diff --git a/lib/capybara/queries/selector_query.rb b/lib/capybara/queries/selector_query.rb
index f80d1a08..9596281d 100644
--- a/lib/capybara/queries/selector_query.rb
+++ b/lib/capybara/queries/selector_query.rb
@@ -61,6 +61,7 @@ module Capybara
         return true if (@resolved_node&.== node) && options[:allow_self]
 
         @applied_filters ||= :system
+        return false unless matches_id_filter?(node) && matches_class_filter?(node)
         return false unless matches_text_filter?(node) && matches_exact_text_filter?(node) && matches_visible_filter?(node)
 
         @applied_filters = :node
@@ -221,14 +222,7 @@ module Capybara
       end
 
       def filtered_xpath(expr)
-        if use_default_id_filter?
-          id_xpath = if options[:id].is_a? XPath::Expression
-            XPath.attr(:id)[options[:id]]
-          else
-            XPath.attr(:id) == options[:id]
-          end
-          expr = "(#{expr})[#{id_xpath}]"
-        end
+        expr = "(#{expr})[#{xpath_from_id}]" if use_default_id_filter?
         expr = "(#{expr})[#{xpath_from_classes}]" if use_default_class_filter?
         expr
       end
@@ -250,33 +244,58 @@ module Capybara
       end
 
       def css_from_classes
-        if options[:class].is_a?(XPath::Expression)
+        case options[:class]
+        when XPath::Expression
           raise ArgumentError, 'XPath expressions are not supported for the :class filter with CSS based selectors'
+        when Regexp
+          strs = Selector::RegexpDisassembler.new(options[:class]).substrings
+          strs.map { |str| "[class*='#{str}'#{' i' if options[:class].casefold?}]" }.join
+        else
+          classes = Array(options[:class]).group_by { |cl| cl.start_with? '!' }
+          (classes[false].to_a.map { |cl| ".#{Capybara::Selector::CSS.escape(cl)}" } +
+          classes[true].to_a.map { |cl| ":not(.#{Capybara::Selector::CSS.escape(cl.slice(1..-1))})" }).join
         end
-
-        classes = Array(options[:class]).group_by { |cl| cl.start_with? '!' }
-        (classes[false].to_a.map { |cl| ".#{Capybara::Selector::CSS.escape(cl)}" } +
-         classes[true].to_a.map { |cl| ":not(.#{Capybara::Selector::CSS.escape(cl.slice(1..-1))})" }).join
       end
 
       def css_from_id
-        if options[:id].is_a?(XPath::Expression)
+        case options[:id]
+        when XPath::Expression
           raise ArgumentError, 'XPath expressions are not supported for the :id filter with CSS based selectors'
+        when Regexp
+          Selector::RegexpDisassembler.new(options[:id]).substrings.map do |str|
+            "[id*='#{str}'#{' i' if options[:id].casefold?}]"
+          end.join
+        else
+          "##{::Capybara::Selector::CSS.escape(options[:id])}"
         end
+      end
 
-        "##{::Capybara::Selector::CSS.escape(options[:id])}"
+      def xpath_from_id
+        case options[:id]
+        when XPath::Expression
+          XPath.attr(:id)[options[:id]]
+        when Regexp
+          XPath.attr(:id)[regexp_to_xpath_conditions(options[:id])]
+        else
+          XPath.attr(:id) == options[:id]
+        end
       end
 
       def xpath_from_classes
-        return XPath.attr(:class)[options[:class]] if options[:class].is_a?(XPath::Expression)
-
-        Array(options[:class]).map do |klass|
-          if klass.start_with?('!')
-            !XPath.attr(:class).contains_word(klass.slice(1..-1))
-          else
-            XPath.attr(:class).contains_word(klass)
-          end
-        end.reduce(:&)
+        case options[:class]
+        when XPath::Expression
+          XPath.attr(:class)[options[:class]]
+        when Regexp
+          XPath.attr(:class)[regexp_to_xpath_conditions(options[:class])]
+        else
+          Array(options[:class]).map do |klass|
+            if klass.start_with?('!')
+              !XPath.attr(:class).contains_word(klass.slice(1..-1))
+            else
+              XPath.attr(:class).contains_word(klass)
+            end
+          end.reduce(:&)
+        end
       end
 
       def apply_expression_filters(expression)
@@ -320,6 +339,18 @@ module Capybara
         node.is_a?(::Capybara::Node::Simple) && node.path == '/'
       end
 
