Вопрос
Мне бы хотелось, чтобы красная часть двигалась вдоль пути до конца (так от верхней правой стороны до левой нижней стороны):
Подумайте об использовании анимации заполнения линии с штрих-смещением.
Для ясности я поместил точно такую же кривую ниже, которая будет показывать маршрут заполнения линии цветом
Если это указание траектории движения не является необходимым, просто удалить path
id = "trace"
<svg id="fil" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 783.53 362">
<defs>
<style>
.cls-3{
fill: none;
stroke-miterlimit:10;
stroke-width:3px;
stroke:#E7E7E7;
}
#base {
fill: none;
stroke:crimson;
stroke-width:3px;
stroke-dashoffset:1732;
stroke-dasharray:1732;
animation: fillStroke 10s linear forwards;
}
@keyframes fillStroke {
to {stroke-dashoffset:0;}
}
</style>
</defs>
<g transform="translate(-352.32 -8.93)">
<path id="trace" class="cls-3" d="M656.89,8.93c0,48,7.42,124.9,64.45,125.92a115.56,115.56,0,0,0,53.83-12.28c8.35-4.2,16.35-9.59,21.84-17.15s8.15-17.62,5.25-26.51c-3.12-9.53-12.16-16.28-21.87-18.83-61.57-16.19-142.83,57.7-139.63,119.4,1.23,23.69,16.72,41.59,37.61,51.29,27,12.55,60.55,13.36,89.45,8.06,12.25-2.25,25.82-5.25,37.26-10.44,12.63-5.72,32.28-20.08,28.88-36.64a18,18,0,0,0-15.63-14.59c-10.28-1.4-19.14,3.57-26.76,10-16.18,13.66-29.34,30.65-44.7,45.2a359.34,359.34,0,0,1-49.33,39.08A356.65,356.65,0,0,1,638.08,303c-35.77,14.83-90.88,29.56-123.22-.47-11.61-10.78-17.61-26.71-18.41-42.53-1.07-21.19,4.41-54.95,30-59.28,36.67-6.2,78.65,49.05,86.38,79.36,8.2,32.14-5.44,70.78-35.75,84.26-28.8,12.81-63.93,0-85.8-22.72-23.52-24.41-18.59-55.9-36.07-82.56-16-24.39-41.3-23.5-66.77-24.62" />
<g class="cls-2">
<path id="base" d="M656.89,8.93c0,48,7.42,124.9,64.45,125.92a115.56,115.56,0,0,0,53.83-12.28c8.35-4.2,16.35-9.59,21.84-17.15s8.15-17.62,5.25-26.51c-3.12-9.53-12.16-16.28-21.87-18.83-61.57-16.19-142.83,57.7-139.63,119.4,1.23,23.69,16.72,41.59,37.61,51.29,27,12.55,60.55,13.36,89.45,8.06,12.25-2.25,25.82-5.25,37.26-10.44,12.63-5.72,32.28-20.08,28.88-36.64a18,18,0,0,0-15.63-14.59c-10.28-1.4-19.14,3.57-26.76,10-16.18,13.66-29.34,30.65-44.7,45.2a359.34,359.34,0,0,1-49.33,39.08A356.65,356.65,0,0,1,638.08,303c-35.77,14.83-90.88,29.56-123.22-.47-11.61-10.78-17.61-26.71-18.41-42.53-1.07-21.19,4.41-54.95,30-59.28,36.67-6.2,78.65,49.05,86.38,79.36,8.2,32.14-5.44,70.78-35.75,84.26-28.8,12.81-63.93,0-85.8-22.72-23.52-24.41-18.59-55.9-36.07-82.56-16-24.39-41.3-23.5-66.77-24.62" >
</path>
</g>
</g>
</svg>
Опция анимации градиента
Вместо заполнения цветом при увеличении длины кривой, градиент будет выполнять эту функцию
<svg id="fil" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 783.53 362">
<defs>
<style>
.cls-3{
fill: none;
stroke-miterlimit:10;
stroke-width:3px;
stroke:#E7E7E7;
}
#base {
fill: none;
stroke:url(#light);
stroke-width:3px;
stroke-dashoffset:1732;
stroke-dasharray:1732;
animation: fillStroke 10s linear forwards;
}
@keyframes fillStroke {
to {stroke-dashoffset:0;}
}
</style>
<linearGradient id="light" x1="100%" y1="100%">
<stop offset="50%" stop-color="#CF4B59">
<!-- <animate attributeName="stop-color" from="#CF4B59" to="#3E3E3E" dur="10s" fill="freeze" /> -->
</stop>
<stop offset="100%" stop-color="#3E3E3E">
<!-- <animate attributeName="stop-color" to="#CF4B59" from="#3E3E3E" dur="10s" fill="freeze" /> -->
</stop>
</linearGradient>
</defs>
<g transform="translate(-352.32 -8.93)">
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<g class="cls-2">
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</path>
</g>
</g>
</svg>