1 00:00:01,140 --> 00:00:04,380 ‫One important part of building web applications 2 00:00:04,380 --> 00:00:07,950 ‫is, of course, to style them with CSS. 3 00:00:07,950 --> 00:00:10,710 ‫Now, up until this point, we have always just 4 00:00:10,710 --> 00:00:15,540 ‫included a global external CSS file into our applications, 5 00:00:15,540 --> 00:00:20,220 ‫and then used the class names from there in our JSX. 6 00:00:20,220 --> 00:00:22,170 ‫However, in this project, 7 00:00:22,170 --> 00:00:24,390 ‫we will do something a bit different, 8 00:00:24,390 --> 00:00:27,450 ‫which is to use CSS modules. 9 00:00:27,450 --> 00:00:30,000 ‫But before we do that, I want to take a minute 10 00:00:30,000 --> 00:00:32,670 ‫to quickly explore all the different options 11 00:00:32,670 --> 00:00:35,700 ‫that we can use to style React applications 12 00:00:35,700 --> 00:00:38,733 ‫because there are actually a lot of them. 13 00:00:40,350 --> 00:00:43,380 ‫But first you might be wondering, why are there 14 00:00:43,380 --> 00:00:48,180 ‫actually so many different ways of styling a React app? 15 00:00:48,180 --> 00:00:52,110 ‫Well, it's because one fundamental philosophy of React 16 00:00:52,110 --> 00:00:55,020 ‫is to be unopinionated in regards 17 00:00:55,020 --> 00:00:59,070 ‫to many common aspects of building web applications. 18 00:00:59,070 --> 00:01:02,190 ‫And so one of them is styling. 19 00:01:02,190 --> 00:01:04,260 ‫So React really doesn't care 20 00:01:04,260 --> 00:01:06,990 ‫about how you style your applications. 21 00:01:06,990 --> 00:01:08,550 ‫And so as a result, 22 00:01:08,550 --> 00:01:11,160 ‫we have lots of different styling options, 23 00:01:11,160 --> 00:01:15,390 ‫most of them being provided by third party libraries. 24 00:01:15,390 --> 00:01:17,730 ‫So the first option is one 25 00:01:17,730 --> 00:01:20,250 ‫that we have used a few times in the beginning, 26 00:01:20,250 --> 00:01:23,220 ‫which is to simply apply some inline CSS 27 00:01:23,220 --> 00:01:27,367 ‫to JSX elements using this style prop. 28 00:01:27,367 --> 00:01:29,310 ‫Now, this is actually more common in React 29 00:01:29,310 --> 00:01:31,200 ‫than in regular HTML 30 00:01:31,200 --> 00:01:35,433 ‫because of React's idea of separation of concerns. 31 00:01:36,390 --> 00:01:38,940 ‫Now, an inline style is scoped 32 00:01:38,940 --> 00:01:42,750 ‫to the particular JSX element that it's applied to, 33 00:01:42,750 --> 00:01:45,660 ‫which means that it is locally scoped, 34 00:01:45,660 --> 00:01:49,860 ‫so it applies only to that exact element. 35 00:01:49,860 --> 00:01:52,230 ‫Now, we have also multiple times 36 00:01:52,230 --> 00:01:54,900 ‫included an external CSS file, 37 00:01:54,900 --> 00:01:57,720 ‫and then simply applied the CSS classes 38 00:01:57,720 --> 00:02:00,180 ‫using the class name prop. 39 00:02:00,180 --> 00:02:01,830 ‫And the same would actually 40 00:02:01,830 --> 00:02:05,130 ‫also have worked for a Sass file. 41 00:02:05,130 --> 00:02:08,880 ‫Now, in this case, our styles are actually global, 42 00:02:08,880 --> 00:02:11,880 ‫which means that every single JSX element 43 00:02:11,880 --> 00:02:15,870 ‫in the entire application could use any of these classes 44 00:02:15,870 --> 00:02:18,510 ‫in the external CSS file. 45 00:02:18,510 --> 00:02:20,820 ‫And this can create huge problems, 46 00:02:20,820 --> 00:02:23,250 ‫especially in big projects, 47 00:02:23,250 --> 00:02:25,350 ‫for example, because you won't know 48 00:02:25,350 --> 00:02:28,470 ‫which components are using which classes. 49 00:02:28,470 --> 00:02:30,990 ‫And when you then update one of the classes, 50 00:02:30,990 --> 00:02:34,530 ‫it will have repercussions in other components, 51 00:02:34,530 --> 00:02:37,050 ‫or when a developer adds a new class 52 00:02:37,050 --> 00:02:39,210 ‫with a name that already exists, 53 00:02:39,210 --> 00:02:43,350 ‫that will create clashes between those two classes. 54 00:02:43,350 --> 00:02:48,350 ‫So basically, global CSS is a nightmare in large apps. 55 00:02:48,570 --> 00:02:53,570 ‫So in professional projects, CSS is almost never global. 