chromium/chrome/browser/resources/omnibox_popup/app.html

<style>
  :host {
    --cr-searchbox-min-width: 75%;
    --cr-searchbox-width: 100%;
    font-size: 14.6px; /* closely resembles the omnibox input font size. */
    /* Colors used in the cr-searchbox results dropdown */
    --color-searchbox-answer-icon-background: var(--color-omnibox-answer-icon-g-m3-background);
    --color-searchbox-answer-icon-foreground: var(--color-omnibox-answer-icon-g-m3-foreground);
    --color-searchbox-results-action-chip-focus-outline: var(--color-omnibox-results-button-icon-selected);
    --color-searchbox-results-action-chip-icon: var(--color-omnibox-results-button-icon);
    --color-searchbox-results-action-chip: var(--color-omnibox-results-button-border);
    --color-searchbox-results-background-hovered: var(--color-omnibox-results-background-hovered);
    --color-searchbox-results-background: var(--color-omnibox-results-background);
    /* TODO(b/40251392): Replace hardcoded color below with a color token. */
    --color-searchbox-results-button-hover: #202124ff;
    --color-searchbox-results-dim-selected: var(--color-omnibox-result-text-dimmed-selected);
    --color-searchbox-results-focus-indicator: var(--color-omnibox-results-focus-indicator);
    --color-searchbox-results-foreground-dimmed: var(--color-omnibox-results-text-dimmed);
    --color-searchbox-results-foreground: var(--color-omnibox-text);
    --color-searchbox-results-icon-focused-outline: var(--color-omnibox-results-focus-indicator);
    --color-searchbox-results-icon-selected: var(--color-omnibox-results-icon-selected);
    --color-searchbox-results-icon: var(--color-omnibox-results-icon);
    --color-searchbox-results-url-selected: var(--color-omnibox-results-url-selected);
    --color-searchbox-results-url: var(--color-omnibox-results-url);
    --color-searchbox-search-icon-background: var(--color-omnibox-results-icon);
  }

  /**
   * Show the secondary side if it can be shown and is currently available to be
   * shown.
   */
  :host([can-show-secondary-side][has-secondary-side]) {
    --cr-searchbox-secondary-side-display: block;
  }
</style>
<cr-searchbox-dropdown id="matches" result="[[result_]]"
    can-show-secondary-side="[[canShowSecondarySide]]"
    has-secondary-side="{{hasSecondarySide}}"
    on-dom-change="onResultRepaint_">
</cr-searchbox-dropdown>