:root {
  --background: #f5f1ea;
  --panel-background: rgba(255, 255, 255, 0.9);
  --panel-border: rgba(0, 0, 0, 0.1);
  --text: #222;
  --muted: #777;
  --accent: #292929;
}

* {
  box-sizing: border-box;
}

html,
body {
  width: 100%;
  height: 100%;
}

body {
  margin: 0;
  overflow: hidden;

  font-family: Arial, Helvetica, sans-serif;

  color: var(--text);
  background: var(--background);
}

button,
input,
select {
  font: inherit;
}

main {
  height: 100vh;

  display: flex;
  flex-direction: column;
}

header {
  flex: 0 0 auto;

  padding: 16px 18px 8px;

  text-align: center;
  pointer-events: none;
}

header h2 {
  margin: 0;
}

#viewer {
  flex: 1 1 auto;

  width: 100%;
  min-height: 0;

  overflow: hidden;
}

#viewer canvas {
  display: block;

  width: 100%;
  height: 100%;

  touch-action: none;
}

/* Bottom controls */

.book-controls {
  flex: 0 0 auto;

  min-height: 66px;

  display: flex;
  align-items: center;
  justify-content: center;

  gap: 10px;

  padding: 10px 350px 10px 18px;

  border-top: 1px solid rgba(0, 0, 0, 0.06);

  background: rgba(255, 255, 255, 0.74);

  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

button,
.small-upload-button {
  border: 0;
  border-radius: 999px;

  color: white;
  background: var(--accent);

  font-weight: 700;
  text-align: center;

  cursor: pointer;
}

button:hover,
.small-upload-button:hover {
  opacity: 0.82;
}

button:disabled {
  cursor: wait;
  opacity: 0.55;
}

.bottom-control {
  min-height: 42px;

  display: inline-flex;
  align-items: center;
  justify-content: center;

  gap: 7px;

  padding: 9px 15px;

  font-size: 14px;
}

.icon-only-control {
  width: 44px;
  padding: 9px;
}

.control-icon {
  width: 20px;
  height: 20px;

  flex: 0 0 auto;

  fill: currentColor;
}

/* Settings panel */

.settings-panel {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 20;

  width: 320px;
  max-height: calc(100vh - 36px);

  padding: 16px;

  overflow-x: hidden;
  overflow-y: auto;

  overscroll-behavior: contain;

  border: 1px solid var(--panel-border);
  border-radius: 20px;

  background: var(--panel-background);

  box-shadow:
    0 16px 50px rgba(0, 0, 0, 0.14),
    inset 0 1px rgba(255, 255, 255, 0.8);

  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);

  transition:
    width 0.2s ease,
    padding 0.2s ease;
}

.settings-panel::-webkit-scrollbar {
  width: 8px;
}

.settings-panel::-webkit-scrollbar-thumb {
  border: 2px solid transparent;
  border-radius: 999px;

  background: rgba(0, 0, 0, 0.2);
  background-clip: padding-box;
}

.settings-panel.collapsed {
  width: auto;
  padding: 11px 12px;

  overflow: hidden;
}

.panel-header {
  position: sticky;
  top: -16px;
  z-index: 3;

  display: flex;
  align-items: center;
  justify-content: space-between;

  gap: 16px;

  margin: -16px -16px 0;
  padding: 16px 16px 10px;

  background: rgba(255, 255, 255, 0.84);

  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.settings-panel.collapsed .panel-header {
  position: static;

  margin: 0;
  padding: 0;

  background: transparent;
}

.panel-header strong {
  font-size: 16px;
}

.panel-header-actions {
  display: flex;
  align-items: center;

  gap: 7px;
}

.panel-header button {
  padding: 7px 12px;

  font-size: 12px;
}

#collapsePanelBtn {
  width: 30px;
  height: 30px;

  display: grid;
  place-items: center;

  padding: 0;

  font-size: 19px;
  line-height: 1;
}

.settings-panel.collapsed #resetCameraBtn {
  display: none;
}

.panel-content {
  margin-top: 8px;
}

.settings-panel.collapsed .panel-content {
  display: none;
}

.control-section {
  padding: 9px 0 15px;
}

.control-section + .control-section {
  border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.section-title {
  margin-bottom: 10px;

  color: var(--muted);

  font-size: 11px;
  font-weight: 800;

  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* Camera */

.camera-slider-row {
  display: grid;
  grid-template-columns: 22px 1fr;
  align-items: center;

  gap: 10px;

  margin-top: 13px;
}

.camera-slider-row label {
  font-size: 15px;
  font-weight: 800;

  text-align: center;
}

.camera-slider-row input[type="range"],
.label-slider-row input[type="range"] {
  width: 100%;
  min-width: 0;

  margin: 0;

  cursor: pointer;
}

/* Selects and sliders */

.select-row,
.label-slider-row {
  display: grid;
  grid-template-columns: 82px 1fr;
  align-items: center;

  gap: 12px;

  margin-top: 12px;
}

.select-row label,
.label-slider-row label {
  font-size: 13px;
  font-weight: 700;
}

.select-row select {
  width: 100%;

  padding: 8px 10px;

  border: 1px solid rgba(0, 0, 0, 0.14);
  border-radius: 10px;

  color: var(--text);
  background: white;

  cursor: pointer;
}

/* Uploads */

.file-upload-row {
  display: flex;
  align-items: center;
  justify-content: space-between;

  gap: 12px;

  margin-top: 11px;
}

.file-upload-row > span {
  font-size: 13px;
  font-weight: 700;
}

.small-upload-button {
  min-width: 80px;

  padding: 7px 12px;

  font-size: 12px;
}

/* Scene */

.scene-controls {
  padding-bottom: 0;
}

.checkbox-row {
  display: flex;
  align-items: center;

  gap: 9px;

  width: fit-content;

  font-size: 14px;
  font-weight: 700;

  cursor: pointer;
}

.checkbox-row input {
  width: 17px;
  height: 17px;

  margin: 0;

  accent-color: var(--accent);
}

.background-color-row {
  display: flex;
  align-items: center;
  justify-content: space-between;

  gap: 12px;

  margin-top: 14px;
}

.background-color-row > label {
  font-size: 13px;
  font-weight: 700;
}

.color-actions {
  display: flex;
  align-items: center;

  gap: 8px;
}

.background-color-row input[type="color"] {
  width: 46px;
  height: 32px;

  padding: 2px;

  border: 1px solid rgba(0, 0, 0, 0.14);
  border-radius: 8px;

  background: transparent;

  cursor: pointer;
}

.small-secondary-button {
  padding: 7px 10px;

  color: var(--text);
  background: rgba(0, 0, 0, 0.07);

  font-size: 11px;
}

.brightness-labels {
  display: flex;
  justify-content: space-between;

  margin: 3px 0 0 94px;

  color: var(--muted);

  font-size: 10px;
}

.secondary-button {
  width: 100%;

  margin-top: 12px;
  padding: 9px 15px;

  color: var(--text);
  background: rgba(0, 0, 0, 0.07);

  font-size: 13px;
}

@media (max-width: 720px) {
  header {
    padding-top: 12px;
  }

  .settings-panel {
    right: 10px;
    bottom: 76px;

    width: min(305px, calc(100vw - 20px));
    max-height: 62vh;
  }

  .settings-panel.collapsed {
    width: auto;
  }

  .book-controls {
    min-height: 66px;

    padding: 10px;
  }
}

.rotation-control {
  display: flex;
  align-items: center;
  gap: 10px;
}

.rotation-control input[type="range"] {
  width: min(320px, 35vw);
}

.rotation-control span {
  min-width: 38px;
  font-size: 13px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}