/* Physics variant — extends base style */

body.physics-variant .grid-bg {
  background-image: none;
  background: var(--gray-50);
}

body.physics-variant .grid-bg::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400' viewBox='0 0 400 400'%3E%3Cpath d='M0 200 Q100 120 200 200 T400 200' fill='none' stroke='%23e0e0e0' stroke-width='1'/%3E%3Cpath d='M0 160 Q100 80 200 160 T400 160' fill='none' stroke='%23e8e8e8' stroke-width='1'/%3E%3Cpath d='M0 240 Q100 160 200 240 T400 240' fill='none' stroke='%23e8e8e8' stroke-width='1'/%3E%3Cpath d='M0 120 Q100 200 200 120 T400 120' fill='none' stroke='%23ececec' stroke-width='1'/%3E%3Cpath d='M0 280 Q100 360 200 280 T400 280' fill='none' stroke='%23ececec' stroke-width='1'/%3E%3C/svg%3E");
  background-size: 400px 400px;
  opacity: 0.7;
  mask-image: radial-gradient(ellipse 90% 70% at 60% 20%, black 10%, transparent 75%);
}

body.physics-variant .logo-mark {
  font-size: 0.85rem;
  letter-spacing: -0.05em;
}

/* Atom visual */
.atom-svg {
  width: min(360px, 90%);
  height: auto;
}

.atom-orbit {
  fill: none;
  stroke: var(--gray-300);
  stroke-width: 1;
  transform-origin: 200px 200px;
}

.atom-orbit-1 { animation: atom-spin 8s linear infinite; }
.atom-orbit-2 { animation: atom-spin 12s linear infinite reverse; stroke: var(--orange); stroke-opacity: 0.4; }
.atom-orbit-3 { animation: atom-spin 16s linear infinite; stroke-dasharray: 3 6; }

.atom-nucleus {
  fill: var(--orange);
  filter: drop-shadow(0 0 24px var(--orange-glow));
}

.atom-electron {
  fill: var(--black);
}

.atom-electron-orange { fill: var(--orange); }

@keyframes atom-spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* Field lines accent */
.field-lines {
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.35;
}

.field-lines path {
  fill: none;
  stroke: var(--orange);
  stroke-width: 0.8;
  stroke-dasharray: 4 8;
}

.hero-visual {
  position: relative;
}

/* Physics constants strip */
.physics-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
  justify-content: center;
}

.physics-strip code {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--gray-500);
  background: var(--white);
  border: 1px solid var(--gray-100);
  padding: 0.35rem 0.7rem;
  border-radius: 6px;
}

.physics-strip code em {
  font-style: normal;
  color: var(--orange);
  font-weight: 500;
}

/* Interference graphic for project */
.interference-chart {
  height: 80px;
  background: var(--gray-50);
  border-radius: 8px;
  border: 1px solid var(--gray-100);
  overflow: hidden;
}

.interference-chart svg { width: 100%; height: 100%; }

.interf-band {
  fill: none;
  stroke: var(--orange);
  stroke-width: 1.5;
  stroke-linecap: round;
  opacity: 0.85;
}

.interf-band-2 {
  stroke: var(--gray-300);
  stroke-width: 1;
  opacity: 0.6;
}

/* Spectrum bar in about */
.spectrum-bar {
  display: flex;
  height: 4px;
  border-radius: 2px;
  overflow: hidden;
  margin-top: 1.5rem;
  max-width: 280px;
}

.spectrum-bar span {
  flex: 1;
  background: linear-gradient(90deg,
    var(--gray-300) 0%,
    var(--orange) 50%,
    var(--black) 100%
  );
}

.spectrum-labels {
  display: flex;
  justify-content: space-between;
  max-width: 280px;
  margin-top: 0.4rem;
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--gray-500);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}