.panel {
  position: relative;
  display: flex;
  flex-direction: column;
  background-color: $fallback--bg;
  background-color: var(--bg, $fallback--bg);

  &::after,
  & {
    border-radius: $fallback--panelRadius;
    border-radius: var(--panelRadius, $fallback--panelRadius);
  }

  &::after {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 5;
    box-shadow: 1px 1px 4px rgba(0, 0, 0, 0.6);
    box-shadow: var(--panelShadow);
    pointer-events: none;
  }
}

.panel-body {
  padding: var(--panel-body-padding, 0);

  &:empty::before {
    content: "¯\\_(ツ)_/¯"; // Could use words but it'd require translations
    display: block;
    margin: 1em;
    text-align: center;
  }

  > p {
    line-height: 1.3;
    padding: 1em;
    margin: 0;
  }
}

.panel-heading,
.panel-footer {
  --panel-heading-height-padding: 0.6em;
  --__panel-heading-height: 3.2em;
  --__panel-heading-height-inner: calc(var(--__panel-heading-height) - 2 * var(--panel-heading-height-padding));

  position: relative;
  box-sizing: border-box;
  display: grid;
  grid-auto-flow: column;
  grid-template-columns: minmax(50%, 1fr);
  grid-auto-columns: auto;
  grid-column-gap: 0.5em;
  flex: none;
  background-size: cover;
  padding: 0.6em;
  height: var(--__panel-heading-height);
  line-height: var(--__panel-heading-height-inner);
  z-index: 4;

  &.-flexible-height {
    --__panel-heading-height: auto;

    &::after,
    &::before {
      display: none;
    }
  }

  &.-stub {
    &,
    &::after {
      border-radius: $fallback--panelRadius;
      border-radius: var(--panelRadius, $fallback--panelRadius);
    }
  }

  &.-sticky {
    position: sticky;
    top: var(--navbar-height);
  }

  &::after,
  &::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    pointer-events: none;
  }

  .title {
    font-size: 1.3em;
  }

  .alert {
    white-space: nowrap;
    text-overflow: ellipsis;
    overflow-x: hidden;
  }

  &:not(.-flexible-height) {
    > .button-default,
    > .alert {
      height: var(--__panel-heading-height-inner);
      min-height: 0;
      box-sizing: border-box;
      margin: 0;
      min-width: 1px;
      padding-top: 0;
      padding-bottom: 0;
      align-self: stretch;
    }
  }
}

// TODO Should refactor panels into separate component and utilize slots

.panel-heading {
  border-radius: $fallback--panelRadius $fallback--panelRadius 0 0;
  border-radius: var(--panelRadius, $fallback--panelRadius) var(--panelRadius, $fallback--panelRadius) 0 0;
  border-width: 0 0 1px 0;
  align-items: start;
  // panel theme
  color: var(--panelText);
  background-color: $fallback--bg;
  background-color: var(--bg, $fallback--bg);
  // hotfix for misplaced timeline menu/filter popover layer
  z-index: 5;

  &::after {
    background-color: $fallback--fg;
    background-color: var(--panel, $fallback--fg);
    z-index: -2;
    border-radius: $fallback--panelRadius $fallback--panelRadius 0 0;
    border-radius: var(--panelRadius, $fallback--panelRadius) var(--panelRadius, $fallback--panelRadius) 0 0;
    box-shadow: var(--panelHeaderShadow);
  }

  a,
  .-link {
    color: $fallback--link;
    color: var(--panelLink, $fallback--link);
  }

  .faint {
    background-color: transparent;
    color: $fallback--faint;
    color: var(--panelFaint, $fallback--faint);
  }

  .faint-link {
    color: $fallback--faint;
    color: var(--faintLink, $fallback--faint);
  }

  &:not(.-flexible-height) {
    > .button-default {
      flex-shrink: 0;

      &,
      i[class*=icon-] {
        color: $fallback--text;
        color: var(--btnPanelText, $fallback--text);
      }

      &:active {
        background-color: $fallback--fg;
        background-color: var(--btnPressedPanel, $fallback--fg);
        color: $fallback--text;
        color: var(--btnPressedPanelText, $fallback--text);
      }

      &:disabled {
        color: $fallback--text;
        color: var(--btnDisabledPanelText, $fallback--text);
      }

      &.toggled {
        color: $fallback--text;
        color: var(--btnToggledPanelText, $fallback--text);
      }
    }
  }
}

.panel-footer {
  border-radius: 0 0 $fallback--panelRadius $fallback--panelRadius;
  border-radius: 0 0 var(--panelRadius, $fallback--panelRadius) var(--panelRadius, $fallback--panelRadius);
  align-items: center;
  border-width: 1px 0 0 0;
  border-style: solid;
  border-color: var(--border, $fallback--border);
}