这个太简单了。。是用javascript结合CSS实现。。
如果你懂这两样的话。。我就把大概的原理给你说一下。。
那个登录框先做好。。在页面设置它的DIV属性display是none，z-index值为99（不过百度可是没有这么做，在本身的页面没有这个，而是通过AJAX技术加载的），然后通过那个登陆链接点击后通过JS设置它的display属性为block,然后还创建一个DIV层它的z-index值为77（比99小就行了），它的宽设置为100％，高设置为100％，透明度设置为50％。。如果此就可以做到了。。
你把CSS中的这两行的background改下body{overflow:hiddenbackground:red}
html{overflow:hiddenbackground:red}
<!DOCTYPE html><!-- saved from url=http://keyup.cn -->
<html>
<head><meta http-equiv="Content-Type" content="text/html charset=UTF-8">
<meta content="width=device-width,height=device-height,inital-scale=1.0,maximum-scale=1.0,user-scalable=no" name="viewport">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<title>烟花</title>
<style type="text/css">
html,body{height:100%margin:0padding:0}
ul,li{text-indent:0text-decoration:nonemargin:0padding:0}
img{border:0}
body{background-color:#000color:#999font:100%/18px helvetica, arial, sans-serif}
canvas{cursor:crosshairdisplay:blockleft:0position:absolutetop:0z-index:20}
#header img{width:100% height:20%}
#bg img{width:100% height:80%}
#header,#bg{position:fixedleft:0right:0z-index:10}
#header{top:0}
#bg{position:fixedz-index:1}
audio{position:fixeddisplay:nonebottom:0left:0right:0width:100%z-index:5}
</style>
<link rel="shortcut icon" type="image/x-icon" href="">
<style type="text/css"></style><style id="style-1-cropbar-clipper">
.en-markup-crop-options {
top: 18px !important
left: 50% !important
margin-left: -100px !important
width: 200px !important
border: 2px rgba(255,255,255,.38) solid !important
border-radius: 4px !important
}
.en-markup-crop-options div div:first-of-type {
margin-left: 0px !important
}
#.bg {
background-color: black
}
</style>
</head>
<body>
<div id="bg"></div>
<script src="http://www.jq22.com/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript">
$(function(){
var Fireworks = function(){
var self = this
var rand = function(rMi, rMa){return ~~((Math.random()*(rMa-rMi+1))+rMi)}
var hitTest = function(x1, y1, w1, h1, x2, y2, w2, h2){return !(x1 + w1 < x2 || x2 + w2 < x1 || y1 + h1 < y2 || y2 + h2 < y1)}
window.requestAnimFrame=function(){return window.requestAnimationFrame||window.webkitRequestAnimationFrame||window.mozRequestAnimationFrame||window.oRequestAnimationFrame||window.msRequestAnimationFrame||function(a){window.setTimeout(a,1E3/60)}}()
self.init = function(){
self.canvas = document.createElement('canvas')
self.canvas.width = self.cw = $(window).innerWidth()
self.canvas.height = self.ch = $(window).innerHeight()
self.particles = []
self.partCount = 150
self.fireworks = []
self.mx = self.cw/2
self.my = self.ch/2
self.currentHue = 30
self.partSpeed = 5
self.partSpeedVariance = 10
self.partWind = 50
self.partFriction = 5
self.partGravity = 1
self.hueMin = 0
self.hueMax = 360
self.fworkSpeed = 4
self.fworkAccel = 10
self.hueVariance = 30
self.flickerDensity = 25
self.showShockwave = true
self.showTarget = false
self.clearAlpha = 25
$(document.body).append(self.canvas)
self.ctx = self.canvas.getContext('2d')
self.ctx.lineCap = 'round'
self.ctx.lineJoin = 'round'
self.lineWidth = 1
self.bindEvents()
self.canvasLoop()
self.canvas.onselectstart = function() {
return false
