.fuel-diagram {
  --ink: #3d3d3a;
  --muted: #6b6b66;
  --line: #c9c8c2;
  --card: #ffffff;
  --page: #f4f3ee;
  --green: #4c9a2a;
  --red: #c0392b;
  --gray: #8a8a86;
  --box: #333333;
  position: relative;
  max-width: 1040px;
  margin: 0 auto;
  background: var(--card);
  border-radius: 10px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 8px 24px rgba(0, 0, 0, 0.06);
  padding: 36px 44px 30px;
  color: var(--ink);
}

.fuel-diagram * {
  box-sizing: border-box;
}

.fuel-diagram .kicker {
  text-align: center;
  font-size: 12px;
  letter-spacing: 0.04em;
  color: #7a7a4a;
  margin: 0 0 4px;
}

.fuel-diagram h1 {
  text-align: center;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 400;
  font-size: 38px;
  margin: 0 0 22px;
  color: #454541;
}

.fuel-diagram .subhead-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  border-bottom: 1px dashed #b9c8d6;
  padding-bottom: 10px;
  margin-bottom: 22px;
  flex-wrap: wrap;
}

.fuel-diagram h2 {
  font-size: 19px;
  font-weight: 700;
  margin: 0;
  color: #2c2c2a;
}

.fuel-diagram .toggle {
  display: flex;
  gap: 8px;
}

.fuel-diagram .toggle button {
  border: 1px solid #c8c7c1;
  background: #fff;
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  color: #555;
  transition: all 0.15s;
}

.fuel-diagram .toggle button.active {
  background: #333;
  color: #fff;
  border-color: #333;
}

.fuel-diagram .toggle button:hover:not(.active) {
  background: #f2f2ee;
}

.fuel-diagram svg {
  display: block;
  width: 100%;
  height: auto;
}

.fuel-diagram .box rect,
.fuel-diagram .box circle {
  fill: #fff;
  stroke: var(--box);
  stroke-width: 1.3;
  transition: stroke 0.3s, fill 0.15s, stroke-width 0.15s;
}

.fuel-diagram .box {
  cursor: pointer;
}

.fuel-diagram .box:hover rect,
.fuel-diagram .box:hover circle {
  fill: #fafaf3;
  stroke-width: 2.2;
}

.fuel-diagram .box text {
  font-family: -apple-system, Segoe UI, Helvetica, Arial, sans-serif;
  fill: #222;
  pointer-events: none;
}

.fuel-diagram .title-t {
  font-size: 15px;
  font-weight: 700;
}

.fuel-diagram .sub-t {
  font-size: 11px;
  font-weight: 600;
}

.fuel-diagram .plain-t {
  font-size: 12px;
  fill: #6b6b66;
}

.fuel-diagram .dashed-container {
  fill: none;
  stroke: #9a9a94;
  stroke-width: 1;
  stroke-dasharray: 4 3;
}

.fuel-diagram .hmu-label {
  font-size: 12px;
  fill: #6b6b66;
}

.fuel-diagram .pipe {
  stroke-width: 5;
  fill: none;
  stroke-linecap: round;
  stroke-dasharray: 14 9;
  transition: stroke 0.3s, opacity 0.3s;
}

.fuel-diagram .pipe.thin {
  stroke-width: 3;
  stroke-dasharray: 9 6;
}

.fuel-diagram .pipe.flowing {
  animation: fuel-flowmove 0.7s linear infinite;
}

@keyframes fuel-flowmove {
  to {
    stroke-dashoffset: -23;
  }
}

@media (prefers-reduced-motion: reduce) {
  .fuel-diagram .pipe.flowing {
    animation: none;
  }
}

.fuel-diagram .valve-state {
  font-size: 11px;
  font-weight: 700;
}

.fuel-diagram .caption {
  font-size: 14px;
  line-height: 1.6;
  color: #3d3d3a;
  margin-top: 26px;
  padding-top: 16px;
  border-top: 1px dashed #ccc;
}

.fuel-diagram .tooltip {
  position: absolute;
  display: none;
  max-width: 260px;
  background: #2c2c2a;
  color: #f2f2ee;
  font-size: 13px;
  line-height: 1.5;
  padding: 10px 12px;
  border-radius: 8px;
  pointer-events: none;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.25);
  z-index: 20;
}

.fuel-diagram .tooltip strong {
  display: block;
  font-size: 13px;
  margin-bottom: 3px;
  color: #fff;
}