为什么chart.js画布不尊重容器元素的填充？

我使用Chart.js和简单的折线图,但Chart.js计算的宽度和高度属性似乎是基于忽略填充的父元素的总宽度和高度.

var optiOns= {
    maintainAspectRatio: false,
    responsive: true
};

var data = {
    labels: ["", "", "", "", "", "", ""],
    datasets: [
        {
            label: "My First dataset",
            fillColor: "rgba(220,220,220,0.2)",
            strokeColor: "rgba(220,220,220,1)",
            pointColor: "rgba(220,220,220,1)",
            pointStrokeColor: "#fff",
            pointHighlightFill: "#fff",
            pointHighlightStroke: "rgba(220,220,220,1)",
            data: [65, 59, 80, 81, 56, 55, 40]
        },
        {
            label: "My Second dataset",
            fillColor: "rgba(151,187,205,0.2)",
            strokeColor: "rgba(151,187,205,1)",
            pointColor: "rgba(151,187,205,1)",
            pointStrokeColor: "#fff",
            pointHighlightFill: "#fff",
            pointHighlightStroke: "rgba(151,187,205,1)",
            data: [28, 48, 40, 19, 86, 27, 90]
        }
    ]
};

var ctx1 = document.getElementById("mychart1").getContext("2d");
var myNewChart = new Chart(ctx1).Line(data, options);

.container {
    padding: 15px 15px 15px 15px;
    width: 300px;
    height: 200px;
    border: 1px solid black;
}

.child {
    display: inline-block;
    border: 1px solid red;
    width:100%;
    height:100%;
}

    




    
test