+      def matches_id_filter?(node)
+        return true unless use_default_id_filter? && options[:id].is_a?(Regexp)
+
+        node[:id] =~ options[:id]
+      end
+
+      def matches_class_filter?(node)
+        return true unless use_default_class_filter? && options[:class].is_a?(Regexp)
+
+        node[:class] =~ options[:class]
+      end
+
       def matches_text_filter?(node)
         value = options[:text]
         return true unless value
@@ -357,6 +388,14 @@ module Capybara
         text_visible = :all if text_visible == :hidden
         !!node.text(text_visible, normalize_ws: normalize_ws).match(regexp)
       end
+
+      def regexp_to_xpath_conditions(regexp)
+        condition = XPath.current
+        condition = condition.uppercase if regexp.casefold?
+        Selector::RegexpDisassembler.new(regexp).substrings.map do |str|
+          condition.contains(str)
+        end.reduce(:&)
+      end
     end
   end
 end
diff --git a/lib/capybara/rack_test/driver.rb b/lib/capybara/rack_test/driver.rb
index 68c535a9..f7ca1ad0 100644
--- a/lib/capybara/rack_test/driver.rb
+++ b/lib/capybara/rack_test/driver.rb
@@ -75,6 +75,10 @@ class Capybara::RackTest::Driver < Capybara::Driver::Base
 
   def find_css(selector)
     browser.find(:css, selector)
+  rescue Nokogiri::CSS::SyntaxError
+    raise unless selector.include?(' i]')
+
+    raise ArgumentError, "This driver doesn't support case insensitive attribute matching when using CSS base selectors"
   end
 
   def html
diff --git a/lib/capybara/selector.rb b/lib/capybara/selector.rb
index 4df2be83..67d988b5 100644
--- a/lib/capybara/selector.rb
+++ b/lib/capybara/selector.rb
@@ -97,7 +97,7 @@ Capybara.add_selector(:link) do
               when true
                 XPath.attr(:href)
               when Regexp
-                XPath.attr(:href)[regexp_to_conditions(href)]
+                XPath.attr(:href)[regexp_to_xpath_conditions(href)]
               else
                 XPath.attr(:href) == href.to_s
               end
@@ -138,7 +138,7 @@ Capybara.add_selector(:link) do
     if (href = options[:href])
       if !href.is_a?(Regexp)
         desc << " with href #{href.inspect}"
-      elsif regexp_to_conditions(href)
+      elsif regexp_to_xpath_conditions(href)
         desc << " with href matching #{href.inspect}"
       end
     end
@@ -147,7 +147,7 @@ Capybara.add_selector(:link) do
   end
 
   describe_node_filters do |href: nil, **|
-    " with href matching #{href.inspect}" if href.is_a?(Regexp) && regexp_to_conditions(href).nil?
+    " with href matching #{href.inspect}" if href.is_a?(Regexp) && regexp_to_xpath_conditions(href).nil?
   end
 end
 
@@ -483,7 +483,7 @@ Capybara.add_selector(:element) do
   expression_filter(:attributes, matcher: /.+/) do |xpath, name, val|
     case val
     when Regexp
-      xpath[XPath.attr(name)[regexp_to_conditions(val)]]
+      xpath[XPath.attr(name)[regexp_to_xpath_conditions(val)]]
     when true
       xpath[XPath.attr(name)]
     when false
diff --git a/lib/capybara/selector/regexp_disassembler.rb b/lib/capybara/selector/regexp_disassembler.rb
index 914ceb5c..fee6f6df 100644
--- a/lib/capybara/selector/regexp_disassembler.rb
+++ b/lib/capybara/selector/regexp_disassembler.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'xpath'
-
 module Capybara
   class Selector
     class RegexpDisassembler
@@ -10,14 +8,6 @@ module Capybara
         @regexp_source = regexp.source
       end
 
