/**
 * ===================================
 * 加载动画样式
 * ===================================
 */

/* ---------- 页面加载动画 ---------- */
.page-loader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #ffffff;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    /* CSS 降级：如果 JS 失败或加载缓慢，4 秒后自动淡出 */
    animation: loader-fadeout 0.3s ease 4s forwards;
}

@keyframes loader-fadeout {
    to {
        opacity: 0;
        visibility: hidden;
    }
}

.page-loader.hidden {
    opacity: 0;
    visibility: hidden;
}

.loader-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f1f5f9;
    border-top-color: #667eea;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* ---------- 内容加载骨架屏 ---------- */
.skeleton {
    background: linear-gradient(90deg, #f1f5f9 25%, #e2e8f0 50%, #f1f5f9 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s ease-in-out infinite;
    border-radius: 8px;
}

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

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

.skeleton-title {
    height: 1.5rem;
    width: 60%;
    margin-bottom: 1rem;
}

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

.skeleton-card {
    padding: 1.5rem;
    background: #ffffff;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
}

/* ---------- 图片懒加载动画 ---------- */
img.lazy-loading {
    opacity: 0;
    transition: opacity 0.3s ease;
}

img.lazy-loaded {
    opacity: 1;
}

/* 图片加载占位符 */
.image-placeholder {
    background: #f8fafc;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.image-placeholder::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.5), transparent);
    animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
    to { left: 100%; }
}

/* ---------- 按钮加载状态 ---------- */
.btn-loading {
    position: relative;
    color: transparent !important;
    pointer-events: none;
}

.btn-loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 16px;
    height: 16px;
    margin: -8px 0 0 -8px;
    border: 2px solid currentColor;
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

/* ---------- 脉冲动画 ---------- */
.pulse {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

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

/* ---------- 淡入动画 ---------- */
.fade-in {
    animation: fadeIn 0.5s ease-in;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

/* ---------- 滑入动画 ---------- */
.slide-in-up {
    animation: slideInUp 0.5s ease-out;
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ---------- 缩放动画 ---------- */
.scale-in {
    animation: scaleIn 0.3s ease-out;
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

/* ---------- 加载点动画 ---------- */
.loading-dots {
    display: inline-flex;
    gap: 0.25rem;
}

.loading-dots span {
    width: 6px;
    height: 6px;
    background: currentColor;
    border-radius: 50%;
    animation: dotPulse 1.4s ease-in-out infinite;
}

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

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

@keyframes dotPulse {
    0%, 80%, 100% {
        opacity: 0.3;
        transform: scale(0.8);
    }
    40% {
        opacity: 1;
        transform: scale(1);
    }
}

/* ---------- 旋转加载 ---------- */
.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid currentColor;
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

.spinner-lg {
    width: 40px;
    height: 40px;
    border-width: 4px;
}

/* ---------- 内容加载状态 ---------- */
.content-loading {
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.content-loading .spinner {
    width: 40px;
    height: 40px;
    border-width: 4px;
    border-color: #e2e8f0;
    border-top-color: #667eea;
}