zulip/static/templates/stream_settings/stream_settings_overlay.hbs

<div id="subscription_overlay" class="overlay new-style" data-overlay="subscriptions">
    <div class="flex overlay-content">
        <div class="subscriptions-container modal-bg">
            <div class="subscriptions-header">
                <div class="fa fa-chevron-left"></div>
                <span class="subscriptions-title">{{t 'Streams' }}</span>
                <div class="exit">
                    <span class="exit-sign">&times;</span>
                </div>
            </div>
            <div class="left">
                <div class="search-container">
                    <div id="add_new_subscription">
                        {{#if can_create_streams}}
                        <button class="create_stream_button create_stream_plus_button tippy-zulip-tooltip" data-tippy-content="{{t 'Create new stream' }} (n)" data-tippy-placement="bottom">+</button>
                        {{/if}}
                        <div class="float-clear"></div>
                    </div>
                </div>
                <div class="input-append stream_name_search_section" id="stream_filter">
                    <input type="text" name="stream_name" id="search_stream_name" autocomplete="off"
                      placeholder="{{t 'Filter streams' }}" value=""/>
                    <button type="button" class="btn clear_search_button" id="clear_search_stream_name">
                        <i class="fa fa-remove" aria-hidden="true"></i>
                    </button>
                </div>
                <div class="streams-list" data-simplebar>
                </div>
            </div>
            <div class="right">
                <div class="display-type">
                    <div id="stream_settings_title" class="stream-info-title">{{t 'Stream settings' }}</div>
                </div>
                <div class="nothing-selected">
                    {{#if can_create_streams}}
                    <button type="button" class="create_stream_button animated-purple-button">{{t 'Create stream' }}</button>
                    <span>
                        {{#tr}}
                            First time? Read our <z-link>guidelines</z-link> for creating and naming streams.
                            {{#*inline "z-link"}}<a href="/help/getting-your-organization-started-with-zulip#create-streams" target="_blank" rel="noopener noreferrer">{{> @partial-block}}</a>{{/inline}}
                        {{/tr}}
                    </span>
                    {{/if}}
                </div>
                <div id="stream_settings" class="settings" data-simplebar data-simplebar-auto-hide="false">
                    {{!-- edit stream here --}}
                </div>
                {{> stream_creation_form }}
            </div>
        </div>
    </div>
</div>