/**
 * Skeleton Loaders
 * Auto SEO Pilot - SaaS Platinum Edition v20.4
 * 
 * Skeleton loaders for smooth loading experience without layout shifts
 * 
 * CSS Variables for flexible configuration:
 * --skeleton-gap: Gap between skeleton elements (default: 16px)
 * --skeleton-padding: Padding for skeleton containers (default: 16px)
 * --skeleton-row-gap: Gap between skeleton rows (default: 12px)
 * --skeleton-min-height: Minimum height for skeleton sections (default: 200px)
 * --skeleton-card-padding: Padding for skeleton cards (default: 20px)
 */

:root {
    --skeleton-gap: 16px;
    --skeleton-padding: 16px;
    --skeleton-row-gap: 12px;
    --skeleton-min-height: 200px;
    --skeleton-card-padding: 20px;
    --skeleton-section-padding: 30px;
    --skeleton-icon-size: 50px;
    --skeleton-button-height: 40px;
    --skeleton-button-width: 120px;
}

/* ============================================
   BASE SKELETON ANIMATION
   ============================================ */

@keyframes skeleton-pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

@keyframes skeleton-shimmer {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

/* ============================================
   SKELETON BASE CLASS
   ============================================ */

.skeleton {
    background: linear-gradient(
        90deg,
        var(--bg-secondary) 0%,
        var(--bg-dark) 50%,
        var(--bg-secondary) 100%
    );
    background-size: 200% 100%;
    animation: skeleton-shimmer 1.5s ease-in-out infinite;
    border-radius: 8px;
    position: relative;
    overflow: hidden;
}

.skeleton::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(
        90deg,
        transparent 0%,
        rgba(255, 255, 255, 0.1) 50%,
        transparent 100%
    );
    animation: skeleton-shimmer 1.5s ease-in-out infinite;
}

/* ============================================
   SKELETON VARIANTS
   ============================================ */

.skeleton-text {
    height: 1em;
    margin-bottom: 0.5rem;
}

.skeleton-text-sm {
    height: 0.875rem;
    width: 60%;
}

.skeleton-text-md {
    height: 1rem;
    width: 80%;
}

.skeleton-text-lg {
    height: 1.25rem;
    width: 100%;
}

.skeleton-title {
    height: 1.75rem;
    width: 70%;
    margin-bottom: 1rem;
}

.skeleton-card {
    background: var(--card-bg);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: var(--skeleton-card-padding);
    margin-bottom: var(--skeleton-gap);
}

.skeleton-button {
    height: var(--skeleton-button-height);
    width: var(--skeleton-button-width);
    border-radius: 8px;
}

.skeleton-avatar {
    width: var(--skeleton-icon-size);
    height: var(--skeleton-icon-size);
    border-radius: 50%;
}

.skeleton-image {
    width: 100%;
    height: var(--skeleton-min-height);
    border-radius: 12px;
}

.skeleton-table {
    width: 100%;
}

.skeleton-table-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: 16px;
    padding: 16px 0;
    border-bottom: 1px solid var(--border);
}

.skeleton-table-cell {
    height: 1rem;
}

/* ============================================
   SECTION SKELETON LOADERS
   ============================================ */

.section-skeleton {
    padding: var(--skeleton-section-padding);
    min-height: calc(var(--skeleton-min-height) * 2);
}

.section-skeleton-header {
    display: flex;
    align-items: center;
    gap: var(--skeleton-gap);
    margin-bottom: var(--skeleton-section-padding);
}

.section-skeleton-icon {
    width: var(--skeleton-icon-size);
    height: var(--skeleton-icon-size);
    border-radius: 12px;
}

.section-skeleton-title {
    flex: 1;
}

.section-skeleton-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--skeleton-gap);
    margin-bottom: var(--skeleton-section-padding);
}

.skeleton-card {
    background: var(--card-bg);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: var(--skeleton-card-padding);
}

.section-skeleton-card-header {
    display: flex;
    align-items: center;
    gap: calc(var(--skeleton-gap) * 0.75);
    margin-bottom: calc(var(--skeleton-gap) * 0.9375);
}

.section-skeleton-card-icon {
    width: calc(var(--skeleton-icon-size) * 0.9);
    height: calc(var(--skeleton-icon-size) * 0.9);
    border-radius: 10px;
}

.section-skeleton-card-content {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

/* ============================================
   TABLE SKELETON LOADER
   ============================================ */

.table-skeleton {
    background: var(--card-bg);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: 20px;
    overflow-x: auto;
}

.table-skeleton-header {
    display: grid;
    /* grid-template-columns will be set dynamically via inline style */
    gap: var(--skeleton-gap, 16px);
    padding: var(--skeleton-padding, 16px);
    border-bottom: 2px solid var(--border);
    margin-bottom: var(--skeleton-gap, 16px);
}

.table-skeleton-body {
    display: flex;
    flex-direction: column;
    gap: var(--skeleton-row-gap, 12px);
}

.table-skeleton-row {
    display: grid;
    /* grid-template-columns will be set dynamically via inline style */
    gap: var(--skeleton-gap, 16px);
    padding: var(--skeleton-padding, 16px);
    border-bottom: 1px solid var(--border);
}

/* ============================================
   COMPETITORS SECTION SKELETON
   ============================================ */

.competitors-skeleton {
    padding: var(--skeleton-section-padding);
}

.competitors-skeleton-metrics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--skeleton-gap);
    margin-bottom: var(--skeleton-section-padding);
}

.competitors-skeleton-table {
    background: var(--card-bg);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: var(--skeleton-card-padding);
    overflow-x: auto;
}

/* ============================================
   MODAL SKELETON LOADER
   ============================================ */

.modal-skeleton {
    padding: var(--skeleton-section-padding);
}

.modal-skeleton-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: calc(var(--skeleton-section-padding) * 0.833);
    padding-bottom: var(--skeleton-gap);
    border-bottom: 2px solid var(--border);
}

.modal-skeleton-title {
    height: 1.5rem;
    width: clamp(150px, 25%, 200px);
}

.modal-skeleton-close {
    width: calc(var(--skeleton-icon-size) * 0.64);
    height: calc(var(--skeleton-icon-size) * 0.64);
    border-radius: 8px;
}

.modal-skeleton-content {
    display: flex;
    flex-direction: column;
    gap: var(--skeleton-gap);
}

.modal-skeleton-section {
    background: var(--bg-dark);
    border-radius: 12px;
    padding: var(--skeleton-card-padding);
}

.modal-skeleton-section-title {
    height: 1.25rem;
    width: clamp(120px, 20%, 150px);
    margin-bottom: calc(var(--skeleton-gap) * 0.9375);
}

.modal-skeleton-section-content {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* ============================================
   RESPONSIVE SKELETON
   ============================================ */

@media (max-width: 768px) {
    .section-skeleton-content {
        grid-template-columns: 1fr;
    }
    
    .competitors-skeleton-metrics {
        grid-template-columns: 1fr;
    }
    
    .table-skeleton-header,
    .table-skeleton-row {
        /* grid-template-columns will be set dynamically via inline style */
        min-width: min(90vw, 600px);
    }
}

/* ============================================
   SKELETON UTILITIES
   ============================================ */

.skeleton-hidden {
    display: none;
}

.skeleton-visible {
    display: block;
}

/* Prevent layout shift by reserving space */
.skeleton-reserve-space {
    min-height: var(--skeleton-min-height);
}