* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html,
body {
    width: 100%;
    overflow-x: hidden;
    font-family: "SF Pro SC", "SF Pro Display", "SF Pro Icons", "PingFang SC", "Helvetica Neue", "Helvetica", "Arial", sans-serif;
    font-size: 16px;
    color: #444546;
}


header {
    width: 100%;
    max-width: 1200px;
    margin: 50px auto;
    height: 50px;
    display: flex;
    align-items: center;
    padding: 0 20px;
}



header .logo {
    max-width: 280px;
    display: flex;
    align-items: center;
    justify-content: center;
}




h1 {
    width: 100%;
    max-width: 1280px;
    margin: 100px auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 50px;
    color: #1B79FF;
    text-align: center;
    line-height: 60px;
}


h2 {
    width: 100%;
    max-width: 1280px;
    margin: 150px auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 60px;
    color: #000000;
    text-align: center;
    line-height: 70px;
}



h3 {
    width: 100%;
    max-width: 1000px;
    margin: 20px auto;
    padding: 0 20px;
    font-size: 25px;
    color: #1B79FF;
}



.problem-list h4 {
    font-size: 30px;
    color: #9f9f9f;
    text-align: left;
    line-height: 40px;
    padding: 0;
    margin: 0;
}



.zhutupailie {
    width: 100%;
    /* 改为视口宽度，满屏 */
    max-width: none;
    /* 取消最大宽度限制 */
    margin: 0 auto;
    /* 居中但宽度已为 100vw */
    height: auto;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    /* 防止图片超出产生滚动条 */
}

/* 四图水平无缝排列，高度 400px */
.zhutupailie .zhutu-row {
    display: flex;
    flex-direction: row;
    padding: 0;
    margin: 0;
    gap: 5px;
    /* 改为 5px 间隔 */
    width: 100%;
}

.zhutupailie .zhutu-row img {
    height: 400px;
    /* 固定高度 */
    flex: 1 1 0;
    /* 四张等分并撑满容器 */
    object-fit: cover;
    /* 裁切并保持填充，无留白 */
    display: block;
    border: none;
    margin: 0;
    padding: 0;
}


.changjingtupian {
    width: 100%;
    max-width: 1000px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 100px auto 30px auto;
    padding: 0 20px;
}

.changjingtupian img {
    width: 100%;
    max-width: 1000px;
    height: auto;
    min-height: 400px;
    object-fit: cover;
    display: block;
    border-radius: 10px;
}




p {
    width: 100%;
    max-width: 800px;
    margin: 20px auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    color: #000000;
}


.chanpinwendang {
    width: 100%;
    max-width: 1000px;
    margin: 100px auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.chakanwendang {
    width: 400px;
    height: 60px;
    background-color: #1B79FF;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.chanpinwendang a {
    text-decoration: none;
    font-size: 20px;
    color: #ffffff
}


footer {
    width: 100%;
    margin: 200px auto 10px auto;
    color: #888888;
    font-size: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    /* 如果需要同时水平居中 */
    height: 50px;
    /* 示例高度 */

}




/* 鼠标选中文字显示蓝色（兼容浏览器）*/
::selection {
    background: #007bff;
    /* 蓝色背景 */
    color: #ffffff;
    /* 白色文字 */
}

::-moz-selection {
    background: #007bff;
    color: #ffffff;
}

.problem-list {
    width: 100%;
    max-width: 1000px;
    margin: 100px auto;
    padding-left: 20px;
    padding-right: 20px;
    border-left: 10px solid #1B79FF;
}

/* 平板端适配 (768px - 1024px) */
@media screen and (max-width: 1024px) {
    h1 {
        font-size: 36px;
        line-height: 48px;
        margin: 60px auto;
    }

    h2 {
        font-size: 40px;
        line-height: 50px;
        margin: 80px auto;
    }

    h3 {
        font-size: 22px;
    }

    .problem-list h4 {
        font-size: 24px;
        line-height: 36px;
    }

    .zhutupailie .zhutu-row img {
        height: 300px;
    }

    .changjingtupian {
        margin: 60px auto 20px auto;
    }

    .changjingtupian img {
        min-height: 300px;
    }

    p {
        font-size: 18px;
    }
}

/* 手机端适配 (最大 767px) */
@media screen and (max-width: 767px) {
    header {
        height: 40px;
        padding: 0 15px;
    }

    header .logo {
        max-width: 120px;
    }

    h1 {
        font-size: 24px;
        line-height: 32px;
        margin: 40px auto;
        padding: 0 15px;
    }

    h2 {
        font-size: 28px;
        line-height: 36px;
        margin: 60px auto;
        padding: 0 15px;
    }

    h3 {
        font-size: 18px;
        padding: 0 15px;
    }

    .problem-list {
        margin: 60px auto;
        padding-left: 15px;
        padding-right: 15px;
        border-left: 5px solid #1B79FF;
    }

    .problem-list h4 {
        font-size: 16px;
        line-height: 28px;
    }

    .zhutupailie .zhutu-row {
        flex-direction: column;
        gap: 5px;
    }

    .zhutupailie .zhutu-row img {
        height: 200px;
        width: 100%;
    }

    .changjingtupian {
        margin: 40px auto 20px auto;
        padding: 0 15px;
    }

    .changjingtupian img {
        min-height: 200px;
        border-radius: 5px;
    }

    p {
        font-size: 16px;
        padding: 0 15px;
    }

    footer {
        font-size: 10px;
        margin: 100px auto 10px auto;
        padding: 0 15px;
        text-align: center;
        height: auto;
        line-height: 20px;
    }
}

/* 小屏手机适配 (最大 375px) */
@media screen and (max-width: 375px) {
    h1 {
        font-size: 20px;
        line-height: 28px;
    }

    h2 {
        font-size: 24px;
        line-height: 32px;
    }

    .problem-list h4 {
        font-size: 14px;
        line-height: 24px;
    }

    .zhutupailie .zhutu-row img {
        height: 150px;
    }

    p {
        font-size: 14px;
    }
}