将左:0；和右:0；添加到中。粘头会解决您的问题吗？ 我希望我能理解你的问题。

.sticky-header {
  position: fixed;
  top: 0;
  left: 0;  /* Add this line */
  right: 0;  /* Add this line */
  z-index: 10000;
  background-color: #ffffff;
}

null

$(document).ready(function() {

  $(window).scroll(function() {
    console.log($(window).scrollTop())
    if ($(window).scrollTop() > 180) {
      $('.menu-container').addClass('sticky-header');
    }
    if ($(window).scrollTop() < 181) {
      $('.menu-container').removeClass('sticky-header');
    }
  });
});

body {
  background-color: #ccc;
}


/* Navigation */

#style-2-top-bar {
  background-color: #ffffff;
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
  padding-top: 18px;
}

#logo a img {
  padding-bottom: 10px;
}


/* header details */

.details-block .block .media i {
  background-color: #0087be;
  color: #fff;
  padding-top: 10px;
  padding-bottom: 10px;
  padding-left: 13px;
  font-size: 18px;
  height: 40px;
  line-height: 20px;
  width: 40px;
  border-radius: 10%;
}

.details-block .block .media .media-body h5 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 0;
}

.details-block .block .media .media-body p {
  font-size: 13px;
}

.details-block .block:not(:last-child) {
  margin-right: 20px;
}


/* Main navigation */

#main-nav-wrapper {
  height: 50px;
  background-color: #fff;
}

#main-nav-wrapper .header-main-section {
  position: relative;
}

.sticky-header {
  position: fixed;
  top: 0;
  left: 0;  /* Add this line */
  right: 0;  /* Add this line */
  z-index: 10000;
  background-color: #ffffff;
}

#main-nav-wrapper .header-main-section .menu {
  float: left;
  margin-top: 10px;
  margin-left: -50px;
}

.menu li {
  list-style: none;
  display: inline-block;
}

.menu li a {
  color: #2b2b2b;
  text-transform: uppercase;
  text-decoration: none;
  padding: 0 10px;
  transition: .4s;
  font-size: 14px;
  font-weight: 600;
}

.show-menu-btn,
.hide-menu-btn {
  transition: .4s;
  font-size: 30px;
  cursor: pointer;
  display: none;
}

.show-menu-btn {
  float: right;
}

.show-menu-btn i {
  line-height: 80px;
}

.menu a:hover,
.show-menu-btn:hover,
.hide-menu-btn:hover {
  color: #3498db;
}

#chk {
  position: absolute;
  visibility: hidden;
  z-index: -1111;
}


/* Drop down menu style */

#main-nav-wrapper .header-main-section ul ul {
  position: absolute;
  top: 50px;
  background: #ffffff;
  border-top-width: 3px;
  border-bottom-width: 0px;
  border-left-width: 0px;
  border-right-width: 0px;
  border-style: solid;
  border-color: #0087be;
  -webkit-box-shadow: 0 6px 12px rgba(0, 0, 0, .175);
  box-shadow: 0 6px 12px rgba(0, 0, 0, .175);
  opacity: 0;
  visibility: hidden;
  transform: scaleY(0);
  -webkit-transform: scaleY(0);
  -moz-transform: scaleY(0);
  -ms-transform: scaleY(0);
  -o-transform: scaleY(0);
  transform-origin: center top 0;
  -webkit-transform-origin: center top 0;
  -moz-transform-origin: center top 0;
  -ms-transform-origin: center top 0;
  -o-transform-origin: center top 0;
  transition: all 0.3s ease-in-out 0s;
  -webkit-transition: all 0.3s ease-in-out 0s;
  -moz-transition: all 0.3s ease-in-out 0s;
  -ms-transition: all 0.3s ease-in-out 0s;
  -o-transition: all 0.3s ease-in-out 0s;
  padding: 0;
  z-index: 1000;
}

