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Code #1 Tạo tuyết rơi hạt to cho Blogspot

<!-- Tuyet -->
<style>
#snowflakeContainer {
    position: absolute;
    left: 0px;
    top: 0px;
}
.snowflake {
    padding-left: 15px;
    font-family: Cambria, Georgia, serif;
    font-size: 14px;
    line-height: 24px;
    position: fixed;
    color: #FFFFFF;
    user-select: none;
    z-index: 1000;
}
.snowflake:hover {
    cursor: default;
}
  </style>
<div id='snowflakeContainer'>
<p class='snowflake'>*</p>
</div>
<script>// The star of every good animation
var requestAnimationFrame = window.requestAnimationFrame ||
                            window.mozRequestAnimationFrame ||
                            window.webkitRequestAnimationFrame ||
                            window.msRequestAnimationFrame;
var transforms = ["transform",
                  "msTransform",
                  "webkitTransform",
                  "mozTransform",
                  "oTransform"];
                 
var transformProperty = getSupportedPropertyName(transforms);
// Array to store our Snowflake objects
var snowflakes = [];
// Global variables to store our browser's window size
var browserWidth;
var browserHeight;
// Specify the number of snowflakes you want visible
var numberOfSnowflakes = 50;
// Flag to reset the position of the snowflakes
var resetPosition = false;
//
// It all starts here...
//
function setup() {
    window.addEventListener("DOMContentLoaded", generateSnowflakes, false);
    window.addEventListener("resize", setResetFlag, false);
}
setup();
//
// Vendor prefix management
//
function getSupportedPropertyName(properties) {
    for (var i = 0; i < properties.length; i++) {
        if (typeof document.body.style[properties[i]] != "undefined") {
            return properties[i];
        }
    }
    return null;
}
//
// Constructor for our Snowflake object
//
function Snowflake(element, radius, speed, xPos, yPos) {
    // set initial snowflake properties
    this.element = element;
    this.radius = radius;
    this.speed = speed;
    this.xPos = xPos;
    this.yPos = yPos;
 
    // declare variables used for snowflake's motion
    this.counter = 0;
    this.sign = Math.random() < 0.5 ? 1 : -1;
 
    // setting an initial opacity and size for our snowflake
    this.element.style.opacity = .1 + Math.random();
    this.element.style.fontSize = 12 + Math.random() * 50 + "px";
}
//
// The function responsible for actually moving our snowflake
//
Snowflake.prototype.update = function () {
    // using some trigonometry to determine our x and y position
    this.counter += this.speed / 5000;
    this.xPos += this.sign * this.speed * Math.cos(this.counter) / 40;
    this.yPos += Math.sin(this.counter) / 40 + this.speed / 30;
    // setting our snowflake's position
    setTranslate3DTransform(this.element, Math.round(this.xPos), Math.round(this.yPos));
 
    // if snowflake goes below the browser window, move it back to the top
    if (this.yPos > browserHeight) {
        this.yPos = -50;
    }
}
//
// A performant way to set your snowflake's position
//
function setTranslate3DTransform(element, xPosition, yPosition) {
    var val = "translate3d(" + xPosition + "px, " + yPosition + "px" + ", 0)";
    element.style[transformProperty] = val;
}
//
// The function responsible for creating the snowflake
//
function generateSnowflakes() {
 
    // get our snowflake element from the DOM and store it
    var originalSnowflake = document.querySelector(".snowflake");
 
    // access our snowflake element's parent container
    var snowflakeContainer = originalSnowflake.parentNode;
 
    // get our browser's size
    browserWidth = document.documentElement.clientWidth;
    browserHeight = document.documentElement.clientHeight;
         
    // create each individual snowflake
    for (var i = 0; i < numberOfSnowflakes; i++) {
 
        // clone our original snowflake and add it to snowflakeContainer
        var snowflakeCopy = originalSnowflake.cloneNode(true);
        snowflakeContainer.appendChild(snowflakeCopy);
        // set our snowflake's initial position and related properties
        var initialXPos = getPosition(50, browserWidth);
        var initialYPos = getPosition(50, browserHeight);
        var speed = 5+Math.random()*40;
        var radius = 4+Math.random()*10;
     
        // create our Snowflake object
        var snowflakeObject = new Snowflake(snowflakeCopy,
                                            radius,
                                            speed,
                                            initialXPos,
                                            initialYPos);
        snowflakes.push(snowflakeObject);
    }
 
    // remove the original snowflake because we no longer need it visible
    snowflakeContainer.removeChild(originalSnowflake);
 
    // call the moveSnowflakes function every 30 milliseconds
    moveSnowflakes();
}
//
// Responsible for moving each snowflake by calling its update function
//
function moveSnowflakes() {
    for (var i = 0; i < snowflakes.length; i++) {
        var snowflake = snowflakes[i];
        snowflake.update();
    }
 
    // Reset the position of all the snowflakes to a new value
    if (resetPosition) {
        browserWidth = document.documentElement.clientWidth;
        browserHeight = document.documentElement.clientHeight;
     
        for (var i = 0; i < snowflakes.length; i++) {
            var snowflake = snowflakes[i];
         
            snowflake.xPos = getPosition(50, browserWidth);
            snowflake.yPos = getPosition(50, browserHeight);
        }
     
        resetPosition = false;
    }
 
    requestAnimationFrame(moveSnowflakes);
}
//
// This function returns a number between (maximum - offset) and (maximum + offset)
//
function getPosition(offset, size) {
    return Math.round(-1*offset + Math.random() * (size+2*offset));
}
//
// Trigger a reset of all the snowflakes' positions
//
function setResetFlag(e) {
    resetPosition = true;
}</script>

Code 2: Tạo tuyết rơi hạt nhỏ cho blogspot