* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: "Microsoft YaHei", sans-serif; background: #f0f2f5; }
.flash { padding: 12px 20px; border-radius: 8px; margin-bottom: 20px; text-align: center; font-size: 14px; display: flex; align-items: center; justify-content: center; gap: 8px; box-shadow: 0 2px 8px rgba(0,0,0,0.08); animation: flashIn 0.4s ease; transition: opacity 0.5s ease, max-height 0.5s ease, margin 0.5s ease, padding 0.5s ease; }
.flash.success { background: linear-gradient(135deg, #d4edda, #c3e6cb); color: #155724; border-left: 4px solid #28a745; }
.flash.error { background: linear-gradient(135deg, #f8d7da, #f5c6cb); color: #721c24; border-left: 4px solid #dc3545; }
.flash .flash-icon { font-size: 16px; flex-shrink: 0; }
.flash.fade-out { opacity: 0; max-height: 0; padding-top: 0; padding-bottom: 0; margin-bottom: 0; overflow: hidden; }
@keyframes flashIn { from { opacity: 0; transform: translateY(-10px); } to { opacity: 1; transform: translateY(0); } }

.back-button {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: #666;
    text-decoration: none;
    font-size: 14px;
    padding: 8px 16px;
    border-radius: 20px;
    background: #f5f5f5;
    transition: all 0.3s ease;
    font-weight: 500;
    user-select: none;
}

.back-button:hover {
    color: #4CAF50;
    background: #e8f5e9;
    transform: translateX(-3px);
    box-shadow: 0 2px 8px rgba(76, 175, 80, 0.2);
}

.back-button::before {
    content: '←';
    font-size: 16px;
    font-weight: bold;
    transition: transform 0.3s ease;
}

.back-button:hover::before {
    transform: translateX(-3px);
}

.back-button:active {
    transform: scale(0.95);
}