[Bug]: Incorrect parsing @keyframes rule

[Sepush]

Incorrect deal with @Keyframes rule for animation relted css

export default c([
  c('@keyframes heatmap-loading', `
    0% {
      background: var(--n-loading-color-start);
    }
    40% {
      background: var(--n-loading-color-end);
    }
    80% {
      background: var(--n-loading-color-start);
    }
    100% {
      background: var(--n-loading-color-start);
    }
  `),
]);