#main-nav-wrapper .header-main-section ul li:hover>ul {
  opacity: 1;
  visibility: visible;
  transform: scaleY(1);
  -moz-transform-origin: center top 0;
  -webkit-transform: scaleY(1);
  -moz-transform: scaleY(1);
  -ms-transform: scaleY(1);
  -o-transform: scaleY(1);
}

#main-nav-wrapper .header-main-section ul ul li {
  position: relative;
  margin: 0px;
  width: 180px;
  float: none;
  display: block;
  line-height: 50px;
}

#main-nav-wrapper .header-main-section ul ul li:not(:last-child) {
  border-bottom: 1px solid rgba(57, 81, 104, .2);
}

#main-nav-wrapper .header-main-section ul ul li a {
  display: block;
  font-size: 12px;
}


/* Content */

#hero {
  background: url('../images/medicalbg-2.jpg') rgba(0, 0, 0, .8);
  padding-top: 50px;
  padding-bottom: 50px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.0-2/css/all.min.css" rel="stylesheet" />
<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.min.css" rel="stylesheet" />

<header id="style-2-header">

  <div id="style-2-top-bar">

    <div class="container">

      <div class="row">

        <div class="col-lg-3">

          <div id="logo">
            <a href="">
              <img class="img-fluid" src="https://dailyenglishtests.com/logo-dark.png" width="227" height="50">
            </a>
          </div>

        </div>

        <div class="col-lg-9">

          <div class="details-block d-flex justify-content-end">

            <div class="block">
              <div class="media">
                <i class="fas fa-map-marker-alt mr-2"></i>
                <div class="media-body">
                  <h5>One Canada Square,</h5>
                  <p>Canary Wharf, United Kingdom.</p>
                </div>
              </div>
            </div>

            <div class="block">
              <div class="media">
                <i class="far fa-clock mr-2"></i>
                <div class="media-body">
                  <h5>Mon-Fri: 9am to 5pm</h5>
                  <p>Saturday/Sunday: Closed</p>
                </div>
              </div>
            </div>

            <div class="block">
              <div class="media">
                <i class="fas fa-headset mr-2"></i>
                <div class="media-body">
                  <h5>+12 123 456 789</h5>
                  <p><a href="mailto:info@yoursite.com">info@yoursite.com</a></p>
                </div>
              </div>
            </div>

          </div>

        </div>

      </div>

    </div>
    <!-- End .container -->

  </div>
  <!-- End #header-logo-bar -->

  <div id="main-nav-wrapper">

    <div class="header-main-section">

      <div class="menu-container">
        <div class="container">
          <input type="checkbox" id="chk">
          <label for="chk" class="show-menu-btn">
						<i class="fas fa-ellipsis-h"></i>
					</label>

          <ul class="menu">
            <li><a href="#">Home</a></li>
            <li><a href="#">Blog</a></li>
            <li>
              <a href="#" aria-haspopup="true"><i class="fas fa-chevron-down"></i> My Account</a>
              <ul>
                <li><a href="#"><i class="fas fa-user-cog"></i> Dashboard</a></li>
                <li><a href="#"><i class="fas fa-user-md"></i> Profile</a></li>
                <li><a href="#"><i class="fas fa-sign-out-alt"></i> Sections</a></li>
                <li><a href="#"><i class="fas fa-sign-out-alt"></i> Change Email</a></li>
              </ul>
            </li>

            <label for="chk" class="hide-menu-btn">
							<i class="fas fa-times"></i>
						</label>
          </ul>
        </div>
      </div>

    </div>

  </div>
  <!-- End #header-main-sticky-wrapper -->


</header>




<section id="hero">

  <div class="container">

    <div class="row">
      <div class="col-md-12">
        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
      </div>
    </div>

  </div>

</section>

<section>
  <div class="container">

    <div class="row">
      <div class="col-md-12">
        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure
          dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>



      </div>
    </div>

  </div>
</section>

只需将width:100%；添加到CSS中的.sticky-header类。