/**
 * 朴新教育官网 v5.2 - 占位图片样式
 * 使用CSS渐变作为图片占位，后续可替换为真实图片
 */

/* ==================== Banner占位图 ==================== */
.placeholder-banner {
    position: relative;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

.placeholder-banner-1 {
    background: linear-gradient(135deg, #0A6ED4 0%, #1e40af 50%, #0f172a 100%);
}

.placeholder-banner-2 {
    background: linear-gradient(135deg, #0891b2 0%, #0e7490 50%, #164e63 100%);
}

.placeholder-banner-3 {
    background: linear-gradient(135deg, #7c3aed 0%, #5b21b6 50%, #4c1d95 100%);
}

/* Banner装饰元素 */
.placeholder-banner::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 80%;
    height: 200%;
    background: radial-gradient(ellipse, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: bannerGlow 8s ease-in-out infinite;
}

.placeholder-banner::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 40%;
    background: linear-gradient(to top, rgba(0,0,0,0.3), transparent);
}

@keyframes bannerGlow {
    0%, 100% { transform: translateX(0) rotate(0deg); opacity: 0.5; }
    50% { transform: translateX(-30px) rotate(5deg); opacity: 0.8; }
}

/* ==================== 课程封面占位图 ==================== */
.placeholder-course {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(145deg, #f8fafc 0%, #e2e8f0 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-course::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #0A6ED4, #0891b2);
}

.placeholder-course-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #0A6ED4, #0891b2);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 36px;
    color: white;
    box-shadow: 0 10px 40px rgba(10, 110, 212, 0.3);
}

/* 不同课程的配色 */
.placeholder-course-math { --course-color: #0A6ED4; }
.placeholder-course-english { --course-color: #0891b2; }
.placeholder-course-chinese { --course-color: #7c3aed; }
.placeholder-course-physics { --course-color: #059669; }
.placeholder-course-chemistry { --course-color: #dc2626; }
.placeholder-course-biology { --course-color: #16a34a; }
.placeholder-course-history { --course-color: #d97706; }
.placeholder-course-geography { --course-color: #0891b2; }
.placeholder-course-politics { --course-color: #7c3aed; }
.placeholder-course-fulltime { --course-color: #0f172a; }
.placeholder-course-art { --course-color: #db2777; }
.placeholder-course-ket { --course-color: #ea580c; }

/* ==================== 校区图片占位图 ==================== */
.placeholder-campus {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(145deg, #f1f5f9 0%, #cbd5e1 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-campus::before {
    content: '';
    position: absolute;
    width: 120%;
    height: 120%;
    background: 
        radial-gradient(circle at 20% 80%, rgba(10, 110, 212, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(8, 145, 178, 0.1) 0%, transparent 50%);
}

.placeholder-campus-icon {
    width: 100px;
    height: 100px;
    background: linear-gradient(135deg, #e2e8f0, #cbd5e1);
    border-radius: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 48px;
    color: #64748b;
    box-shadow: 
        0 4px 6px -1px rgba(0,0,0,0.1),
        0 2px 4px -1px rgba(0,0,0,0.06),
        inset 0 2px 4px rgba(255,255,255,0.5);
}

/* ==================== 教师头像占位图 ==================== */
.placeholder-teacher {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(145deg, #f8fafc 0%, #e2e8f0 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-avatar {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 48px;
    font-weight: 700;
    color: white;
    text-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

/* 教师头像配色 */
.placeholder-teacher-1 .placeholder-avatar { background: linear-gradient(135deg, #0A6ED4, #1e40af); }
.placeholder-teacher-2 .placeholder-avatar { background: linear-gradient(135deg, #0891b2, #0e7490); }
.placeholder-teacher-3 .placeholder-avatar { background: linear-gradient(135deg, #7c3aed, #5b21b6); }
.placeholder-teacher-4 .placeholder-avatar { background: linear-gradient(135deg, #059669, #047857); }
.placeholder-teacher-5 .placeholder-avatar { background: linear-gradient(135deg, #dc2626, #b91c1c); }
.placeholder-teacher-6 .placeholder-avatar { background: linear-gradient(135deg, #d97706, #b45309); }
.placeholder-teacher-7 .placeholder-avatar { background: linear-gradient(135deg, #db2777, #be185d); }
.placeholder-teacher-8 .placeholder-avatar { background: linear-gradient(135deg, #4f46e5, #4338ca); }

/* ==================== 新闻封面占位图 ==================== */
.placeholder-news {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(145deg, #f8fafc 0%, #e2e8f0 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-news::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 100%;
    background: 
        linear-gradient(135deg, transparent 40%, rgba(10, 110, 212, 0.05) 50%, transparent 60%),
        linear-gradient(-135deg, transparent 40%, rgba(10, 110, 212, 0.05) 50%, transparent 60%);
    background-size: 20px 20px;
}

.placeholder-news-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #e2e8f0, #cbd5e1);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    color: #64748b;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

/* ==================== Logo占位图 ==================== */
.placeholder-logo {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #0A6ED4, #0891b2);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: 700;
    color: white;
    border-radius: 8px;
}

/* ==================== 关于我们占位图 ==================== */
.placeholder-about {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(145deg, #f8fafc 0%, #e2e8f0 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-about::before {
    content: '';
    position: absolute;
    width: 200%;
    height: 200%;
    background: 
        radial-gradient(circle at 30% 30%, rgba(10, 110, 212, 0.08) 0%, transparent 40%),
        radial-gradient(circle at 70% 70%, rgba(8, 145, 178, 0.08) 0%, transparent 40%);
}

.placeholder-about-icon {
    width: 120px;
    height: 120px;
    background: linear-gradient(135deg, #0A6ED4, #0891b2);
    border-radius: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 60px;
    color: white;
    box-shadow: 0 20px 60px rgba(10, 110, 212, 0.3);
}

/* ==================== OG图片占位图 ==================== */
.placeholder-og {
    position: relative;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #0A6ED4 0%, #1e40af 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-og::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: 
        radial-gradient(circle at 30% 30%, rgba(255,255,255,0.1) 0%, transparent 30%),
        radial-gradient(circle at 70% 70%, rgba(255,255,255,0.05) 0%, transparent 30%);
}

.placeholder-og-content {
    position: relative;
    z-index: 1;
    text-align: center;
    color: white;
}

.placeholder-og-title {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 16px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.placeholder-og-subtitle {
    font-size: 24px;
    opacity: 0.9;
}

/* ==================== 通用动画效果 ==================== */
.placeholder-shimmer {
    position: relative;
    overflow: hidden;
}

.placeholder-shimmer::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        90deg,
        transparent 0%,
        rgba(255,255,255,0.4) 50%,
        transparent 100%
    );
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { left: -100%; }
    100% { left: 100%; }
}

/* ==================== 响应式适配 ==================== */
@media (max-width: 768px) {
    .placeholder-banner-icon {
        width: 60px;
        height: 60px;
        font-size: 28px;
    }
    
    .placeholder-course-icon {
        width: 60px;
        height: 60px;
        font-size: 28px;
    }
    
    .placeholder-campus-icon {
        width: 80px;
        height: 80px;
        font-size: 36px;
    }
    
    .placeholder-avatar {
        font-size: 36px;
    }
    
    .placeholder-about-icon {
        width: 80px;
        height: 80px;
        font-size: 40px;
    }
    
    .placeholder-og-title {
        font-size: 32px;
    }
    
    .placeholder-og-subtitle {
        font-size: 18px;
    }
}