fix(steps): vertical step has no separator line with no description

src/steps/demos/enUS/vertical.demo.md

@@ -11,6 +11,7 @@
       title="Let It Be"
       description="When I find myself in times of trouble Mother Mary comes to me"
     />
+    <n-step title="Break" />
     <n-step
       title="Come Together"
       description="Here come old flat top He come grooving up slowly"

src/steps/demos/zhCN/vertical.demo.md

@@ -11,6 +11,7 @@
       title="Let It Be"
       description="When I find myself in times of trouble Mother Mary comes to me"
     />
+    <n-step title="Break" />
     <n-step
       title="Come Together"
       description="Here come old flat top He come grooving up slowly"

src/steps/src/Step.tsx

@@ -107,8 +107,13 @@ export default defineComponent({
     }
   },
   render () {
+    const showDescription =
+      this.description !== undefined || this.$slots.default
     return (
-      <div class="n-step" style={this.cssVars as CSSProperties}>
+      <div
+        class={['n-step', { 'n-step--show-description': showDescription }]}
+        style={this.cssVars as CSSProperties}
+      >
         <div class="n-step-indicator">
           <div class="n-step-indicator-slot">
             <NIconSwitchTransition>
@@ -141,7 +146,7 @@ export default defineComponent({
             <div class="n-step-content-header__title">{this.title}</div>
             {!this.vertical ? <div class="n-step-splitor" /> : null}
           </div>
-          {this.description !== undefined || this.$slots.default ? (
+          {showDescription ? (
             <div class="n-step-content__description">
               {renderSlot(this.$slots, 'default', undefined, () => [
                 this.description

src/steps/src/styles/index.cssr.ts

@@ -1,4 +1,4 @@
-import { c, cB, cE, cM } from '../../../_utils/cssr'
+import { c, cB, cE, cM, cNotM } from '../../../_utils/cssr'
 import iconSwitchTransition from '../../../_styles/transitions/icon-switch'
 
 // vars:
@@ -117,6 +117,11 @@ export default cB('steps', `
   cM('vertical', {
     flexDirection: 'column'
   }, [
+    cNotM('show-description', [
+      cB('step', {
+        paddingBottom: '8px'
+      })
+    ]),
     cB('step', {
       marginBottom: '16px'
     }, [