:root {
  --navy: #2c3e50;
  --teal: #1abc9c;
  --gold: #f1c40f;
  --coral: #e74c3c;
  --slate: #556366;
  --softgray: #ecf0f1;
  --white: #ffffff;
  --gray-100: #f7fafc;
  --gray-200: #edf2f7;
  --gray-300: #e2e8f0;
  --max-width: 1280px;
  --radius: 10px;
  --shadow-sm: 0 6px 18px rgba(0, 0, 0, 0.06);
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.06);
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family:
    'Montserrat',
    system-ui,
    -apple-system,
    'Segoe UI',
    Roboto,
    'Helvetica Neue',
    Arial;
  color: var(--navy);
  background: linear-gradient(135deg, #ecf0f1 0%, #d6dbdf 100%);
  padding: 16px;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.6;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 16px;
}

/* Header */
.page-header {
  text-align: center;
  padding: 1rem 0;
}

.header-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 12px;
}

.page-title {
  margin: 0;
  font-size: clamp(24px, 2.6vw, 34px);
  font-weight: 700;
}

@media (max-width: 767px) {
  .header-grid {
    grid-template-columns: 1fr;
    text-align: left;
  }
}

/* Video stage */
.video-stage {
  background: var(--gray-100);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow-sm);
  margin-bottom: 16px;
}

/* Upload area */
.upload-area {
  position: relative;
  border: 2px dashed var(--gray-300);
  border-radius: var(--radius);
  background: var(--white);
  min-height: 260px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 32px;
  text-align: center;
  transition: all 0.2s ease;
}

.upload-area:hover,
.upload-area:focus-within {
  border-color: var(--teal);
  background: rgba(26, 188, 156, 0.04);
}

.upload-input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
}

.upload-label {
  pointer-events: none;
  font-size: 17px;
  font-weight: 600;
  color: var(--slate);
}

/* Video */
.video-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(280px, 1fr);
  gap: 16px;
  align-items: start;
}

.video-column {
  display: flex;
  flex-direction: column;
  gap: 14px;
  min-width: 0;
}

.controls-column {
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-width: 0;
}

@media (max-width: 900px) {
  .video-wrap {
    grid-template-columns: 1fr;
  }
}

.video-viewport {
  position: relative;
  width: 100%;
  max-height: 70vh;
  overflow: auto;
  background: #000;
  border-radius: 8px;
  box-shadow: var(--shadow-xs);
}

.video-frame {
  position: relative;
  width: calc(100% * var(--zoom, 1));
  background: #000;
  line-height: 0;
}

.video {
  width: 100%;
  height: auto;
  display: block;
  background: #000;
}

.zoom-controls {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--white);
  border-radius: 8px;
  padding: 10px 14px;
  box-shadow: var(--shadow-xs);
}

.zoom-slider {
  flex: 1;
  min-width: 120px;
}

.zoom-readout {
  font-size: 14px;
  font-weight: 700;
  color: var(--navy);
  font-variant-numeric: tabular-nums;
  min-width: 44px;
  text-align: right;
}

.zoom-reset-btn {
  padding: 8px 14px;
  font-size: 14px;
}

.overlay-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.video-frame.has-active-tool .overlay-canvas {
  pointer-events: auto;
  cursor: crosshair;
}

/* Tool row */
.tool-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  background: var(--white);
  border-radius: 8px;
  padding: 8px;
  box-shadow: var(--shadow-xs);
}

.tool-btn {
  flex: 1 1 auto;
  min-width: 96px;
  background: var(--white);
  color: var(--slate);
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  padding: 10px 12px;
  font-family: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.tool-btn:hover:not(:disabled) {
  border-color: var(--teal);
  color: var(--navy);
}

.tool-btn.active {
  background: var(--teal);
  border-color: var(--teal);
  color: var(--white);
}

.tool-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

/* Frame counter */
.frame-counter {
  display: inline-flex;
  flex-direction: column;
  gap: 2px;
  font-variant-numeric: tabular-nums;
}

/* Calibration readout */
.calibration-readout {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--white);
  border-radius: 8px;
  padding: 10px 14px;
  box-shadow: var(--shadow-xs);
  font-variant-numeric: tabular-nums;
}

.calibration-label {
  font-size: 12px;
  color: var(--slate);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}

.calibration-value {
  font-size: 16px;
  font-weight: 700;
  color: var(--navy);
}

