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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              @import "compass/css3";

html {
  background: #222;
  padding: 30px;
}

#grid {
  position: absolute;
  left: 50%;
  margin-left: -200px;
  @include transition(all 500ms);
}

#grid div {
  position: absolute;
  background: #feffe7;
  box-sizing: border-box;
  @include transition(all);
}
            
          
!
            
              function Block (i) {
    this.w = Math.round(Math.random() * 3) || 1;
    this.h = Math.round(Math.random() * 3) || 1;
    this.dom = $('<div>').css({
        width : this.w * 10 - 2,
        height : this.h * 10 - 2,
        transition : 'all 300ms ' + i + 'ms'
    });
    $('#grid').append(this.dom);
}

Block.prototype = {
    setPosition : function (x, y) {
        this.dom.css({
            top : y * 10,
            left : x * 10
        });
    }
}


function Grid () {
    this.blocks = [];
    this.grid = [];
}

Grid.prototype = {
    columns : 40,

    add : function (block) {
        this.blocks.push(block);
        this.findPlace(block);
    },

    clear : function () {
        var x, y;
        for (y = 0; y < this.grid.length; y++) {
            for (x = 0; x < this.grid[y].length; x++) {
                this.grid[y][x] = false;
            }
        }
        this.firstEmpty = 0;
    },

    firstEmpty : 0,
    findPlace : function (block) {
        var x, y,
            maxX = this.columns - block.w,
            maxY = this.grid.length + block.h;

        for (y = this.firstEmpty; y < maxY; y++) {
            for (x = 0; x <= maxX; x++) {
                if (this.place(block, x, y)) {
                    return;
                }
            }
        }
    },

    place : function (block, x, y) {
        var i, j,
            w = block.w,
            h = block.h;
        // check if we can place it
        for (i = 0; i < h; i++) {
            if (!this.grid[y + i]) {
                this.grid[y + i] = [];
            }
            for (j = 0; j < w; j++) {
                if (this.grid[y + i][x + j]) {
                    return false;
                }
            }
        }
        // we can place it, do so now
        for (i = 0; i < h; i++) {
            for (j = 0; j < w; j++) {
                this.grid[y + i][x + j] = true;
            }
        }
        block.setPosition(x, y);
        this.updateFirstEmpty();
        // return true so we know we placed the block
        return true;
    },

    updateFirstEmpty : function () {
        var x, y, hasEmpty;
        for (y = this.firstEmpty; y < this.grid.length; y++) {
            hasEmpty = false;
            for (x = 0; x < this.columns; x++) {
                if (!this.grid[y][x]) {
                    hasEmpty = true;
                }
            }
            if (hasEmpty) {
                this.firstEmpty = y;
                return;
            }
        }
    },

    setColumns : function (columns) {
        var i, block;
        if (columns === this.columns) {
            return;
        }
        $('#grid').css('margin-left', -columns * 5);
        this.columns = columns;
        this.clear();
        for (i = 0; i < this.blocks.length; i++) {
            this.findPlace(this.blocks[i], i);
        }
    }
}

var grid = new Grid();

for (var i = 0; i < 300; i++) {
    grid.add(new Block(i));
}


// change column count every second

var lastChange = +new Date();
function changeColumns() {
    var now = +new Date();
    var columns; 
    requestAnimationFrame(changeColumns);
    if (now - lastChange > 1000) {
        lastChange = now;
        columns = 10 + Math.round(Math.random() * 60);
        if (grid.columns === columns) {
            columns ++;
        }
        grid.setColumns(columns);
    }
}

changeColumns();
            
          
!
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