desktop/src/zen/split-view/zen-split-group.inc.css

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

tab-group[split-view-group] {
  display: block;

  @media (prefers-reduced-motion: no-preference) {
    transition: var(--zen-tabbox-element-indent-transition);

    #tabbrowser-tabs[movingtab] & {
      transition: var(--tab-dragover-transition), var(--zen-tabbox-element-indent-transition);
    }
  }
  --zen-split-view-active-tab-bg: color-mix(
    in srgb,
    var(--zen-toolbar-element-bg),
    transparent 40%
  );

  --tab-collapsed-background-width: none;

  :root[zen-sidebar-expanded='true'] & {
    margin-inline-start: var(--zen-folder-indent) !important;
  }

  & .tab-group-label {
    height: 100% !important;
  }

  & .tab-group-container {
    display: flex;
    flex-wrap: nowrap;
    align-items: center;

    border-radius: var(--border-radius-medium);
    padding: 0 2px;
    margin-inline: var(--tab-block-margin);
    margin-block: var(--tab-block-margin);
    min-height: var(--tab-min-height);
    outline: var(--tab-outline);
    outline-offset: var(--tab-outline-offset);
    outline-color: var(--tab-selected-outline-color);
    transition: scale 0.1s ease;
    margin-inline: 2px !important;

    :root:not([zen-sidebar-expanded='true']) & {
      padding: 0;
      --tab-collapsed-width: 38px;
      overflow: clip;
      --tab-min-width: 34px;
      outline: 2px solid var(--zen-colors-border-contrast);
      outline-offset: -2px;
    }

    & > .tabbrowser-tab {
      --tab-selected-bgcolor: var(--zen-split-view-active-tab-bg);
      --tab-hover-background-color: transparent;
      --tab-selected-shadow: none;
      --border-radius-medium: var(--tab-border-radius);
      --zen-active-tab-scale: 1;
      --zen-folder-indent: 0 !important;

      :root[zen-sidebar-expanded='true'] & {
        --tab-min-height: 28px;
      }

      container-type: inline-size;
      container-name: browser-tab;

      flex: 1 !important;
      padding-inline: 2px !important;
      overflow: clip;

      &:not(:last-child)::after {
        content: '';
        width: 1px;
        height: 16px;
        background-color: light-dark(rgba(0, 0, 0, 0.1), rgba(255, 255, 255, 0.2));
        position: absolute;
        right: 0;
        top: 50%;
        transform: translateY(-50%);
      }

      :root:not([zen-sidebar-expanded='true']) &:not(:last-child)::after {
        width: 16px;
        height: 1px;
        top: auto;
        bottom: 0;
        right: 50%;
        transform: translateX(50%);
      }

      & .tab-content {
        min-width: 0;
        padding: 0 4px !important;
        :root[zen-sidebar-expanded='true'] & {
          justify-content: unset !important;
        }
      }
    }

    &:has(> tab:is([visuallyselected], [multiselected])) {
      background-color: var(--tab-selected-bgcolor);
      box-shadow: var(--tab-selected-shadow);

      & > .tabbrowser-tab {
        --tab-hover-background-color: var(--zen-split-view-active-tab-bg);
        & .tab-background {
          background-color: var(--zen-split-view-active-tab-bg) !important;
        }

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

    &:active {
      scale: var(--zen-active-tab-scale);
    }

    &:hover {
      background-color: var(--zen-toolbar-element-bg);
    }

    & .tab-close-button,
    & .tab-reset-button {
      display: none !important;
    }

    @container browser-tab (min-width: 70px) {
      :root[zen-sidebar-expanded='true'] &:hover > .tabbrowser-tab:not([pinned]:not([pending])) .tab-close-button {
        display: block !important;

        /* This is from Firefox itself, but we need to always override it */
        margin-inline-end: 0 !important;
      }
    }

    @media (prefers-reduced-motion: no-preference) {
      #tabbrowser-tabs[movingtab] & {
        transition: var(--tab-dragover-transition);
      }
    }
  }
}

:root:not([zen-sidebar-expanded='true']) {
  tab-group .tab-group-container {
    flex-direction: column;
  }

  tab-group[split-view-group] {
    min-width: 100%;
  }
}

tab-group[split-view-group] .tabbrowser-tab {
  width: 100%;
  max-width: unset;
}

tab-group[split-view-group] .tab-group-label-container {
  position: absolute;
  width: -moz-available;
  height: 36px;
  visibility: hidden;
  padding: 0 !important;
  margin: 2px 0 0 0 !important;
}

tab-group[split-view-group] .tab-close-button {
  display: block;
  visibility: visible;
}

tab-group[split-view-group] .tab-group-line {
  display: none;
  background: transparent;
}