Html横向排列元素间出现间隔

制作横向排列的若干个div元素时，元素相邻处出现意料外的间隔。

class="wrapper">
        <div class="slider">
            <div class="testimonial">
                <p>This is testimonial 1p>
                <button>Button 1button>
            div>
            <div class="testimonial">
                <p>This is testimonial 2p>
                <button>Button 2button>
            div>
            <div class="testimonial">
                <p>This is testimonial 3p>
                <button>Button 3button>
            div>
            <div class="testimonial">
                <p>This is testimonial 4p>
                <button>Button 4button>
            div>
            <div class="testimonial">
                <p>This is testimonial 5p>
                <button>Button 5button>
            div>
        div>    
    div>

body{
    display: flex;
    min-height: 100vh;
    justify-content: center;
    align-items: center;
}

.wrapper{
    width: 100%;
    overflow: hidden;
    
}

.slider{
    width: 100%;
    white-space: nowrap;
    overflow: hidden;
}

.testimonial{
    background-color: #ededed;
    display: inline-flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 650px;
    height: 130px;
}

.slider{font-size:0}