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Vào thẳng vắn đề luôn 👇

Bước 1: Vào tab Mẫu, chọn chỉnh sửa HTML và tìm đoạn </head>

Bước 2: Copy toàn bộ code dưới thêm trên thẻ mới tìm được:

<canvas height='953' id='canvas' style='cursor: crosshair;position: fixed;width: 100%;background: #222;margin-top: -25px;' width='1920'/>
<script type='text/javascript'>
//<![CDATA[
// when animating on canvas, it is best to use requestAnimationFrame instead of setTimeout or setInterval
// not supported in all browsers though and sometimes needs a prefix, so we need a shim
window.requestAnimFrame = ( function() {
 return window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    function( callback ) {
     window.setTimeout( callback, 1000 / 60 );
    };
})();

// now we will setup our basic variables for the demo
var canvas = document.getElementById( 'canvas' ),
  ctx = canvas.getContext( '2d' ),
  // full screen dimensions
  cw = window.innerWidth,
  ch = window.innerHeight,
  // firework collection
  fireworks = [],
  // particle collection
  particles = [],
  // starting hue
  hue = 120,
  // when launching fireworks with a click, too many get launched at once without a limiter, one launch per 5 loop ticks
  limiterTotal = 5,
  limiterTick = 0,
  // this will time the auto launches of fireworks, one launch per 80 loop ticks
  timerTotal = 80,
  timerTick = 0,
  mousedown = false,
  // mouse x coordinate,
  mx,
  // mouse y coordinate
  my;
  
// set canvas dimensions
canvas.width = cw;
canvas.height = ch;

// now we are going to setup our function placeholders for the entire demo

// get a random number within a range
function random( min, max ) {
 return Math.random() * ( max - min ) + min;
}

// calculate the distance between two points
function calculateDistance( p1x, p1y, p2x, p2y ) {
 var xDistance = p1x - p2x,
   yDistance = p1y - p2y;
 return Math.sqrt( Math.pow( xDistance, 2 ) + Math.pow( yDistance, 2 ) );
}

// create firework
function Firework( sx, sy, tx, ty ) {
 // actual coordinates
 this.x = sx;
 this.y = sy;
 // starting coordinates
 this.sx = sx;
 this.sy = sy;
 // target coordinates
 this.tx = tx;
 this.ty = ty;
 // distance from starting point to target
 this.distanceToTarget = calculateDistance( sx, sy, tx, ty );
 this.distanceTraveled = 0;
 // track the past coordinates of each firework to create a trail effect, increase the coordinate count to create more prominent trails
 this.coordinates = [];
 this.coordinateCount = 3;
 // populate initial coordinate collection with the current coordinates
 while( this.coordinateCount-- ) {
  this.coordinates.push( [ this.x, this.y ] );
 }
 this.angle = Math.atan2( ty - sy, tx - sx );
 this.speed = 2;
 this.acceleration = 1.05;
 this.brightness = random( 50, 70 );
 // circle target indicator radius
 this.targetRadius = 1;
}

// update firework
Firework.prototype.update = function( index ) {
 // remove last item in coordinates array
 this.coordinates.pop();
 // add current coordinates to the start of the array
 this.coordinates.unshift( [ this.x, this.y ] );
 
 // cycle the circle target indicator radius
 if( this.targetRadius < 8 ) {
  this.targetRadius += 0.3;
 } else {
  this.targetRadius = 1;
 }
 
 // speed up the firework
 this.speed *= this.acceleration;
 
 // get the current velocities based on angle and speed
 var vx = Math.cos( this.angle ) * this.speed,
   vy = Math.sin( this.angle ) * this.speed;
 // how far will the firework have traveled with velocities applied?
 this.distanceTraveled = calculateDistance( this.sx, this.sy, this.x + vx, this.y + vy );
 
 // if the distance traveled, including velocities, is greater than the initial distance to the target, then the target has been reached
 if( this.distanceTraveled >= this.distanceToTarget ) {
  createParticles( this.tx, this.ty );
  // remove the firework, use the index passed into the update function to determine which to remove
  fireworks.splice( index, 1 );
 } else {
  // target not reached, keep traveling
  this.x += vx;
  this.y += vy;
 }
}

// draw firework
Firework.prototype.draw = function() {
 ctx.beginPath();
 // move to the last tracked coordinate in the set, then draw a line to the current x and y
 ctx.moveTo( this.coordinates[ this.coordinates.length - 1][ 0 ], this.coordinates[ this.coordinates.length - 1][ 1 ] );
 ctx.lineTo( this.x, this.y );
 ctx.strokeStyle = 'hsl(' + hue + ', 100%, ' + this.brightness + '%)';
 ctx.stroke();
 
 ctx.beginPath();
 // draw the target for this firework with a pulsing circle
 ctx.arc( this.tx, this.ty, this.targetRadius, 0, Math.PI * 2 );
 ctx.stroke();
}

