小编son*_*ouf的帖子

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/css/bootstrap.css" rel="stylesheet"/>
   <div class="container">
        <div class="row">
          <div class="col-md-8 col-lg-6 B"><div class="card card-inverse" style="background-color: #333; border-color: #333;">
    <img src="http://lorempicsum.com/rio/800/500/4" class="img-fluid" alt="Responsive image">
    
    </div></div>
      <div class="col-md-4 col-lg-3 G">
          <div class="row">
          <div class="col-md-6 col-lg-6 B"><div class="card card-inverse" style="background-color: #333; border-color: #333;">
    <img src="http://lorempicsum.com/rio/800/500/4" class="img-fluid" alt="Responsive image">
    
    </div></div>
       <div class="col-md-6 col-lg-6 B"><div class="card card-inverse" style="background-color: #333; border-color: #333;">
    <img src="http://lorempicsum.com/rio/800/500/4" class="img-fluid" alt="Responsive image">
    
    </div></div>
       <div class="col-md-12"><div class="card card-inverse" style="background-color: #333; border-color: #333;">
    <img src="http://lorempicsum.com/rio/800/500/3" class="img-fluid" alt="Responsive image">
    
    </div></div>
       </div>
    </div> …

a {
  color:#00f;
  text-decoration:none;
  display:inline-block;
}
a:after {
  width: 0;
  display:block;
  background:#00f;
  height:3px;
  transition: all .5s ease-in-out;
  content:"";
}
a:hover {
  color:#00f;
}
a:hover:after {
  width:100%;
}

<a href="#">Click first</a>
<a href="#">Click second</a>

#content {
  -ms-box-orient: horizontal;
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -moz-flex;
  display: -webkit-flex;
  display: flex;
  -webkit-justify-content: space-around;
  justify-content: space-around;
  -webkit-flex-flow: row wrap;
  flex-flow: row wrap;
  -webkit-align-items: stretch;
  align-items: stretch;
}
.box {
  flex-grow: 1;
  flex-shrink: 0;
  border: 3px solid rgba(0, 0, 0, .2);
}
.box1 {
  flex-grow: 1;
  flex-shrink: 0;
  border: 3px solid rgba(0, 0, 0, .2);
}

<h4>it shinks with a flex-shrink of 0</h4>
<div id="content">
  <div class="box" style="background-color:red;">A</div>
  <div class="box" …

@keyframes strike {
  0% {
    width: 0;
  }
  50% {
    width: 100%;
  }
  100% {
    width: 0;
  }
}

.strike {
  position: relative;
}

.strike:hover:after {
  content: ' ';
  position: absolute;
  top: 50%;
  left: 0;
  width: 100%;
  height: 1px;
  background: black;
  animation-name: strike;
  animation-duration: 1s;
  animation-timing-function: linear;
  animation-iteration-count: 1;
  animation-fill-mode: fill;
  animation-direction: normal;
}

<div>
  The text in the span <span class="strike">is what I want to strike out</span>.
</div>

class Vec {
  constructor(x = 0, y = 0) {
    this.x = x;
    this.y = y;
  }
}

class Rect {
  constructor(w, h) {
    this.pos = new Vec;
    this.size = new Vec(w, h)
  }
  get left() {
    return this.pos.x - this.size.x / 2;
  }
  get right() {
    return this.pos.x - this.size.x / 2;
  }
  get top() {
    return …

var canvas=document.getElementById("canvas");
var context=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
function reOffset(){
  var BB=canvas.getBoundingClientRect();
  offsetX=BB.left;
  offsetY=BB.top;        
}
var offsetX,offsetY;
reOffset();
window.onscroll=function(e){ reOffset(); }

context.lineWidth=2;
context.strokeStyle='blue';

var coordinates = [];
var isDone=false;

$('#done').click(function(){
  isDone=true;
});

$("#canvas").mousedown(function(e){handleMouseDown(e);});

function handleMouseDown(e){
  if(isDone || coordinates.length>10){return;}

  // tell the browser we're handling this event
  e.preventDefault();
  e.stopPropagation();

  mouseX=parseInt(e.clientX-offsetX);
  mouseY=parseInt(e.clientY-offsetY);
  coordinates.push({x:mouseX,y:mouseY});
  drawPolygon();
}

function drawPolygon(){
  context.clearRect(0,0,cw,ch);
  context.beginPath();
  context.moveTo(coordinates[0].x, coordinates[0].y);
  for(index=1; index<coordinates.length;index++) {
    context.lineTo(coordinates[index].x, coordinates[index].y);
  }
  context.closePath();
  context.stroke();
}

body{ background-color: ivory; }
#canvas{border:1px …