Ruby on rails rails、引导、仅媒体断点

我在网上花了一天的时间试图让bootstrap的媒体断点只起作用，而没有找到明确的指示

我的引导导航栏工作正常，因此，我怀疑，我的引导安装正确

我想让以下代码正常工作：

h1 {
 @include media-breakpoint-only(xs) {
   color: red;
 }
 @include media-breakpoint-only(sm) {
   color: green;
 }
 @include media-breakpoint-only(md) {
   color: blue;
 }
 @include media-breakpoint-only(lg) {
   color: yellow;
 }
 @include media-breakpoint-only(xl) {
   color: orange;
 }
}

但我不知道该把这段代码放在哪里，也不知道需要做什么额外的事情才能让媒体断点只工作

当我将上述代码放在application.scss（见下文）的末尾时，我得到以下错误：

“仅媒体断点”中未定义的混合

我的档案是

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

ruby '2.5.1'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 5.2.0'
# Use postgresql as the database for Active Record
gem 'pg', '>= 0.18', '< 2.0'
# Use Puma as the app server
gem 'puma', '~> 3.11'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'mini_racer', platforms: :ruby

# Shnelvar
gem 'jquery-rails' 

# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.2'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.5'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use ActiveStorage variant
# gem 'mini_magick', '~> 4.8'

# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.1.0', require: false

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end

group :development do
  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '>= 3.0.5', '< 3.2'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'
end

group :test do
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '>= 2.15', '< 4.0'
  gem 'selenium-webdriver'
  # Easy installation and use of chromedriver to run system tests with Chrome
  gem 'chromedriver-helper'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

gem 'bootstrap-sass', '~> 3.3', '>= 3.3.7'
gem 'bootstrap', '~> 4.1.3'

application.scss

/*
 * This is a manifest file that'll be compiled into application.css, which will include all the files
 * listed below.
 *
 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
 * vendor/assets/stylesheets directory can be referenced here using a relative path.
 *
 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
 * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
 * files in this directory. Styles in this file should be added after the last require_* statement.
 * It is generally better to create a new file per style scope.
 *
 * require_tree .
 * require_self
 */

// See 
//  https://www.youtube.com/watch?v=vcBXXOdPfgE&index=8&list=PLYM1n9xxMy4ClO2GjX73U3BLsXx9Z7wh5
$navbar-default-bg: red;

// Shnelvar
//   See https://github.com/twbs/bootstrap-sass
@import "bootstrap-sprockets";

// Custom bootstrap variables must be set or imported *before* bootstrap.
@import "bootstrap";

// Shnelvar
//   For ralph-shiny-button etc.
@import "ralph";

// Shnelvar
//   See https://stackoverflow.com/questions/33404154/bootstrap-change-the-navbar-font-size
//   See https://teamtreehouse.com/community/how-do-you-change-the-bootstrap-font-style
.nav a{
    color: white !important;
    // font-size: 3.8em !important;
    font-size: 2.8em;
    }

---

这很可能是因为您在自己的样式表之后导入引导样式表。请参阅，

*require_tree.

中的

应用程序.css

文件意味着您从

app/assets/stylesheets

导入了所有样式表，因此您会收到一个错误，因为当时引导程序的混音还不可用

例如，为了解决这个问题，我建议创建一个全局样式表文件

app/assets/stylesheets/main.scss

，在这里您可以按正确的顺序导入所有内容

// app/assets/stylesheets/main.scss
$navbar-default-bg: red;

@import "bootstrap-sprockets"
@import "bootstrap"

@import "some-file"   // import specific file from app/assets/stylesheets/
@import "some-dir/*"  // import whole directory from app/assets/stylesheets/

// any other styles here

而在

application.css中

仅保留：

/*
 * This is a manifest file that'll be compiled into application.css, which will include all the files
 * listed below.
 *
 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
 * vendor/assets/stylesheets directory can be referenced here using a relative path.
 *
 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
 * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
 * files in this directory. Styles in this file should be added after the last require_* statement.
 * It is generally better to create a new file per style scope.
 *
 * require main
 * require_self
 */

---

但是

requiremain

和

requireself

被注释掉了！Rails使用解析这些注释的方法。我是否遗漏了什么？我没有

*=requiremain

。我有

*需要main

请参阅以获取解决方案。

/*
 * This is a manifest file that'll be compiled into application.css, which will include all the files
 * listed below.
 *
 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
 * vendor/assets/stylesheets directory can be referenced here using a relative path.
 *
 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
 * compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
 * files in this directory. Styles in this file should be added after the last require_* statement.
 * It is generally better to create a new file per style scope.
 *
 * require main
 * require_self
 */