title: How can I make these two buttons have the same width?
body: <p><a href="https://i.stack.imgur.com/ksyRH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ksyRH.png" alt="enter image description here"></a></p>
  
  <p>I want the login and register buttons to have the same width. I want it to be done using flex or anything similar but do not hardcode the pixels amount.</p>
  
  <p>This is my current JSFiddle, <a href="https://jsfiddle.net/akap9dq0/" rel="nofollow noreferrer">https://jsfiddle.net/akap9dq0/</a>.</p>
  
  <pre><code>&lt;body&gt;
    &lt;div class="container-fluid"&gt;
      &lt;nav class="navbar navbar-default"&gt;
        &lt;div class="navbar-header"&gt;
          &lt;a class="navbar-brand" href="#"&gt;...&lt;/a&gt;
          &lt;button aria-expanded="false" class="collapsed navbar-toggle" data-target="#main_menu" data-toggle="collapse" type="button"&gt;
            &lt;span class="sr-only"&gt;toggle navigation&lt;/span&gt;
            &lt;span class="icon-bar"&gt;&lt;/span&gt;
            &lt;span class="icon-bar"&gt;&lt;/span&gt;
            &lt;span class="icon-bar"&gt;&lt;/span&gt;
          &lt;/button&gt;
        &lt;/div&gt;
        &lt;div class="collapse navbar-collapse" id="main_menu"&gt;
          &lt;form class="navbar-form navbar-right" style="border: none;"&gt;
            &lt;div id="main_menu_container"&gt;
              &lt;div id="main_menu_form_input"&gt;
                &lt;input class="form-control" type="text" name="username" placeholder="User name" style="flex:1;"&gt;
                &lt;input class="form-control" type="password" name="password" placeholder="Password" style="flex:1;"&gt;
              &lt;/div&gt;
              &lt;div id="main_menu_form_buttons"&gt;
                &lt;input class="btn btn-block btn-success" type="submit" style="flex: 1; margin: 0;" value="login"&gt;
                &lt;input class="btn btn-block btn-primary" type="submit" style="flex: 1; margin: 0;" value="register"&gt;
              &lt;/div&gt;
            &lt;/div&gt;
          &lt;/form&gt;
        &lt;/div&gt;
      &lt;/nav&gt;
    &lt;/div&gt;
  &lt;/body&gt;
  </code></pre>