.calibration-value.not-calibrated {
  color: var(--slate);
  font-style: italic;
  font-weight: 600;
}

/* Tool panel */
.tool-panel {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.tool-panel:empty,
.tool-panel:not(:has(.tool-panel-section:not([hidden]))) {
  display: none;
}

.tool-panel-section {
  background: var(--white);
  border-radius: 8px;
  padding: 12px 14px;
  box-shadow: var(--shadow-xs);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.panel-hint {
  margin: 0;
  font-size: 14px;
  color: var(--slate);
  flex: 1 1 200px;
}

.calibrate-input-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  width: 100%;
}

.calibrate-input-label {
  font-size: 14px;
  color: var(--navy);
  font-weight: 600;
}

/* Ball selector */
.ball-selector {
  display: inline-flex;
  border-radius: 6px;
  overflow: hidden;
  border: 1px solid var(--gray-300);
}

.ball-btn {
  background: var(--white);
  color: var(--slate);
  border: 0;
  padding: 8px 14px;
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  border-right: 1px solid var(--gray-300);
}

.ball-btn:last-child {
  border-right: 0;
}

.ball-btn.active.ball-a {
  background: var(--teal);
  color: var(--white);
}

.ball-btn.active.ball-b {
  background: var(--gold);
  color: var(--navy);
}

/* Measurements panel */
.panel {
  background: var(--white);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow-sm);
  margin-bottom: 16px;
}

.measurements-title {
  margin: 0 0 14px;
  font-size: 18px;
  font-weight: 700;
}

.measurements-body {
  display: grid;
  gap: 14px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.measurement-card {
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  padding: 14px;
  background: var(--gray-100);
}

.measurement-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 10px;
  font-size: 15px;
}

.ball-dot {
  display: inline-block;
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.ball-dot.ball-a {
  background: var(--teal);
}

.ball-dot.ball-b {
  background: var(--gold);
}

.measurement-list {
  margin: 0;
  display: grid;
  gap: 8px;
}

.measurement-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  border-bottom: 1px dashed var(--gray-300);
  padding-bottom: 6px;
}

.measurement-row:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.measurement-row dt {
  margin: 0;
  font-size: 14px;
  color: var(--slate);
}

.measurement-row dd {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: var(--navy);
  font-variant-numeric: tabular-nums;
}

.measurement-card.angle-card {
  border-color: var(--gray-300);
  background: var(--white);
}

.angle-pair {
  font-size: 14px;
  color: var(--slate);
  margin-bottom: 4px;
}

.angle-value {
  font-size: 22px;
  font-weight: 700;
  color: var(--navy);
  font-variant-numeric: tabular-nums;
}

/* Results table */
.results-title {
  margin: 0 0 6px;
  font-size: 18px;
  font-weight: 700;
}

.results-hint {
  margin: 0 0 14px;
  font-size: 14px;
  color: var(--slate);
}

.mass-inputs {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  margin-bottom: 16px;
}

.mass-input {
  background: var(--gray-100);
  border-radius: 8px;
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.mass-input-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 600;
  color: var(--navy);
}

.mass-input-field {
  display: flex;
  align-items: center;
  gap: 8px;
}

.mass-input-field .cell-input {
  flex: 1;
}

.mass-input-field .unit {
  font-size: 14px;
  color: var(--slate);
  font-weight: 600;
}

.table-wrap {
  overflow-x: auto;
}

.results-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
  font-variant-numeric: tabular-nums;
}

.results-table th,
.results-table td {
  padding: 8px 10px;
  text-align: left;
  border-bottom: 1px solid var(--gray-200);
}

.results-table thead th {
  background: var(--gray-100);
  font-weight: 700;
  color: var(--navy);
  border-bottom: 2px solid var(--gray-300);
  font-size: 14px;
}

.cell-input {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  font: inherit;
  font-size: 15px;
  font-variant-numeric: tabular-nums;
  background: var(--white);
  color: var(--navy);
}

.cell-input:focus {
  outline: none;
  border-color: var(--teal);
  box-shadow: 0 0 0 3px rgba(26, 188, 156, 0.15);
}

.cell-input[type='number'] {
  appearance: textfield;
  -moz-appearance: textfield;
  text-align: right;
}

.cell-input[type='number']::-webkit-outer-spin-button,
.cell-input[type='number']::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.panel-footer {
  margin-top: 12px;
  display: flex;
  justify-content: flex-end;
}