-      def conditions
-        condition = XPath.current
-        condition = condition.uppercase if @regexp.casefold?
-        substrings.map do |str|
-          condition.contains(@regexp.casefold? ? str.upcase : str)
-        end.reduce(:&)
-      end
-
       def substrings
         @substrings ||= begin
           source = @regexp_source.dup
@@ -37,7 +27,9 @@ module Capybara
           end
           return [] if source.include?('|') # can't handle alternation here
 
-          source.match(/\A\^?(.*?)\$?\Z/).captures[0].split('.').reject(&:empty?).uniq
+          strs = source.match(/\A\^?(.*?)\$?\Z/).captures[0].split('.').reject(&:empty?).uniq
+          strs = strs.map(&:upcase) if @regexp.casefold?
+          strs
         end
       end
 
diff --git a/lib/capybara/selector/selector.rb b/lib/capybara/selector/selector.rb
index 438dc426..3e187d49 100644
--- a/lib/capybara/selector/selector.rb
+++ b/lib/capybara/selector/selector.rb
@@ -446,8 +446,12 @@ module Capybara
       Array(classes).map { |klass| XPath.attr(:class).contains_word(klass) }.reduce(:&)
     end
 
-    def regexp_to_conditions(regexp)
-      RegexpDisassembler.new(regexp).conditions
+    def regexp_to_xpath_conditions(regexp)
+      condition = XPath.current
+      condition = condition.uppercase if regexp.casefold?
+      RegexpDisassembler.new(regexp).substrings.map do |str|
+        condition.contains(str)
+      end.reduce(:&)
     end
   end
 end
diff --git a/lib/capybara/spec/session/has_css_spec.rb b/lib/capybara/spec/session/has_css_spec.rb
index 40730841..b89c52c5 100644
--- a/lib/capybara/spec/session/has_css_spec.rb
+++ b/lib/capybara/spec/session/has_css_spec.rb
@@ -23,6 +23,22 @@ Capybara::SpecHelper.spec '#has_css?' do
     expect(@session).not_to have_css('p.nosuchclass')
   end
 
+  it 'should support :id option' do
+    expect(@session).to have_css('h2', id: 'h2one')
+    expect(@session).to have_css('h2')
+    expect(@session).to have_css('h2', id: /h2o/)
+  end
+
+  it 'should support :class option' do
+    expect(@session).to have_css('li', class: 'guitarist')
+    expect(@session).to have_css('li', class: /guitar/)
+  end
+
+  it 'should support case insensitive :class and :id options' do
+    expect(@session).to have_css('li', class: /UiTaRI/i)
+    expect(@session).to have_css('h2', id: /2ON/i)
+  end
+
   it 'should respect scopes' do
     @session.within "//p[@id='first']" do
       expect(@session).to have_css('a#foo')
diff --git a/lib/capybara/spec/session/selectors_spec.rb b/lib/capybara/spec/session/selectors_spec.rb
index 359b34e5..88328abc 100644
--- a/lib/capybara/spec/session/selectors_spec.rb
+++ b/lib/capybara/spec/session/selectors_spec.rb
@@ -40,8 +40,18 @@ Capybara::SpecHelper.spec Capybara::Selector do
   end
 
   describe 'field selectors' do
-    it 'can find specifically by id' do
-      expect(@session.find(:field, id: 'customer_email').value).to eq 'ben@ben.com'
+    context 'with :id option' do
+      it 'can find specifically by id' do
+        expect(@session.find(:field, id: 'customer_email').value).to eq 'ben@ben.com'
+      end
+
+      it 'can find by regex' do
+        expect(@session.find(:field, id: /ustomer.emai/).value).to eq 'ben@ben.com'
+      end
+
+      it 'can find by case-insensitive id' do
+        expect(@session.find(:field, id: /StOmer.emAI/i).value).to eq 'ben@ben.com'
+      end
     end
 
     it 'can find specifically by name' do
diff --git a/lib/capybara/spec/views/form.erb b/lib/capybara/spec/views/form.erb
index afac5035..378d3179 100644
--- a/lib/capybara/spec/views/form.erb
+++ b/lib/capybara/spec/views/form.erb
@@ -25,6 +25,12 @@
     </label>
   </p>
 