// create particle
function Particle( x, y ) {
 this.x = x;
 this.y = y;
 // track the past coordinates of each particle to create a trail effect, increase the coordinate count to create more prominent trails
 this.coordinates = [];
 this.coordinateCount = 5;
 while( this.coordinateCount-- ) {
  this.coordinates.push( [ this.x, this.y ] );
 }
 // set a random angle in all possible directions, in radians
 this.angle = random( 0, Math.PI * 2 );
 this.speed = random( 1, 10 );
 // friction will slow the particle down
 this.friction = 0.95;
 // gravity will be applied and pull the particle down
 this.gravity = 1;
 // set the hue to a random number +-20 of the overall hue variable
 this.hue = random( hue - 20, hue + 20 );
 this.brightness = random( 50, 80 );
 this.alpha = 1;
 // set how fast the particle fades out
 this.decay = random( 0.015, 0.03 );
}

// update particle
Particle.prototype.update = function( index ) {
 // remove last item in coordinates array
 this.coordinates.pop();
 // add current coordinates to the start of the array
 this.coordinates.unshift( [ this.x, this.y ] );
 // slow down the particle
 this.speed *= this.friction;
 // apply velocity
 this.x += Math.cos( this.angle ) * this.speed;
 this.y += Math.sin( this.angle ) * this.speed + this.gravity;
 // fade out the particle
 this.alpha -= this.decay;
 
 // remove the particle once the alpha is low enough, based on the passed in index
 if( this.alpha <= this.decay ) {
  particles.splice( index, 1 );
 }
}

// draw particle
Particle.prototype.draw = function() {
 ctx. beginPath();
 // move to the last tracked coordinates in the set, then draw a line to the current x and y
 ctx.moveTo( this.coordinates[ this.coordinates.length - 1 ][ 0 ], this.coordinates[ this.coordinates.length - 1 ][ 1 ] );
 ctx.lineTo( this.x, this.y );
 ctx.strokeStyle = 'hsla(' + this.hue + ', 100%, ' + this.brightness + '%, ' + this.alpha + ')';
 ctx.stroke();
}

// create particle group/explosion
function createParticles( x, y ) {
 // increase the particle count for a bigger explosion, beware of the canvas performance hit with the increased particles though
 var particleCount = 30;
 while( particleCount-- ) {
  particles.push( new Particle( x, y ) );
 }
}

// main demo loop
function loop() {
 // this function will run endlessly with requestAnimationFrame
 requestAnimFrame( loop );
 
 // increase the hue to get different colored fireworks over time
 hue += 0.5;
 
 // normally, clearRect() would be used to clear the canvas
 // we want to create a trailing effect though
 // setting the composite operation to destination-out will allow us to clear the canvas at a specific opacity, rather than wiping it entirely
 ctx.globalCompositeOperation = 'destination-out';
 // decrease the alpha property to create more prominent trails
 ctx.fillStyle = 'rgba(0, 0, 0, 0.5)';
 ctx.fillRect( 0, 0, cw, ch );
 // change the composite operation back to our main mode
 // lighter creates bright highlight points as the fireworks and particles overlap each other
 ctx.globalCompositeOperation = 'lighter';
 
 // loop over each firework, draw it, update it
 var i = fireworks.length;
 while( i-- ) {
  fireworks[ i ].draw();
  fireworks[ i ].update( i );
 }
 
 // loop over each particle, draw it, update it
 var i = particles.length;
 while( i-- ) {
  particles[ i ].draw();
  particles[ i ].update( i );
 }
 
 // launch fireworks automatically to random coordinates, when the mouse isn't down
 if( timerTick >= timerTotal ) {
  if( !mousedown ) {
   // start the firework at the bottom middle of the screen, then set the random target coordinates, the random y coordinates will be set within the range of the top half of the screen
   fireworks.push( new Firework( cw / 2, ch, random( 0, cw ), random( 0, ch / 2 ) ) );
   timerTick = 0;
  }
 } else {
  timerTick++;
 }
 
 // limit the rate at which fireworks get launched when mouse is down
 if( limiterTick >= limiterTotal ) {
  if( mousedown ) {
   // start the firework at the bottom middle of the screen, then set the current mouse coordinates as the target
   fireworks.push( new Firework( cw / 2, ch, mx, my ) );
   limiterTick = 0;
  }
 } else {
  limiterTick++;
 }
}

// mouse event bindings
// update the mouse coordinates on mousemove
canvas.addEventListener( 'mousemove', function( e ) {
 mx = e.pageX - canvas.offsetLeft;
 my = e.pageY - canvas.offsetTop;
});

// toggle mousedown state and prevent canvas from being selected
canvas.addEventListener( 'mousedown', function( e ) {
 e.preventDefault();
 mousedown = true;
});

canvas.addEventListener( 'mouseup', function( e ) {
 e.preventDefault();
 mousedown = false;
});

// once the window loads, we are ready for some fireworks!
window.onload = loop;
//]]>
</script> 

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À, nếu bạn muốn giữ nền  blog của mình thì  xóa " background: #222 " đi nha hoặc cũng có thể chỉnh màu khác.

Thế là xong, với những bước đơn giản trên là Blog của bạn đã có không khí của mùa Xuân năm nay rồi, chúc các bạn thành công và nhớ share để giúp Blog nhé.