/*
 * transitions.css — SPA-light page transitions + AJAX form loading states.
 * Brand: light theme, glass-blur backdrop, schwarze Spinner-Ring.
 * Mobile-first. Respects prefers-reduced-motion.
 */

:root {
    --vdb-spinner-bg: rgba(255, 255, 255, 0.45);
    --vdb-spinner-blur: 32px;
    /* Snappier transitions — roughly halved so navigation feels instant. */
    --vdb-spinner-fade: 140ms;
    --vdb-main-fade-out: 120ms;
    --vdb-main-fade-in: 180ms;
}

/* ========== Full-screen glass spinner overlay ========== */

.vdb-spinner {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--vdb-spinner-bg);
    -webkit-backdrop-filter: blur(var(--vdb-spinner-blur)) saturate(140%);
    backdrop-filter: blur(var(--vdb-spinner-blur)) saturate(140%);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--vdb-spinner-fade) ease;
}

.vdb-spinner.is-visible {
    opacity: 1;
    pointer-events: auto;
}

.vdb-spinner[hidden] {
    /* Use 'hidden' only before first show — JS removes attr to allow fade-in. */
    display: none;
}

.vdb-spinner-inner {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.vdb-spinner-ring {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    border: 4px solid rgba(0, 0, 0, 0.12);
    border-top-color: rgba(0, 0, 0, 0.85);
    box-sizing: border-box;
    animation: vdb-spin 1s linear infinite;
    filter: drop-shadow(0 4px 12px rgba(0, 0, 0, 0.15));
}

.vdb-spinner-brand {
    font-size: 11px;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: rgba(0, 0, 0, 0.6);
    font-weight: 600;
}

@keyframes vdb-spin {
    from { transform: rotate(0deg); }
    to   { transform: rotate(360deg); }
}

/* ========== Main-content cross-fade on page swap ========== */

main {
    transition:
        opacity var(--vdb-main-fade-out) cubic-bezier(.4,0,.2,1),
        filter  var(--vdb-main-fade-out) cubic-bezier(.4,0,.2,1),
        transform var(--vdb-main-fade-out) cubic-bezier(.4,0,.2,1);
}

main.is-swapping-out {
    opacity: 0;
    filter: blur(6px);
    transform: translateY(-8px);
}

main.is-swapping-in {
    opacity: 0;
    filter: blur(6px);
    transform: translateY(8px);
    transition:
        opacity   var(--vdb-main-fade-in) cubic-bezier(.2,.8,.2,1),
        filter    var(--vdb-main-fade-in) cubic-bezier(.2,.8,.2,1),
        transform var(--vdb-main-fade-in) cubic-bezier(.2,.8,.2,1);
}

/* ========== Button loading state ========== */

.auth-btn.is-loading,
.cta.is-loading,
button.is-loading {
    position: relative;
    color: transparent !important;
    pointer-events: none;
    transform: scale(0.985);
    transition: transform 180ms ease;
    overflow: hidden;
}

.auth-btn.is-loading::after,
.cta.is-loading::after,
button.is-loading::after {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 16px;
    height: 16px;
    margin: -8px 0 0 -8px;
    border-radius: 50%;
    border: 2px solid rgba(255, 255, 255, 0.35);
    border-top-color: rgba(255, 255, 255, 0.95);
    box-sizing: border-box;
    animation: vdb-spin 0.8s linear infinite;
}

.auth-btn.is-loading::before,
.cta.is-loading::before,
button.is-loading::before {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(110deg,
        transparent 30%,
        rgba(255, 255, 255, 0.18) 50%,
        transparent 70%);
    background-size: 200% 100%;
    animation: vdb-btn-shimmer 1.4s linear infinite;
    pointer-events: none;
}

/* Ghost / Google variants use dark spinner */
.auth-btn.ghost.is-loading::after,
.auth-btn.google.is-loading::after {
    border-color: rgba(0, 0, 0, 0.2);
    border-top-color: rgba(0, 0, 0, 0.85);
}

.auth-btn.ghost.is-loading::before,
.auth-btn.google.is-loading::before {
    background: linear-gradient(110deg,
        transparent 30%,
        rgba(0, 0, 0, 0.08) 50%,
        transparent 70%);
    background-size: 200% 100%;
}

@keyframes vdb-btn-shimmer {
    from { background-position: 200% 0; }
    to   { background-position: -100% 0; }
}

/* ========== Input loading shimmer (form-busy) ========== */

form.is-busy {
    pointer-events: none;
}

form.is-busy .auth-field input,
form.is-busy .auth-field select,
form.is-busy .auth-field textarea {
    background-image: linear-gradient(110deg,
        transparent 35%,
        rgba(0, 0, 0, 0.05) 50%,
        transparent 65%);
    background-size: 220% 100%;
    animation: vdb-input-shimmer 1.6s linear infinite;
}

@keyframes vdb-input-shimmer {
    from { background-position: 220% 0; }
    to   { background-position: -120% 0; }
}

/* ========== Skeleton placeholder (for heavy content fetches) ========== */

.vdb-skeleton {
    padding: 1rem;
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.04);
}

.vdb-skeleton-row {
    height: 14px;
    margin: 8px 0;
    border-radius: 6px;
    background: linear-gradient(110deg,
        rgba(0, 0, 0, 0.04) 30%,
        rgba(0, 0, 0, 0.10) 50%,
        rgba(0, 0, 0, 0.04) 70%);
    background-size: 200% 100%;
    animation: vdb-input-shimmer 1.4s linear infinite;
}

.vdb-skeleton-row.w-40 { width: 40%; }
.vdb-skeleton-row.w-60 { width: 60%; }
.vdb-skeleton-row.w-90 { width: 90%; }

/* ========== A11y focus ring on main after swap ========== */

main[tabindex="-1"]:focus {
    outline: none;
}

/* ========== Reduced motion ========== */

@media (prefers-reduced-motion: reduce) {
    .vdb-spinner,
    .vdb-spinner-ring,
    .auth-btn.is-loading,
    .auth-btn.is-loading::after,
    .auth-btn.is-loading::before,
    .cta.is-loading,
    .cta.is-loading::after,
    .cta.is-loading::before,
    button.is-loading,
    button.is-loading::after,
    button.is-loading::before,
    form.is-busy .auth-field input,
    form.is-busy .auth-field select,
    form.is-busy .auth-field textarea,
    .vdb-skeleton-row,
    main {
        animation: none !important;
        transition: none !important;
    }
    .vdb-spinner-ring {
        border-top-color: rgba(0, 0, 0, 0.45);
    }
    main.is-swapping-out,
    main.is-swapping-in {
        opacity: 1;
        filter: none;
    }
}