 32px rgba(240,180,41,0.2);
  width: calc(100% - 2.4rem);
  max-width: 480px;
  animation: slideUp 0.4s ease;
}

.install-banner.hidden {
  display: none;
}

.install-icon {
  font-size: 1.25rem;
  flex-shrink: 0;
}

.install-text {
  font-size: 0.82rem;
  color: var(--text2);
  flex: 1;
  line-height: 1.4;
}

.install-btn {
  background: var(--accent);
  border: none;
  border-radius: 8px;
  color: #0a0b0d;
  font-family: 'Syne', sans-serif;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  padding: 0.45rem 0.9rem;
  cursor: pointer;
  white-space: nowrap;
  flex-shrink: 0;
  transition: background 0.15s;
}

.install-btn:hover { background: var(--accent2); }

.install-close {
  background: transparent;
  border: none;
  color: var(--text3);
  cursor: pointer;
  font-size: 0.9rem;
  padding: 0.2rem;
  flex-shrink: 0;
  transition: color 0.15s;
}

.install-close:hover { color: var(--text); }

@keyframes slideUp {
  from { opacity: 0; transform: translateX(-50%) translateY(20px); }
  to   { opacity: 1; transform: translateX(-50%) translateY(0); }
}

/* ── Touch targets: make buttons bigger on mobile ── */
@media (pointer: coarse) {
  .preset {
    padding: 0.5rem 0.85rem;
    font-size: 0.78rem;
    min-height: 40px;
  }

  .btn-calc {
    padding: 1.15rem;
    font-size: 1.05rem;
  }

  input[type="number"] {
    padding: 1rem 3rem 1rem 1.1rem;
    font-size: 1.25rem;
  }

  .install-close {
    min-width: 32px;
    min-height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
  }
}

/* ── Small phones (< 360px) ── */
@media (max-width: 360px) {
  .logo-text { font-size: 1.8rem; }
  .card, .result-card, .info-card { padding: 1.1rem; }
  .result-stats { grid-template-columns: 1fr 1fr; }
  .result-stats .stat:last-child { grid-column: span 2; }
  .preset-row { gap: 0.3rem; }
  .preset { padding: 0.4rem 0.6rem; font-size: 0.7rem; }
}

/* ── Tablet / Desktop wide ── */
@media (min-width: 768px) {
  main { max-width: 600px; }

  .result-stats {
    grid-template-columns: repeat(3, 1fr);
  }

  /* Side-by-side layout for wider screens */
  .field-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
  }
}

/* ── Standalone PWA mode tweaks ── */
@media (display-mode: standalone) {
  header {
    padding-top: 0.5rem;
  }

  footer {
    padding-bottom: max(0.5rem, env(safe-area-inset-bottom));
  }
}

/* ── Reduce motion ── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}