breadcrumb-the-shire/web/css/components/app-tabs.css

@layer components {
  /* Tab navigation — scrollable strip with chevron overflow, active/invalid states, no-JS fallback. */
  .app-tabs {
    display: flex;
    flex-direction: column;
    gap: var(--app-spacing);
  }

  /* No-JS fallback: show only first tab panel. */
  html.no-js [data-tabs] [data-tab-panel] {
    display: none;
  }

  html.no-js [data-tabs] [data-tab-panel]:first-of-type {
    display: block;
  }

  /* JS mode: keep panels hidden until tab init completed (prevents flash). */
  html.js [data-tabs]:not([data-tabs-ready="1"]) [data-tab-panel] {
    display: none !important;
  }

  /* ------------------------------------------------------------------ */
  /*  Tab nav wrapper — holds optional chevron buttons + scrollable nav */
  /* ------------------------------------------------------------------ */
  .app-tabs-nav-wrap {
    position: relative;
    display: flex;
    align-items: stretch;
    border-bottom: 1px solid var(--tabs-border);
  }

  /* Chevron scroll buttons — ghost icons, visible only on overflow.
     Reset shell-level button custom properties so the global button
     styles (app-shell.css) do not bleed through. */
  .app-tabs-nav-wrap > .app-tabs-chevron {
    --app-background-color: transparent;
    --app-border-color: transparent;
    --app-color: var(--tabs-muted);
    --app-box-shadow: none;
    flex: 0 0 auto;
    display: none;
    align-items: center;
    justify-content: center;
    border: none;
    border-radius: 50%;
    background: transparent;
    color: var(--tabs-muted);
    font-size: var(--text-xs);
    line-height: 1;
    width: 24px;
    height: 24px;
    padding: 0;
    box-shadow: none;
    cursor: pointer;
    z-index: 2;
    margin-block: auto;
    transition:
      background-color var(--app-transition),
      color var(--app-transition),
      opacity var(--app-transition);
  }

  .app-tabs-nav-wrap > .app-tabs-chevron:hover,
  .app-tabs-nav-wrap > .app-tabs-chevron:focus-visible {
    --app-background-color: color-mix(in srgb, var(--app-contrast) 8%, transparent);
    --app-border-color: transparent;
    --app-color: var(--app-contrast);
    --app-box-shadow: none;
    background: color-mix(in srgb, var(--app-contrast) 8%, transparent);
    color: var(--app-contrast);
  }

  .app-tabs-nav-wrap > .app-tabs-chevron[disabled] {
    opacity: 0;
    cursor: default;
    pointer-events: none;
  }

  .app-tabs-nav-wrap > .app-tabs-chevron--start {
    order: -1;
    margin-inline-end: 2px;
  }

  .app-tabs-nav-wrap > .app-tabs-chevron--end {
    order: 1;
    margin-inline-start: 2px;
  }

  /* Show chevrons when overflow is detected */
  .app-tabs-nav-wrap.has-overflow > .app-tabs-chevron {
    display: flex;
  }

  /* Gradient fade masks — only rendered when the corresponding chevron is visible */
  .app-tabs-nav-wrap.has-overflow:not(.at-start)::before,
  .app-tabs-nav-wrap.has-overflow:not(.at-end)::after {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    width: 32px;
    pointer-events: none;
    z-index: 1;
  }

  .app-tabs-nav-wrap.has-overflow:not(.at-start)::before {
    left: 24px;
    background: linear-gradient(to right, var(--app-card-background-color, var(--app-background-color)), transparent);
  }

  .app-tabs-nav-wrap.has-overflow:not(.at-end)::after {
    right: 24px;
    background: linear-gradient(to left, var(--app-card-background-color, var(--app-background-color)), transparent);
  }

  /* ------------------------------------------------------------------ */
  /*  The scrollable tab strip                                          */
  /* ------------------------------------------------------------------ */
  .app-tabs-nav {
    display: flex;
    border-bottom: 1px solid var(--tabs-border); /* No-JS fallback border */
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    padding-block-start: 2px;
    padding-left: 2px;
    white-space: nowrap;
    flex: 1 1 0%;
    scroll-behavior: smooth;
  }

  /* When wrapped by JS, the wrapper owns the border */
  .app-tabs-nav-wrap > .app-tabs-nav {
    border-bottom: none;
  }

  /* When JS is active: hide the native scrollbar (chevrons take over) */
  html.js .app-tabs-nav {
    scrollbar-width: none; /* Firefox */
  }

  html.js .app-tabs-nav::-webkit-scrollbar {
    display: none; /* Chrome / Safari / Edge */
  }

  .app-tabs-nav button,
  .app-tabs-nav a {
    background: transparent;
    border: 0;
    padding: 5px 10px 5px 10px;
    color: var(--tabs-muted) !important;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    text-decoration: none;
    border-radius: 0;
    margin-bottom: 0;
  }

  .app-tabs-nav button:hover,
  .app-tabs-nav button:focus-visible,
  .app-tabs-nav a:hover,
  .app-tabs-nav a:focus-visible {
    --app-color: inherit;
    color: var(--app-color) !important;
  }

  .app-tabs-nav button.is-active,
  .app-tabs-nav a.is-active {
    --app-color: inherit;
    color: var(--app-color) !important;
    border-color: var(--tabs-active);
  }

  .app-tabs-nav button.has-invalid,
  .app-tabs-nav a.has-invalid {
    color: var(--app-danger, #dc3545) !important;
  }

  [data-tab-panel][hidden] {
    display: none;
  }

  html.js [data-tabs][data-tabs-ready="1"] [data-tab-panel]:not([hidden]) {
    display: block;
  }

  /* Safety fallback when JS is available but the ready marker is missing. */
  html:not(.no-js) [data-tabs] [data-tab-panel]:not([hidden]) {
    display: block;
  }
}