我有一个无序的列表，我正用于菜单。每个项目都有一个背景图像和一个：悬停图像。第一个元素的背景图像与其余元素不同，因此我使用以下方法对其进行样式设置，其工作正常：
#prodNavBar ul:last-child li:first-child {...}
由于我也希望在此元素上使用翻转图像，因此我尝试添加:hover，如下所示：
#prodNavBar ul:last-child li:first-child:hover {...}
......但这不起作用。结合:first-child和:hover的语法是什么？
答案 0 :(得分：35)
在此处链接:first-child和:hover应该可以正常工作。但是，如果您使用的是IE6，则只能识别链中的最后一个伪类。
换句话说，你做得对。
答案 1 :(得分：12)
li:first-child:hover应该有效。您正在测试哪种浏览器？ IE不支持last-child
Here是一个示例测试用例。
答案 2 :(得分：1)
2020-10-03 00:37:44.898 6218-6218/? I/mple.myfirstap: Not late-enabling -Xcheck:jni (already on)
2020-10-03 00:37:44.914 6218-6218/? I/mple.myfirstap: Unquickening 12 vdex files!
2020-10-03 00:37:44.915 6218-6218/? W/mple.myfirstap: Unexpected CPU variant for X86 using defaults: x86
2020-10-03 00:37:45.070 6218-6218/com.example.myfirstapp D/NetworkSecurityConfig: Using Network Security Config from resource network_security_config debugBuild: true
2020-10-03 00:37:45.072 6218-6218/com.example.myfirstapp D/NetworkSecurityConfig: Using Network Security Config from resource network_security_config debugBuild: true
2020-10-03 00:37:45.082 6218-6243/com.example.myfirstapp D/libEGL: loaded /vendor/lib/egl/libEGL_emulation.so
2020-10-03 00:37:45.088 6218-6243/com.example.myfirstapp D/libEGL: loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
2020-10-03 00:37:45.092 6218-6243/com.example.myfirstapp D/libEGL: loaded /vendor/lib/egl/libGLESv2_emulation.so
2020-10-03 00:37:45.201 6218-6218/com.example.myfirstapp W/mple.myfirstap: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
2020-10-03 00:37:45.201 6218-6218/com.example.myfirstapp W/mple.myfirstap: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
2020-10-03 00:37:45.295 6218-6241/com.example.myfirstapp D/HostConnection: HostConnection::get() New Host Connection established 0xee254710, tid 6241
2020-10-03 00:37:45.299 6218-6241/com.example.myfirstapp D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_vulkan_free_memory_sync GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0
2020-10-03 00:37:45.301 6218-6241/com.example.myfirstapp W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
2020-10-03 00:37:45.306 6218-6241/com.example.myfirstapp D/EGL_emulation: eglCreateContext: 0xee064eb0: maj 3 min 0 rcv 3
2020-10-03 00:37:45.323 6218-6241/com.example.myfirstapp D/EGL_emulation: eglMakeCurrent: 0xee064eb0: ver 3 0 (tinfo 0xee3b5630) (first time)
2020-10-03 00:37:45.343 6218-6241/com.example.myfirstapp I/Gralloc4: mapper 4.x is not supported
2020-10-03 00:37:45.344 6218-6241/com.example.myfirstapp D/HostConnection: createUnique: call
2020-10-03 00:37:45.344 6218-6241/com.example.myfirstapp D/HostConnection: HostConnection::get() New Host Connection established 0xee253ed0, tid 6241
2020-10-03 00:37:45.369 6218-6241/com.example.myfirstapp D/goldfish-address-space: allocate: Ask for block of size 0x100
2020-10-03 00:37:45.369 6218-6241/com.example.myfirstapp D/goldfish-address-space: allocate: ioctl allocate returned offset 0x3fc7ba000 size 0x2000
2020-10-03 00:37:45.375 6218-6241/com.example.myfirstapp D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer ANDROID_EMU_vulkan_ignored_handles ANDROID_EMU_vulkan_free_memory_sync GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0
2020-10-03 00:37:47.795 6218-6218/com.example.myfirstapp W/mple.myfirstap: Accessing hidden method Landroid/graphics/FontFamily;-><init>()V (greylist-max-q, reflection, denied)
2020-10-03 00:37:47.797 6218-6218/com.example.myfirstapp E/TypefaceCompatApi26Impl: Unable to collect necessary methods for class java.lang.NoSuchMethodException
java.lang.NoSuchMethodException: android.graphics.FontFamily.<init> []
at java.lang.Class.getConstructor0(Class.java:2332)
at java.lang.Class.getConstructor(Class.java:1728)
at androidx.core.graphics.TypefaceCompatApi26Impl.obtainFontFamilyCtor(TypefaceCompatApi26Impl.java:321)
at androidx.core.graphics.TypefaceCompatApi26Impl.<init>(TypefaceCompatApi26Impl.java:84)
at androidx.core.graphics.TypefaceCompatApi28Impl.<init>(TypefaceCompatApi28Impl.java:36)
at androidx.core.graphics.TypefaceCompat.<clinit>(TypefaceCompat.java:47)
at androidx.core.graphics.TypefaceCompat.create(TypefaceCompat.java:190)
at androidx.appcompat.widget.AppCompatTextView.setTypeface(AppCompatTextView.java:705)
at android.widget.TextView.resolveStyleAndSetTypeface(TextView.java:2183)
at android.widget.TextView.setTypefaceFromAttrs(TextView.java:2154)
at android.widget.TextView.applyTextAppearance(TextView.java:4105)
at android.widget.TextView.<init>(TextView.java:1630)
at android.widget.TextView.<init>(TextView.java:990)
at androidx.appcompat.widget.AppCompatTextView.<init>(AppCompatTextView.java:99)
at androidx.appcompat.widget.AppCompatTextView.<init>(AppCompatTextView.java:95)
at androidx.appcompat.app.AppCompatViewInflater.createTextView(AppCompatViewInflater.java:182)
at androidx.appcompat.app.AppCompatViewInflater.createView(AppCompatViewInflater.java:103)
at androidx.appcompat.app.AppCompatDelegateImpl.createView(AppCompatDelegateImpl.java:1407)
at androidx.appcompat.app.AppCompatDelegateImpl.onCreateView(AppCompatDelegateImpl.java:1457)
at android.view.LayoutInflater.tryCreateView(LayoutInflater.java:1059)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:995)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:959)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1121)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1082)
at android.view.LayoutInflater.inflate(LayoutInflater.java:680)
at android.view.LayoutInflater.inflate(LayoutInflater.java:532)
at android.view.LayoutInflater.inflate(LayoutInflater.java:479)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161)
at com.example.myfirstapp.DisplayMessageActivity.onCreate(DisplayMessageActivity.java:163)
at android.app.Activity.performCreate(Activity.java:7995)
at android.app.Activity.performCreate(Activity.java:7979)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
2020-10-03 00:37:49.599 6218-6251/com.example.myfirstapp D/FragmentActivity: onFailure: caca