}
}
self.createParticles = function(x,y, hue){
var countdown = self.partCount
while(countdown--){
var newParticle = {
x: x,
y: y,
coordLast: [
{x: x, y: y},
{x: x, y: y},
{x: x, y: y}
],
angle: rand(0, 360),
speed: rand(((self.partSpeed - self.partSpeedVariance) <= 0) ? 1 : self.partSpeed - self.partSpeedVariance, (self.partSpeed + self.partSpeedVariance)),
friction: 1 - self.partFriction/100,
gravity: self.partGravity/2,
hue: rand(hue-self.hueVariance, hue+self.hueVariance),
brightness: rand(50, 80),
alpha: rand(40,100)/100,
decay: rand(10, 50)/1000,
wind: (rand(0, self.partWind) - (self.partWind/2))/25,
lineWidth: self.lineWidth
}
self.particles.push(newParticle)
}
}
self.updateParticles = function(){
var i = self.particles.length
while(i--){
var p = self.particles[i]
var radians = p.angle * Math.PI / 180
var vx = Math.cos(radians) * p.speed
var vy = Math.sin(radians) * p.speed
p.speed *= p.friction
p.coordLast[2].x = p.coordLast[1].x
p.coordLast[2].y = p.coordLast[1].y
p.coordLast[1].x = p.coordLast[0].x
p.coordLast[1].y = p.coordLast[0].y
p.coordLast[0].x = p.x
p.coordLast[0].y = p.y
p.x += vx
p.y += vy
p.y += p.gravity
p.angle += p.wind
p.alpha -= p.decay
if(!hitTest(0,0,self.cw,self.ch,p.x-p.radius, p.y-p.radius, p.radius*2, p.radius*2) || p.alpha < .05){
self.particles.splice(i, 1)
}
}
}
self.drawParticles = function(){
var i = self.particles.length
while(i--){
var p = self.particles[i]
var coordRand = (rand(1,3)-1)
self.ctx.beginPath()
self.ctx.moveTo(Math.round(p.coordLast[coordRand].x), Math.round(p.coordLast[coordRand].y))
self.ctx.lineTo(Math.round(p.x), Math.round(p.y))
self.ctx.closePath()
self.ctx.strokeStyle = 'hsla('+p.hue+', 100%, '+p.brightness+'%, '+p.alpha+')'
self.ctx.stroke()
if(self.flickerDensity > 0){
var inverseDensity = 50 - self.flickerDensity
if(rand(0, inverseDensity) === inverseDensity){
self.ctx.beginPath()
self.ctx.arc(Math.round(p.x), Math.round(p.y), rand(p.lineWidth,p.lineWidth+3)/2, 0, Math.PI*2, false)
self.ctx.closePath()
var randAlpha = rand(50,100)/100
self.ctx.fillStyle = 'hsla('+p.hue+', 100%, '+p.brightness+'%, '+randAlpha+')'
self.ctx.fill()
}
}
}
}
self.createFireworks = function(startX, startY, targetX, targetY){
var newFirework = {
x: startX,
y: startY,
startX: startX,
startY: startY,
hitX: false,
hitY: false,
coordLast: [
{x: startX, y: startY},
{x: startX, y: startY},
{x: startX, y: startY}
],
targetX: targetX,
targetY: targetY,
speed: self.fworkSpeed,
angle: Math.atan2(targetY - startY, targetX - startX),
shockwaveAngle: Math.atan2(targetY - startY, targetX - startX)+(90*(Math.PI/180)),
acceleration: self.fworkAccel/100,
hue: self.currentHue,
brightness: rand(50, 80),
alpha: rand(50,100)/100,
lineWidth: self.lineWidth
}
self.fireworks.push(newFirework)
}
self.updateFireworks = function(){
var i = self.fireworks.length
while(i--){
var f = self.fireworks[i]
self.ctx.lineWidth = f.lineWidth
vx = Math.cos(f.angle) * f.speed,
vy = Math.sin(f.angle) * f.speed
f.speed *= 1 + f.acceleration
f.coordLast[2].x = f.coordLast[1].x
f.coordLast[2].y = f.coordLast[1].y
f.coordLast[1].x = f.coordLast[0].x
f.coordLast[1].y = f.coordLast[0].y
