Hi,

Aren't those <br> tags breaking the layout of the navbar?

Can you try this code?

import React, { Component } from "react";
import {
MDBNavbar, MDBNavbarBrand, MDBNavbarNav, MDBNavItem, MDBNavLink, MDBNavbarToggler, MDBCollapse, MDBFormInline,
MDBDropdown, MDBDropdownToggle, MDBDropdownMenu, MDBDropdownItem
} from "mdbreact";

class NavbarPage extends Component {
state = {
  isOpen: false
};

toggleCollapse = () => {
  this.setState({ isOpen: !this.state.isOpen });
}

render() {
  return (
      <MDBNavbar color="primary-color" dark expand="md">
        <MDBNavbarBrand>
          <strong className="white-text">Navbar</strong>
        </MDBNavbarBrand>
        <MDBNavbarToggler onClick={this.toggleCollapse} />
        <MDBCollapse id="navbarCollapse3" isOpen={this.state.isOpen} navbar>
          <MDBNavbarNav left>
            <MDBNavItem active>
              <MDBNavLink to="#!">Home</MDBNavLink>
            </MDBNavItem>
            <MDBNavItem>
              <MDBNavLink to="#!">Features</MDBNavLink>
            </MDBNavItem>
            <MDBNavItem>
              <MDBNavLink to="#!">Pricing</MDBNavLink>
            </MDBNavItem>
            <MDBNavItem>
              <MDBDropdown>
                <MDBDropdownToggle nav caret>
                  <span className="mr-2">Dropdown</span>
                </MDBDropdownToggle>
                <MDBDropdownMenu color="primary">
                  <MDBDropdownItem href="#!">Action</MDBDropdownItem>
                  <MDBDropdownItem href="#!">Another Action</MDBDropdownItem>
                  <MDBDropdownItem href="#!">Something else here</MDBDropdownItem>
                  <MDBDropdownItem href="#!">Something else here</MDBDropdownItem>
                </MDBDropdownMenu>
              </MDBDropdown>
            </MDBNavItem>
          </MDBNavbarNav>
        </MDBCollapse>
      </MDBNavbar>
    );
  }
}

export default NavbarPage;

Maybe you've got custom styles which could collide with mdbs?

Best,

Jakub