.quality-section-flat {
    max-width: 1400px;
    margin: 30px auto;
    background-color: #f9fafb;
    border-radius: 24px;
    padding: 30px 20px;
    text-align: center;
}
.section-title-flat {
    font-family: 'Open Sans', sans-serif;
    font-weight: 700;
    font-size: 30px;
    color: #222222;
    margin-bottom: 10px;
}
.section-sub-flat {
    font-family: 'Open Sans', sans-serif;
    font-weight: 400;
    font-size: 15px;
    color: #555555;
    max-width: 700px;
    margin: 0 auto 30px;
}
/* 关键：使用 grid 实现两行三列（桌面端每行三个） */
.quality-grid-flat {
    display: grid;
    grid-template-columns: repeat(3, 1fr);  /* 固定三列 */
    gap: 20px;
}
.quality-card-flat {
    background: #ffffff;
    border-radius: 16px;
    padding: 16px 14px;
    border: 1px solid #e2e8f0;
    transition: box-shadow 0.2s;
    text-align: center;
}
.quality-card-flat:hover {
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}
.quality-icon-flat {
    font-size: 32px;
    margin-bottom: 10px;
}
.quality-card-flat h3 {
    font-family: 'Open Sans', sans-serif;
    font-weight: 700;
    font-size: 18px;
    color: #0047AB;
    margin-bottom: 8px;
}
.quality-card-flat p {
    font-family: 'Open Sans', sans-serif;
    font-weight: 400;
    font-size: 13px;
    color: #555555;
    line-height: 1.4;
}
/* 移动端：自动变为单列 */
@media (max-width: 768px) {
    .quality-section-flat {
        margin: 20px auto;
        padding: 20px 16px;
    }
    .section-title-flat {
        font-size: 24px;
    }
    .section-sub-flat {
        font-size: 14px;
        margin-bottom: 20px;
    }
    .quality-grid-flat {
        grid-template-columns: 1fr;  /* 移动端单列 */
        gap: 12px;
    }
    .quality-card-flat {
        padding: 12px;
    }
}
/* 中等屏幕（例如 900px 以下）可自动调整为两列，避免卡片过窄 */
@media (max-width: 900px) and (min-width: 769px) {
    .quality-grid-flat {
        grid-template-columns: repeat(2, 1fr);
    }
}