+  <p>
+    <label for="customer_other_email">Customer Other Email
+      <input type="text" name="form[customer_other_email]" value="notben@notben.com" id="customer_other_email"/>
+    </label>
+  </p>
+
   <p>
     <label for="form_other_title">Other title</label>
     <select name="form[other_title]" id="form_other_title">
diff --git a/spec/dsl_spec.rb b/spec/dsl_spec.rb
index 5674d3ab..ee7cf89e 100644
--- a/spec/dsl_spec.rb
+++ b/spec/dsl_spec.rb
@@ -9,7 +9,12 @@ end
 
 Capybara::SpecHelper.run_specs TestClass.new, 'DSL', capybara_skip: %i[
   js modals screenshot frames windows send_keys server hover about_scheme psc download css driver
-]
+] do |example|
+  case example.metadata[:full_description]
+  when /has_css\? should support case insensitive :class and :id options/
+    pending "Nokogiri doesn't support case insensitive CSS attribute matchers"
+  end
+end
 
 RSpec.describe Capybara::DSL do
   after do
diff --git a/spec/rack_test_spec.rb b/spec/rack_test_spec.rb
index fc2146a1..4cad25f0 100644
--- a/spec/rack_test_spec.rb
+++ b/spec/rack_test_spec.rb
@@ -19,7 +19,12 @@ skipped_tests = %i[
   download
   css
 ]
-Capybara::SpecHelper.run_specs TestSessions::RackTest, 'RackTest', capybara_skip: skipped_tests
+Capybara::SpecHelper.run_specs TestSessions::RackTest, 'RackTest', capybara_skip: skipped_tests do |example|
+  case example.metadata[:full_description]
+  when /has_css\? should support case insensitive :class and :id options/
+    pending "Nokogiri doesn't support case insensitive CSS attribute matchers"
+  end
+end
 
 RSpec.describe Capybara::Session do # rubocop:disable RSpec/MultipleDescribes
   context 'with rack test driver' do
diff --git a/spec/selector_spec.rb b/spec/selector_spec.rb
index 26c51d7e..5d26ad70 100644
--- a/spec/selector_spec.rb
+++ b/spec/selector_spec.rb
@@ -148,6 +148,15 @@ RSpec.describe Capybara do
           expect { string.find(:custom_css_selector, 'div', id: XPath.contains('peci')) }
             .to raise_error(ArgumentError, /not supported/)
         end
+
+        it 'accepts Regexp for xpath based selectors' do
+          expect(string.find(:custom_xpath_selector, './/div', id: /peci/)[:id]).to eq '#special'
+          expect(string.find(:custom_xpath_selector, './/div', id: /pEcI/i)[:id]).to eq '#special'
+        end
+
+        it 'accepts Regexp for css based selectors' do
+          expect(string.find(:custom_css_selector, 'div', id: /sp.*al/)[:id]).to eq '#special'
+        end
       end
 
       context 'with :class option' do
@@ -177,6 +186,15 @@ RSpec.describe Capybara do
           expect { string.find(:custom_css_selector, 'div', class: XPath.contains('random')) }
             .to raise_error(ArgumentError, /not supported/)
         end
+
+        it 'accepts Regexp for XPath based selectors' do
+          expect(string.find(:custom_xpath_selector, './/div', class: /dom wor/)[:id]).to eq 'random_words'
+          expect(string.find(:custom_xpath_selector, './/div', class: /dOm WoR/i)[:id]).to eq 'random_words'
+        end
+
+        it 'accepts Regexp for CSS base selectors' do
+          expect(string.find(:custom_css_selector, 'div', class: /random/)[:id]).to eq 'random_words'
+        end
       end
 
       # :css, :xpath, :id, :field, :fieldset, :link, :button, :link_or_button, :fillable_field, :radio_button, :checkbox, :select,
@@ -207,10 +225,14 @@ RSpec.describe Capybara do
           expect(string.find(:field, 'form[my_text_input]')[:id]).to eq 'my_text_input'
         end
 
-        it 'finds by id' do
+        it 'finds by id string' do
           expect(string.find(:field, id: 'my_text_input')[:name]).to eq 'form[my_text_input]'
         end
 
+        it 'finds by id regexp' do
+          expect(string.find(:field, id: /my_text_inp/)[:name]).to eq 'form[my_text_input]'
+        end
+
         it 'finds by name' do
           expect(string.find(:field, name: 'form[my_text_input]')[:id]).to eq 'my_text_input'
         end