/** * Stylesheet.js: utility methods for scripting CSS stylesheets. *  * This module defines a Stylesheet class that is a simple wrapper * around an element of the document.styleSheets[] array.  It defines useful * cross-platform methods for querying and modifying the stylesheet. **/// Construct a new Stylesheet object that wraps the specified CSSStylesheet.// If ss is a number, look up the stylesheet in the styleSheet[] array.function Stylesheet(ss) {    if (typeof ss == "number") ss = document.styleSheets[ss];    this.ss = ss;}// Return the rules array for this stylesheet.Stylesheet.prototype.getRules = function() {    // Use the W3C property if defined; otherwise use the IE property    return this.ss.cssRules?this.ss.cssRules:this.ss.rules;}// Return a rule of the stylesheet.  If s is a number, we return the rule// at that index.  Otherwise, we assume s is a selector and look for a rule// that matches that selector.Stylesheet.prototype.getRule = function(s) {    var rules = this.getRules();    if (!rules) return null;    if (typeof s == "number") return rules[s];       // Assume s is a selector    // Loop backward through the rules so that if there is more than one    // rule that matches s, we find the one with the highest precedence.    s = s.toLowerCase();    for(var i = rules.length-1; i >= 0; i--) {        if (rules[i].selectorText.toLowerCase() == s) return rules[i];    }    return null;};// Return the CSS2Properties object for the specified rule.// Rules can be specified by number or by selectorStylesheet.prototype.getStyles = function(s) {    var rule = this.getRule(s);    if (rule && rule.style) return rule.style;    else return null;};// Return the style text for the specified rule.Stylesheet.prototype.getStyleText = function(s) {    var rule = this.getRule(s);    if (rule && rule.style && rule.style.cssText) return rule.style.cssText;    else return "";};// Insert a rule into the stylesheet.// The rule consists of the specified selector and style strings.// It is inserted at index n.  If n is omitted, it is appended to the end.Stylesheet.prototype.insertRule = function(selector, styles, n) {    if (n == undefined) {        var rules = this.getRules();        n = rules.length;    }    if (this.ss.insertRule)   // Try the W3C API first        this.ss.insertRule(selector + "{" + styles + "}", n);    else if (this.ss.addRule) // Otherwise use the IE API        this.ss.addRule(selector, styles, n);};// Remove the rule from the specified position in the stylesheet.// If s is a number, delete the rule at that position.// If s is a string, delete the rule with that selector.// If n is not specified, delete the last rule in the stylesheet.Stylesheet.prototype.deleteRule = function(s) {    // If s is undefined, make it the index of the last rule    if (s == undefined) {        var rules = this.getRules();        s = rules.length-1;    }    // If s is not a number, look for a matching rule and get its index    if (typeof s != "number") {        s = s.toLowerCase();    // convert to lowercase        var rules = this.getRules();        for(var i = rules.length-1; i >= 0; i--) {            if (rules[i].selectorText.toLowerCase() == s) {                s = i;  // Remember the index of the rule to delete                break;  // And stop searching            }        }        // If we didn't' find a match, just give up        if (i == -1) return;    }    // At this point s will be a number.    // Try the W3C API first, then try the IE API    if (this.ss.deleteRule) this.ss.deleteRule(s);    else if (this.ss.removeRule) this.ss.removeRule(s);};