/**
 * Nebula Theme - Skeleton Loading & Loading States
 * Version: 2.0.0
 * 骨架屏和加载动画样式
 */

/* ============================
   Skeleton Screen Base
   ============================ */

.skeleton {
    background: linear-gradient(
        90deg,
        var(--nebula-bg-secondary, #F8FAFC) 25%,
        var(--nebula-bg-tertiary, #F1F5F9) 50%,
        var(--nebula-bg-secondary, #F8FAFC) 75%
    );
    background-size: 200% 100%;
    animation: skeleton-shimmer 1.5s ease-in-out infinite;
    border-radius: var(--nebula-radius-sm, 4px);
}

[data-theme="dark"] .skeleton,
body.dark-mode .skeleton {
    background: linear-gradient(
        90deg,
        var(--nebula-bg-tertiary, #1E293B) 25%,
        var(--nebula-bg-secondary, #334155) 50%,
        var(--nebula-bg-tertiary, #1E293B) 75%
    );
    background-size: 200% 100%;
}

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

/* Skeleton text */
.skeleton-text {
    height: 1em;
    margin-bottom: 0.5em;
}

.skeleton-text--title {
    height: 1.5em;
    width: 80%;
    margin-bottom: 0.75em;
}

.skeleton-text--short {
    width: 40%;
}

/* Skeleton image */
.skeleton-image {
    width: 100%;
    padding-top: 56.25%; /* 16:9 aspect ratio */
    position: relative;
}

.skeleton-image--square {
    padding-top: 100%;
}

.skeleton-image--circle {
    padding-top: 0;
    width: 60px;
    height: 60px;
    border-radius: 50%;
}

/* ============================
   Article Card Skeleton
   ============================ */

.article-skeleton {
    background: var(--nebula-bg, #FFFFFF);
    border-radius: var(--nebula-radius-xl, 16px);
    overflow: hidden;
    box-shadow: var(--nebula-shadow-card, 0 4px 20px rgba(0, 0, 0, 0.08));
}

.article-skeleton__image {
    width: 100%;
    padding-top: 56.25%;
    position: relative;
}

.article-skeleton__content {
    padding: 20px;
}

.article-skeleton__title {
    height: 1.5em;
    width: 90%;
    margin-bottom: 12px;
}

.article-skeleton__excerpt {
    height: 1em;
    width: 100%;
    margin-bottom: 8px;
}

.article-skeleton__excerpt:last-child {
    width: 60%;
}

.article-skeleton__meta {
    display: flex;
    gap: 12px;
    margin-top: 16px;
}

.article-skeleton__meta-item {
    height: 1em;
    width: 60px;
}

/* ============================
   Loading Spinner
   ============================ */

.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid var(--nebula-border, #E2E8F0);
    border-top-color: var(--nebula-primary, #0EA5E9);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Large spinner */
.loading-spinner--lg {
    width: 40px;
    height: 40px;
    border-width: 3px;
}

/* ============================
   Loading Button States
   ============================ */

.btn--loading {
    position: relative;
    pointer-events: none;
    opacity: 0.8;
}

.btn--loading::after {
    content: '';
    position: absolute;
    top: 50%;
    right: 12px;
    transform: translateY(-50%);
    width: 16px;
    height: 16px;
    border: 2px solid currentColor;
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

/* ============================
   Load More Enhanced
   ============================ */

.ds-load-more {
    text-align: center;
    padding: 24px;
    color: var(--nebula-text-secondary, #64748B);
    cursor: pointer;
    font-weight: var(--nebula-font-medium, 500);
    transition: color var(--nebula-duration-fast, 0.15s);
}

.ds-load-more:hover {
    color: var(--nebula-primary, #0EA5E9);
}

.ds-load-more.is-loading {
    pointer-events: none;
    color: var(--nebula-primary, #0EA5E9);
}

.ds-load-more.is-loading .ds-load-more__text::after {
    content: '';
    display: inline-block;
    width: 14px;
    height: 14px;
    margin-left: 8px;
    border: 2px solid var(--nebula-primary, #0EA5E9);
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    vertical-align: middle;
}

/* ============================
   Page Loading Overlay
   ============================ */

.page-loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--nebula-bg, #FFFFFF);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.3s ease;
}

.page-loading-overlay.is-hidden {
    opacity: 0;
    pointer-events: none;
}

.page-loading-overlay__spinner {
    width: 48px;
    height: 48px;
    border: 3px solid var(--nebula-border, #E2E8F0);
    border-top-color: var(--nebula-primary, #0EA5E9);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

/* ============================
   Inline Loading Dots
   ============================ */

.loading-dots {
    display: inline-flex;
    gap: 4px;
    align-items: center;
}

.loading-dots__dot {
    width: 6px;
    height: 6px;
    background: var(--nebula-text-muted, #94A3B8);
    border-radius: 50%;
    animation: loading-dot-pulse 1.4s ease-in-out infinite;
}

.loading-dots__dot:nth-child(2) {
    animation-delay: 0.2s;
}

.loading-dots__dot:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes loading-dot-pulse {
    0%, 80%, 100% {
        transform: scale(0.6);
        opacity: 0.5;
    }
    40% {
        transform: scale(1);
        opacity: 1;
    }
}

/* Dark mode dots */
[data-theme="dark"] .loading-dots__dot,
body.dark-mode .loading-dots__dot {
    background: var(--nebula-text-muted, #64748B);
}