/* ============================================================
   Photoelectric Effect Simulator — Stylesheet
   Design tokens
   Colors: bg #0B0E11, panel #12161B, text #ECE7D8, muted #9AA1AF,
           amber #FFB300, cyan #4FD8E8, red #E8584A, green #6FCF8F
   Type:   display/body  -> 'Source Serif 4'
           technical/data -> 'IBM Plex Mono'
   ============================================================ */

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: #0B0E11;
}

.pe-app {
  background: #0B0E11;
  color: #ECE7D8;
  font-family: 'Source Serif 4', Georgia, serif;
  padding: 22px 16px 34px;
  min-height: 100vh;
  display: flex;
  justify-content: center;
}

.pe-inner {
  width: 100%;
  max-width: 620px;
}

.pe-eyebrow {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: #FFB300;
  text-transform: uppercase;
  margin-bottom: 6px;
}

.pe-title {
  font-size: 26px;
  font-weight: 600;
  margin: 0 0 6px;
  letter-spacing: -0.01em;
}

.pe-subtitle {
  color: #9AA1AF;
  font-size: 14.5px;
  line-height: 1.5;
  margin: 0 0 20px;
  max-width: 46em;
}

.pe-panel {
  background: #12161B;
  border: 1px solid #232830;
  border-radius: 10px;
  padding: 14px;
  margin-bottom: 14px;
}

/* ---------- Simulation tube ---------- */

.pe-tube-wrap {
  position: relative;
  height: 190px;
  border-radius: 8px;
  overflow: hidden;
  background: #07090B;
  border: 1px solid #1C2127;
}

#peCanvas {
  display: block;
}

.pe-tube-label {
  position: absolute;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 10px;
  letter-spacing: 0.08em;
  color: #6F7684;
  text-transform: uppercase;
  pointer-events: none;
}

/* ---------- Metal selector ---------- */

.pe-metal-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 14px 0 6px;
}

.pe-metal-btn {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 12.5px;
  background: #12161B;
  border: 1px solid #262C34;
  color: #9AA1AF;
  padding: 7px 12px;
  border-radius: 20px;
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}

.pe-metal-btn:hover {
  border-color: #3A4250;
  color: #ECE7D8;
}

.pe-metal-btn.active {
  background: rgba(255, 179, 0, 0.10);
  border-color: #FFB300;
  color: #FFB300;
}

.pe-metal-btn:focus-visible,
.pe-slider:focus-visible {
  outline: 2px solid #4FD8E8;
  outline-offset: 2px;
}

/* ---------- Sliders ---------- */

.pe-control {
  margin: 18px 0 6px;
}

.pe-control-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 11.5px;
  color: #9AA1AF;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
}

.pe-control-val {
  color: #ECE7D8;
  font-size: 12.5px;
  letter-spacing: 0;
  text-transform: none;
}

.pe-slider-wrap {
  position: relative;
  padding-top: 10px;
}

.pe-thresh-mark {
  position: absolute;
  top: 0;
  left: 0;
  width: 0;
  height: 8px;
  border-left: 1.5px dashed #E8584A;
  transform: translateX(-0.5px);
}

.pe-thresh-label {
  position: absolute;
  top: -13px;
  left: 0;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 9px;
  color: #E8584A;
  transform: translateX(-50%);
  white-space: nowrap;
}

input[type="range"].pe-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--track-bg, #1E232A);
  outline: none;
  margin: 0;
}

input[type="range"].pe-slider::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 3px;
  background: var(--track-bg, #1E232A);
}

input[type="range"].pe-slider::-moz-range-track {
  height: 6px;
  border-radius: 3px;
  background: var(--track-bg, #1E232A);
}

input[type="range"].pe-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 17px;
  height: 17px;
  border-radius: 50%;
  background: var(--thumb-color, #ECE7D8);
  border: 2px solid #0B0E11;
  box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.25), 0 0 10px var(--thumb-glow, transparent);
  margin-top: -5.5px;
  cursor: pointer;
}

input[type="range"].pe-slider::-moz-range-thumb {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  background: var(--thumb-color, #ECE7D8);
  border: 2px solid #0B0E11;
  cursor: pointer;
}

/* ---------- Stat readout ---------- */

.pe-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 4px;
}

.pe-stat {
  background: #0D1013;
  border: 1px solid #1E232A;
  border-radius: 8px;
  padding: 10px 12px;
}

.pe-stat-label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 10px;
  color: #6F7684;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 5px;
}

.pe-stat-val {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 19px;
  font-weight: 500;
  color: #ECE7D8;
}

.pe-status {
  grid-column: span 2;
  display: flex;
  align-items: center;
  gap: 9px;
  background: #0D1013;
  border: 1px solid #1E232A;
  border-radius: 8px;
  padding: 10px 12px;
}

.pe-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  flex-shrink: 0;
  background: #E8584A;
}

.pe-status-text {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 13px;
  letter-spacing: 0.06em;
  color: #E8584A;
}

/* ---------- Graph ---------- */

.pe-graph-title {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 11px;
  color: #9AA1AF;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
}

.pe-graph-svg {
  width: 100%;
  height: auto;
  display: block;
}

.pe-caption {
  font-size: 13.5px;
  line-height: 1.6;
  color: #9AA1AF;
  margin: 4px 0 0;
}

.pe-note {
  font-size: 14px;
  line-height: 1.65;
  color: #C7C2B0;
  margin: 0;
}

.pe-note b {
  color: #ECE7D8;
}

/* ---------- Accessibility / motion ---------- */

@media (prefers-reduced-motion: reduce) {
  .pe-metal-btn {
    transition: none;
  }
}

@media (max-width: 380px) {
  .pe-title { font-size: 22px; }
  .pe-stat-val { font-size: 17px; }
}