:root {
  --lab-text: #1f2933;
  --lab-muted: rgba(31, 41, 51, 0.72);
  --lab-surface: rgba(255, 255, 255, 0.76);
  --lab-surface-strong: rgba(255, 255, 255, 0.9);
  --lab-border: rgba(13, 74, 124, 0.16);
  --lab-shadow: 0 18px 40px rgba(13, 35, 61, 0.12);
  --lab-primary: #0d4a7c;
  --lab-primary-hover: #15629d;
  --lab-primary-active: #0a3b63;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  overflow: hidden;
  text-align: center;
  font: 400 15px/1.45 "Libre Franklin", sans-serif;
  color: var(--lab-text);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  background:
    radial-gradient(circle at top left, rgba(120, 180, 220, 0.2), transparent 28%),
    linear-gradient(180deg, #f5f8fb 0%, #e6eef5 100%);
}

h1 {
  position: absolute;
  top: 1.15rem;
  left: 50%;
  transform: translateX(-50%);
  width: min(92vw, 820px);
  margin: 0;
  padding: 0.9rem 1.4rem;
  z-index: 2;
  border: 1px solid var(--lab-border);
  border-radius: 1rem;
  background: var(--lab-surface);
  backdrop-filter: blur(14px);
  box-shadow: var(--lab-shadow);
  color: var(--lab-text);
  font: 400 clamp(1.15rem, 2vw, 1.9rem)/1.15 "Tenor Sans", sans-serif;
  letter-spacing: 0.025em;
}

#scene-container {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.button_st {
  position: absolute;
  z-index: 2;
  width: 214px;
  min-height: 52px;
  padding: 0.8rem 1rem;
  border: 1px solid rgba(13, 74, 124, 0.18);
  border-radius: 0.95rem;
  background: linear-gradient(180deg, var(--lab-surface-strong) 0%, rgba(233, 241, 248, 0.96) 100%);
  box-shadow: var(--lab-shadow);
  color: var(--lab-text);
  font: 500 0.95rem/1.25 "Libre Franklin", sans-serif;
  letter-spacing: 0.01em;
  text-align: left;
  text-decoration: none;
  cursor: pointer;
  transition:
    transform 0.18s ease,
    box-shadow 0.18s ease,
    border-color 0.18s ease,
    background 0.18s ease;
}

.button_st:hover {
  transform: translateY(-1px);
  border-color: rgba(13, 74, 124, 0.3);
  box-shadow: 0 20px 44px rgba(13, 35, 61, 0.16);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.98) 0%, rgba(225, 237, 247, 0.98) 100%);
}

.button_st:active {
  transform: translateY(0);
  box-shadow: 0 10px 24px rgba(13, 35, 61, 0.12);
  border-color: rgba(13, 74, 124, 0.24);
  background: linear-gradient(180deg, rgba(228, 238, 246, 0.98) 0%, rgba(214, 228, 239, 0.98) 100%);
}

#LEDs_background { top: 104px; left: 28px; }
#LEDs_obj { top: 166px; left: 28px; }
#Channel_LEDs_obj { top: 228px; left: 28px; }
#Absorbing_filter { top: 290px; left: 28px; }
#Color_filters { top: 352px; left: 28px; }
#Monochromator { top: 414px; left: 28px; }
#Shar { top: 476px; left: 28px; }
#Experiment {
  top: 538px;
  left: 28px;
  background: linear-gradient(180deg, var(--lab-primary) 0%, #0f5a94 100%);
  color: #fff;
  border-color: rgba(13, 74, 124, 0.44);
}

#Experiment:hover {
  background: linear-gradient(180deg, var(--lab-primary-hover) 0%, #196ead 100%);
}

#Experiment:active {
  background: linear-gradient(180deg, var(--lab-primary-active) 0%, #0b4775 100%);
}

@media (max-width: 900px) {
  h1 {
    top: 0.75rem;
    width: calc(100vw - 1.5rem);
    padding: 0.85rem 1rem;
  }

  .button_st {
    width: calc(100vw - 1.5rem);
    left: 0.75rem !important;
    min-height: 48px;
    text-align: center;
    font-size: 0.93rem;
  }

  #LEDs_background { top: 96px; }
  #LEDs_obj { top: 154px; }
  #Channel_LEDs_obj { top: 212px; }
  #Absorbing_filter { top: 270px; }
  #Color_filters { top: 328px; }
  #Monochromator { top: 386px; }
  #Shar { top: 444px; }
  #Experiment { top: 502px; }
}