/* Collapsible (instructions / investigation) */
.collapsible {
  width: 100%;
}

.collapsible-summary {
  cursor: pointer;
  font-size: 18px;
  font-weight: 700;
  color: var(--navy);
  list-style: none;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 2px 0;
}

.collapsible-summary::-webkit-details-marker {
  display: none;
}

.collapsible-summary::before {
  content: '\203A';
  display: inline-block;
  font-size: 22px;
  line-height: 1;
  color: var(--slate);
  transition: transform 0.2s ease;
  transform: translateY(-1px);
  width: 14px;
  text-align: center;
}

.collapsible[open] > .collapsible-summary::before {
  transform: rotate(90deg) translateX(-1px);
}

.collapsible-summary:focus-visible {
  outline: 3px solid rgba(26, 188, 156, 0.18);
  outline-offset: 2px;
  border-radius: 4px;
}

.instructions-list,
.investigation-list {
  margin: 12px 0 0;
  padding-left: 22px;
  font-size: 15px;
  color: var(--navy);
}

.instructions-list li,
.investigation-list li {
  margin-bottom: 8px;
  line-height: 1.55;
}

.investigation-intro {
  margin: 12px 0 8px;
  font-size: 14px;
  color: var(--slate);
}

/* Measurement notices and placeholders */
.measurement-notice {
  grid-column: 1 / -1;
  background: rgba(241, 196, 15, 0.12);
  border: 1px solid rgba(241, 196, 15, 0.45);
  color: var(--navy);
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 14px;
}

.measurement-card.placeholder {
  background: var(--white);
  border-style: dashed;
}

.measurement-empty {
  margin: 0;
  font-size: 14px;
  color: var(--slate);
  font-style: italic;
}

.video-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  background: var(--white);
  border-radius: 8px;
  padding: 12px 14px;
  box-shadow: var(--shadow-xs);
}

.delete-video-btn {
  margin-left: auto;
}

.playback-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  background: var(--white);
  border-radius: 8px;
  padding: 12px 14px;
  box-shadow: var(--shadow-xs);
}

.playback-meta .time-readouts {
  margin-left: auto;
}

.control-field {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.control-label {
  font-size: 13px;
  color: var(--slate);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}

.control-input {
  width: 90px;
  padding: 8px 10px;
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  font: inherit;
  font-size: 15px;
  text-align: right;
  font-variant-numeric: tabular-nums;
  background: var(--white);
  color: var(--navy);
}

.control-input:focus {
  outline: none;
  border-color: var(--teal);
  box-shadow: 0 0 0 3px rgba(26, 188, 156, 0.15);
}

.control-input::-webkit-outer-spin-button,
.control-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.control-input[type='number'] {
  appearance: textfield;
  -moz-appearance: textfield;
}

.time-readouts {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-left: auto;
  font-variant-numeric: tabular-nums;
}

.time-readout {
  display: inline-flex;
  flex-direction: column;
  gap: 2px;
}

.time-label {
  font-size: 12px;
  color: var(--slate);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}

.time-value {
  font-size: 18px;
  font-weight: 700;
  color: var(--navy);
}

.time-sep {
  font-size: 18px;
  color: var(--gray-300);
  font-weight: 700;
  align-self: center;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 12px 18px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 16px;
  font-family: inherit;
  text-align: center;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.2s ease;
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.teal-btn {
  background: var(--teal);
  color: var(--white);
}

.teal-btn:hover:not(:disabled) {
  background: #17a589;
  transform: translateY(-1px);
}

.navy-btn {
  background: var(--navy);
  color: var(--white);
}

.navy-btn:hover:not(:disabled) {
  background: #1f2d3a;
  transform: translateY(-1px);
}

.coral-btn {
  background: var(--coral);
  color: var(--white);
}

.coral-btn:hover:not(:disabled) {
  background: #d9382b;
  transform: translateY(-1px);
}

/* Main content area */
.main-content {
  min-height: 40px;
}

a:focus,
button:focus,
input:focus {
  outline: 3px solid rgba(26, 188, 156, 0.18);
  outline-offset: 2px;
}

/* Footer */
.site-footer {
  background: var(--navy);
  color: #fff;
  text-align: center;
  padding: 16px;
  font-size: 0.8rem;
  margin: 32px -16px -16px;
}

.site-footer p {
  margin: 0;
}

@media (max-width: 600px) {
  .time-readouts {
    margin-left: 0;
    width: 100%;
    justify-content: flex-start;
  }
}