56 00:02:53,970 --> 00:02:58,560 ‫Instead, CSS should be scoped to an individual component, 57 00:02:58,560 --> 00:03:01,380 ‫which brings us to the next styling options, 58 00:03:01,380 --> 00:03:03,843 ‫which is CSS modules. 59 00:03:04,680 --> 00:03:09,090 ‫CSS modules are pretty similar to regular CSS files 60 00:03:09,090 --> 00:03:12,450 ‫with the difference that we write just one CSS file 61 00:03:12,450 --> 00:03:15,180 ‫for each of our components. 62 00:03:15,180 --> 00:03:17,880 ‫The styles in that file will then be scoped 63 00:03:17,880 --> 00:03:19,830 ‫to only that component 64 00:03:19,830 --> 00:03:22,830 ‫so that no other component can use them. 65 00:03:22,830 --> 00:03:24,660 ‫And this then makes the components 66 00:03:24,660 --> 00:03:27,240 ‫way more modular and reusable. 67 00:03:27,240 --> 00:03:28,650 ‫And at the same time, 68 00:03:28,650 --> 00:03:32,670 ‫it better reflects React's separation of concerns. 69 00:03:32,670 --> 00:03:34,020 ‫And in fact, 70 00:03:34,020 --> 00:03:38,310 ‫this is exactly what we will do in this project. 71 00:03:38,310 --> 00:03:41,190 ‫Now, if you want to take it even one step further, 72 00:03:41,190 --> 00:03:44,550 ‫you can go with a CSS in JavaScript library 73 00:03:44,550 --> 00:03:46,083 ‫like styled components. 74 00:03:46,920 --> 00:03:50,700 ‫So as the name says with CSS in JavaScript, 75 00:03:50,700 --> 00:03:55,590 ‫you actually write your CSS inside a JavaScript file, 76 00:03:55,590 --> 00:03:59,103 ‫so in the same file where you define your components. 77 00:03:59,970 --> 00:04:03,480 ‫What's special about a CSS in JavaScript library 78 00:04:03,480 --> 00:04:06,480 ‫is that it allows us to create React components 79 00:04:06,480 --> 00:04:09,510 ‫that have our styles directly apply to them, 80 00:04:09,510 --> 00:04:13,170 ‫which we can then use just like regular components. 81 00:04:13,170 --> 00:04:16,020 ‫So this fully embraces the React philosophy 82 00:04:16,020 --> 00:04:19,080 ‫that a component should contain all the information 83 00:04:19,080 --> 00:04:22,713 ‫about its appearance, and so that includes CSS. 84 00:04:23,640 --> 00:04:28,470 ‫And finally, you can also use a utility-first CSS framework 85 00:04:28,470 --> 00:04:33,470 ‫like Tailwind, which is getting more popular every day. 86 00:04:33,480 --> 00:04:37,260 ‫So in Tailwind, you use predefined utility classes 87 00:04:37,260 --> 00:04:40,620 ‫to define individual styles, to use flexbox, 88 00:04:40,620 --> 00:04:44,130 ‫to make layouts responsive, to make hover effects, 89 00:04:44,130 --> 00:04:47,190 ‫and really to design your entire UI, 90 00:04:47,190 --> 00:04:51,513 ‫and all that without ever having to leave the JSX markup. 91 00:04:52,740 --> 00:04:54,720 ‫Okay, now finally, 92 00:04:54,720 --> 00:04:57,930 ‫you do actually have one more option here, 93 00:04:57,930 --> 00:05:02,550 ‫which is basically to not write any CSS at all. 94 00:05:02,550 --> 00:05:05,580 ‫Wait, what? No CSS? 95 00:05:05,580 --> 00:05:07,680 ‫Well, it is actually possible, 96 00:05:07,680 --> 00:05:10,200 ‫because you can build your entire project 97 00:05:10,200 --> 00:05:13,860 ‫using a fully fledged UI component library, 98 00:05:13,860 --> 00:05:18,860 ‫for example, like Material UI, Chakra UI, or Mantine. 99 00:05:18,900 --> 00:05:22,050 ‫So essentially, a component library like those 100 00:05:22,050 --> 00:05:26,790 ‫contains all kinds of prebuilt and pre-styled components 101 00:05:26,790 --> 00:05:30,210 ‫that are common in most web applications. 102 00:05:30,210 --> 00:05:33,300 ‫This is, however, not ideal for beginners, 103 00:05:33,300 --> 00:05:36,630 ‫but again, it might be worth exploring later. 104 00:05:36,630 --> 00:05:38,010 ‫And there you have it. 105 00:05:38,010 --> 00:05:39,900 ‫So these are the different ways 106 00:05:39,900 --> 00:05:42,990 ‫in which we can style React applications. 107 00:05:42,990 --> 00:05:46,773 ‫And so in this project, we will now explore CSS modules.