渐变的本质： 绘制一张背景图片，所以使用 background 或者 background-image
background 的诸多属性，渐变都是可以使用的（repeat，position）
百分比： 把元素渐变方向的整体长度看成 100%
线性渐变背景
使用： （至少三个参数，从第二个参数开始，都是颜色）background-image: linear-gradient( 方向 开始颜色 结束颜色);方向默认值（从上到下）
background-image: linear-gradient(#000, #fff);
to right 到右
background-image: linear-gradient(to right, #000, #fff);background-image: linear-gradient(to left, #000, #fff);background-image: linear-gradient(to top, #000, #fff);background-image: linear-gradient(to bottom, #000, #fff);
to right bottom 到右下角
background-image: linear-gradient(to right bottom, #000, #fff);background-image: linear-gradient(to right top, #000, #fff);background-image: linear-gradient(to left top, #000, #fff);background-image: linear-gradient(to left bottom, #000, #fff);
角度 deg
background-image: linear-gradient(0deg, #000, #fff);background-image: linear-gradient(90deg, #000, #fff);background-image: linear-gradient(180deg, #000, #fff);background-image: linear-gradient(270deg, #000, #fff);background-image: linear-gradient(45deg, #000, #fff);background-image: linear-gradient(135deg, #000, #fff);background-image: linear-gradient(225deg, #000, #fff);background-image: linear-gradient(315deg, #000, #fff);background-image: linear-gradient(-45deg #000, #fff);background-image: linear-gradient(-90deg #000, #fff);
颜色结点
background-image: linear-gradient(red %10， green 20%， blue 30%, yellow 40%);/*从 0% 到 10% 为 red从 10% 到 20% 为 red 到 green 的渐变从 20% 到 30% 为 green 到 blue 的渐变从 30% 到 40% 为 blue 到 yellow 的渐变从 40% 到 100% 为 yellow 最后一个颜色百分比不写，默认到 100%第一个颜色百分比不写，默认 0%*/
应用：45 度红白格（马赛克地砖）明确的 颜色分割线（red 25%, white 25%）多重渐变背景，以逗号隔开，适当位置设置透明颜色123
重复的线性渐变 background-image: repeating-linear-gradient(45deg, red 0%, white 20%);
颜色结点，除了可以写百分值，还可以写一个具体的像素值。写像素值，必须写两个值：起始和结束。
background-image: repeating-linear-gradient(45deg, white 0px, white 10px, red 10px, red 20px; // 发廊灯
<!DOCTYPE html><html><head><meta charset="UTF-8" /><title></title><style type="text/css">body {width: 100%;color: #000;background: #96b377;font: 14px Helvetica, Arial, sans-serif;}#outer_box {width: 100px;height: 300px;margin: 300px auto 0;overflow: hidden}#inner_box {width: 100px;height: 3000px;margin-top: -900px;background-image: repeating-linear-gradient(155deg, red 0px, red 20px, black 20px, black 40px);}#inner_box:hover {margin-top: 0px;transition: 9s;}</style></head><body><div id="outer_box"><div id="inner_box"></div></div></body></html>
文字光斑 动画文字要设置透明 color: rgba(255, 255, 255, 0.3);3
径向渐变背景 background-image: radia-gradient(形状尺寸, 开始颜色, 结束颜色);
从起点到终点，颜色从内向外渐变。
形状尺寸参数circle 默认形状，圆形当 width 相等 height 时，总是圆形当 width ！= height 时，是椭圆颜色结点百分比，参照圆心到最远端的距离尺寸大小closest-side circle 最近边farthest-side circle 最远边closest-corner 最近角farthest-corner 最远角at 设置圆心 background-image: radial-gradient(closest-corner circle at 50px 50px, olive, red);background-image: radial-gradient(closest-corner circle at 50px 50px, olive, red);重复的径向渐变 background-image: repeating-radial-gradient(red 0%, olive 25%); background-image: repeating-radial-gradient(red 0%, olive 25%, blue 50%);
