@property --gradient-angle { syntax: "<angle>"; initial-value: 0deg; inherits: false; }
@property --gradient-angle-offset { syntax: "<angle>"; initial-value: 0deg; inherits: false; }
@property --gradient-percent { syntax: "<percentage>"; initial-value: 5%; inherits: false; }
@property --gradient-shine { syntax: "<color>"; initial-value: white; inherits: false; }

.shiny-cta, .shiny-cta-link {
    --shiny-cta-bg: #000000;
    --shiny-cta-bg-subtle: #1a1a1a;
    --shiny-cta-fg: #ffffff;
    --shiny-cta-highlight: #a78bfa;
    --shiny-cta-highlight-subtle: #7c3aed;
    --animation: gradient-angle linear infinite;
    --duration: 3s;
    --shadow-size: 2px;
    --transition: 800ms cubic-bezier(0.25, 1, 0.5, 1);
    isolation: isolate;
    position: relative;
    overflow: hidden;
    cursor: pointer;
    outline-offset: 4px;
    padding: 0.875rem 2rem;
    font-family: 'Inter', sans-serif;
    font-size: 1rem;
    line-height: 1.2;
    font-weight: 600;
    border: 1px solid transparent;
    border-radius: 0.75rem;
    color: var(--shiny-cta-fg);
    background: linear-gradient(var(--shiny-cta-bg), var(--shiny-cta-bg)) padding-box,
        conic-gradient(from calc(var(--gradient-angle) - var(--gradient-angle-offset)), transparent, var(--shiny-cta-highlight) var(--gradient-percent), var(--gradient-shine) calc(var(--gradient-percent) * 2), var(--shiny-cta-highlight) calc(var(--gradient-percent) * 3), transparent calc(var(--gradient-percent) * 4)) border-box;
    box-shadow: inset 0 0 0 1px var(--shiny-cta-bg-subtle);
    transition: var(--transition);
    transition-property: --gradient-angle-offset, --gradient-percent, --gradient-shine;
    text-decoration: none;
    display: inline-block;
}

.shiny-cta::before, .shiny-cta::after, .shiny-cta span::before,
.shiny-cta-link::before, .shiny-cta-link::after, .shiny-cta-link span::before {
    content: "";
    pointer-events: none;
    position: absolute;
    inset-inline-start: 50%;
    inset-block-start: 50%;
    translate: -50% -50%;
    z-index: -1;
}

.shiny-cta:active, .shiny-cta-link:active { translate: 0 1px; }

.shiny-cta::before, .shiny-cta-link::before {
    --size: calc(100% - var(--shadow-size) * 3);
    --position: 2px;
    --space: calc(var(--position) * 2);
    width: var(--size); height: var(--size);
    background: radial-gradient(circle at var(--position) var(--position), white calc(var(--position) / 4), transparent 0) padding-box;
    background-size: var(--space) var(--space);
    background-repeat: space;
    mask-image: conic-gradient(from calc(var(--gradient-angle) + 45deg), black, transparent 10% 90%, black);
    border-radius: 0.75rem;
    opacity: 0.4;
    z-index: -1;
}

.shiny-cta::after, .shiny-cta-link::after {
    --animation: shimmer linear infinite;
    width: 100%; aspect-ratio: 1;
    background: linear-gradient(-50deg, transparent, var(--shiny-cta-highlight), transparent);
    mask-image: radial-gradient(circle at bottom, transparent 40%, black);
    opacity: 0.6;
}

.shiny-cta span, .shiny-cta-link span { z-index: 1; }

.shiny-cta span::before, .shiny-cta-link span::before {
    --size: calc(100% + 1rem);
    width: var(--size); height: var(--size);
    box-shadow: inset 0 -1ex 2rem 4px var(--shiny-cta-highlight);
    opacity: 0;
    transition: opacity var(--transition);
    animation: calc(var(--duration) * 1.5) breathe linear infinite;
}

.shiny-cta, .shiny-cta::before, .shiny-cta::after,
.shiny-cta-link, .shiny-cta-link::before, .shiny-cta-link::after {
    animation: var(--animation) var(--duration), var(--animation) calc(var(--duration) / 0.4) reverse paused;
    animation-composition: add;
}

.shiny-cta:is(:hover, :focus-visible), .shiny-cta-link:is(:hover, :focus-visible) {
    --gradient-percent: 20%;
    --gradient-angle-offset: 95deg;
    --gradient-shine: var(--shiny-cta-highlight-subtle);
}

.shiny-cta:is(:hover, :focus-visible), .shiny-cta:is(:hover, :focus-visible)::before, .shiny-cta:is(:hover, :focus-visible)::after,
.shiny-cta-link:is(:hover, :focus-visible), .shiny-cta-link:is(:hover, :focus-visible)::before, .shiny-cta-link:is(:hover, :focus-visible)::after {
    animation-play-state: running;
}

.shiny-cta:is(:hover, :focus-visible) span::before, .shiny-cta-link:is(:hover, :focus-visible) span::before { opacity: 1; }

@keyframes gradient-angle { to { --gradient-angle: 360deg; } }
@keyframes shimmer { to { rotate: 360deg; } }
@keyframes breathe { from, to { scale: 1; } 50% { scale: 1.2; } }