make accelerations magical again

frontend/src/app/components/acceleration/sparkles/acceleration-sparkles.component.html

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+<div class="sparkles" #sparkleAnchor>
+  <div *ngFor="let sparkle of sparkles" class="sparkle" [style]="sparkle.style">
+    <span class="inner-sparkle" [style]="sparkle.rotation">+</span>
+  </div>
+</div>

frontend/src/app/components/acceleration/sparkles/acceleration-sparkles.component.scss

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+.sparkles {
+  position: absolute;
+  top: var(--block-size);
+  height: 50px;
+  right: 0;
+}
+
+.sparkle {
+  position: absolute;
+  color: rgba(152, 88, 255, 0.75);
+  opacity: 0;
+  transform: scale(0.8) rotate(0deg);
+  animation: pop ease 2000ms forwards, sparkle ease 500ms infinite;
+}
+
+.inner-sparkle {
+  display: block;
+}
+
+@keyframes pop {
+  0% {
+    transform: scale(0.8) rotate(0deg);
+    opacity: 0;
+  }
+  20% {
+    transform: scale(1) rotate(72deg);
+    opacity: 1;
+  }
+  100% {
+    transform: scale(0) rotate(360deg);
+    opacity: 0;
+  }
+}
+
+@keyframes sparkle {
+  0% {
+    color: rgba(152, 88, 255, 0.75);
+  }
+  50% {
+    color: rgba(198, 162, 255, 0.75);
+  }
+  100% {
+    color: rgba(152, 88, 255, 0.75);
+  }
+}

frontend/src/app/components/acceleration/sparkles/acceleration-sparkles.component.ts

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+import { ChangeDetectionStrategy, ChangeDetectorRef, Component, ElementRef, Input, OnChanges, SimpleChanges, ViewChild } from '@angular/core';
+
+@Component({
+  selector: 'app-acceleration-sparkles',
+  templateUrl: './acceleration-sparkles.component.html',
+  styleUrls: ['./acceleration-sparkles.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class AccelerationSparklesComponent implements OnChanges {
+  @Input() arrow: ElementRef<HTMLDivElement>;
+  @Input() run: boolean = false;
+
+  @ViewChild('sparkleAnchor')
+  sparkleAnchor: ElementRef<HTMLDivElement>;
+
+  constructor(
+    private cd: ChangeDetectorRef,
+  ) {}
+
+  endTimeout: any;
+  lastSparkle: number = 0;
+  sparkleWidth: number = 0;
+  sparkles: any[] = [];
+
+  ngOnChanges(changes: SimpleChanges): void {
+    if (changes.run) {
+      if (this.endTimeout) {
+        clearTimeout(this.endTimeout);
+        this.endTimeout = null;
+      }
+      if (this.run) {
+        this.doSparkle();
+      } else {
+        this.endTimeout = setTimeout(() => {
+          this.sparkles = [];
+        }, 2000);
+      }
+    }
+  }
+
+  doSparkle(): void {
+    if (this.run) {
+      const now = performance.now();
+      if (now - this.lastSparkle > 30) {
+        this.lastSparkle = now;
+        if (this.arrow?.nativeElement && this.sparkleAnchor?.nativeElement) {
+          const anchor = this.sparkleAnchor.nativeElement.getBoundingClientRect().right;
+          const right = this.arrow.nativeElement.getBoundingClientRect().right;
+          const dx = (anchor - right) + 37.5;
+          this.sparkles.push({
+            style: {
+              right: dx + 'px',
+              top: (Math.random() * 30) + 'px',
+              animationDelay: (Math.random() * 50) + 'ms',
+            },
+            rotation: {
+              transform: `rotate(${Math.random() * 360}deg)`,
+            }
+          });
+          while (this.sparkles.length > 100) {
+            this.sparkles.shift();
+          }
+          this.cd.markForCheck();
+        }
+      }
+      requestAnimationFrame(() => {
+        this.doSparkle();
+      });
+    }
+  }
+}