f.coordLast[0].x = f.x
f.coordLast[0].y = f.y
if(f.startX >= f.targetX){
if(f.x + vx <= f.targetX){
f.x = f.targetX
f.hitX = true
} else {
f.x += vx
}
} else {
if(f.x + vx >= f.targetX){
f.x = f.targetX
f.hitX = true
} else {
f.x += vx
}
}
if(f.startY >= f.targetY){
if(f.y + vy <= f.targetY){
f.y = f.targetY
f.hitY = true
} else {
f.y += vy
}
} else {
if(f.y + vy >= f.targetY){
f.y = f.targetY
f.hitY = true
} else {
f.y += vy
}
}
if(f.hitX && f.hitY){
self.createParticles(f.targetX, f.targetY, f.hue)
self.fireworks.splice(i, 1)
}
}
}
self.drawFireworks = function(){
var i = self.fireworks.length
self.ctx.globalCompositeOperation = 'lighter'
while(i--){
var f = self.fireworks[i]
self.ctx.lineWidth = f.lineWidth
var coordRand = (rand(1,3)-1)
self.ctx.beginPath()
self.ctx.moveTo(Math.round(f.coordLast[coordRand].x), Math.round(f.coordLast[coordRand].y))
self.ctx.lineTo(Math.round(f.x), Math.round(f.y))
self.ctx.closePath()
self.ctx.strokeStyle = 'hsla('+f.hue+', 100%, '+f.brightness+'%, '+f.alpha+')'
self.ctx.stroke()
if(self.showTarget){
self.ctx.save()
self.ctx.beginPath()
self.ctx.arc(Math.round(f.targetX), Math.round(f.targetY), rand(1,8), 0, Math.PI*2, false)
self.ctx.closePath()
self.ctx.lineWidth = 1
self.ctx.stroke()
self.ctx.restore()
}
if(self.showShockwave){
self.ctx.save()
self.ctx.translate(Math.round(f.x), Math.round(f.y))
self.ctx.rotate(f.shockwaveAngle)
self.ctx.beginPath()
self.ctx.arc(0, 0, 1*(f.speed/5), 0, Math.PI, true)
self.ctx.strokeStyle = 'hsla('+f.hue+', 100%, '+f.brightness+'%, '+rand(25, 60)/100+')'
self.ctx.lineWidth = f.lineWidth
self.ctx.stroke()
self.ctx.restore()
}
}
}
self.bindEvents = function(){
$(window).on('resize', function(){
clearTimeout(self.timeout)
self.timeout = setTimeout(function() {
self.canvas.width = self.cw = $(window).innerWidth()
self.canvas.height = self.ch = $(window).innerHeight()
self.ctx.lineCap = 'round'
self.ctx.lineJoin = 'round'
}, 100)
})
$(self.canvas).on('mousedown', function(e){
self.mx = e.pageX - self.canvas.offsetLeft
self.my = e.pageY - self.canvas.offsetTop
self.currentHue = rand(self.hueMin, self.hueMax)
self.createFireworks(self.cw/2, self.ch, self.mx, self.my)
$(self.canvas).on('mousemove.fireworks', function(e){
self.mx = e.pageX - self.canvas.offsetLeft
self.my = e.pageY - self.canvas.offsetTop
self.currentHue = rand(self.hueMin, self.hueMax)
self.createFireworks(self.cw/2, self.ch, self.mx, self.my)
})
})
$(self.canvas).on('mouseup', function(e){
$(self.canvas).off('mousemove.fireworks')
})
}
self.clear = function(){
self.particles = []
self.fireworks = []
self.ctx.clearRect(0, 0, self.cw, self.ch)
}
self.canvasLoop = function(){
requestAnimFrame(self.canvasLoop, self.canvas)
self.ctx.globalCompositeOperation = 'destination-out'
self.ctx.fillStyle = 'rgba(0,0,0,'+self.clearAlpha/100+')'
self.ctx.fillRect(0,0,self.cw,self.ch)
self.updateFireworks()
self.updateParticles()
self.drawFireworks()
self.drawParticles()
}
self.init()
}
var fworks = new Fireworks()
})
</script>
<script type="text/javascript">
$(document).ready(function() {
setTimeout(function() {
$("#header").hide("slow")
},2000)
})
</script>
</body>
</html>
