Hi nedash,
Please refer below sample.
CSS
@font-face {
    font-family: 'Mj_Dinar Two Light'; /*تعریف یک نام برای فونت*/
    src: url('../fonts/Mj_Dinar Two Light.eot'); /*اکسپلورر 9 به بعد*/
    src: local('Mj_Dinar Two Light'), /*بررسی نصب بودن فونت در سیستم کاربر*/
    local('Mj_Dinar Two Light'), /*برای برخی از مرورگرها مانند سافاری*/
    url('../fonts/Mj_Dinar Two Light.eot?#iefix') format('embedded-opentype'), /*هک برای اکسپلورر 8 و ماقبل*/
    url('../fonts/Mj_Dinar Two Light.woff') format('woff'), /*مرورگر های جدید*/
    url('../fonts/Mj_Dinar Two Light.ttf') format('truetype'), /*تمام مرورگرها به جزء اکسپلورر*/
    url('../fonts/Mj_Dinar Two Light.svg#Mj_Dinar Two Light') format('svg'); /*نسخه های قدیمی سیستم عامل iOS*/
    font-style: normal;
    font-weight: normal;
}
@font-face {
    font-family: 'IRANSans-Medium-web'; /*تعریف یک نام برای فونت*/
    src: url('../fonts/IRANSans-Medium-web.eot'); /*اکسپلورر 9 به بعد*/
    src: local('IRANSans-Medium-web'), /*بررسی نصب بودن فونت در سیستم کاربر*/
    local('IRANSans-Medium-web'), /*برای برخی از مرورگرها مانند سافاری*/
    url('../fonts/IRANSans-Medium-web.eot?#iefix') format('embedded-opentype'), /*هک برای اکسپلورر 8 و ماقبل*/
    url('../fonts/IRANSans-Medium-web.woff') format('woff'), /*مرورگر های جدید*/
    url('../fonts/IRANSans-Medium-web.ttf') format('truetype'), /*تمام مرورگرها به جزء اکسپلورر*/
    url('../fonts/IRANSans-Medium-web.svg#IRANSans-Medium-web') format('svg'); /*نسخه های قدیمی سیستم عامل iOS*/
    font-style: normal;
    font-weight: normal;
}
.selectric-wrapper {
    position: relative;
    cursor: pointer;
    direction: rtl;
}
.selectric-responsive {
    width: 100%;
    direction: rtl;
}
.selectric {
    border-radius: 0px;
    background: #1B1B1B;
    position: relative;
    border: 1px solid #D40000; /*رنگ ddl*/
    direction: rtl;
    height: 38px;
}
    .selectric .label {
        display: block;
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
        margin: 0 28px 0 10px;
        font-size: 16px;
        line-height: 28px;
        color: white; /*رنگ فونت خود dropdown*/
        height: 28px; /*طول dropdown*/
        text-align: right;
        direction: rtl;
        font-family: IRANSans-Medium-web;
        padding-top: 5px; /*تنظیم فاصله "همه" از بالا*/
        padding-right: 5px;
    }
    .selectric .button {
        display: block;
        position: absolute;
        right: 0;
        top: 0;
        width: 22px;
        height: 36px; /*تعیین طول فلش*/
        /*color:red;*/
        text-align: center;
        font: 0/0 a;
        *font: 20px/38px Lucida Sans Unicode, Arial Unicode MS, Arial;
        border: 1px solid #6d6b5c;
        direction: rtl;
        background: #2c2a1e; /*تعیین رنگ پشت فلش*/
    }
        .selectric .button:after {
            content: " ";
            position: absolute;
            top: 0;
            right: 0;
            bottom: 0;
            left: 0;
            margin: auto;
            width: 0;
            height: 0;
            border: 4px solid transparent;
            border-top-color: #6d6b5c; /**********تعیین رنگ فلش**/
            border-bottom: none;
            direction: rtl;
        }
.selectric-hover .selectric {
    background: #2c2a1e;
    direction: rtl;
}
    .selectric-hover .selectric .button {
        color: #e6e6e6;
    }
        /**رنگ فلش وقتی با موس روی آن میرویم**/
        .selectric-hover .selectric .button:after {
            border-top-color: #c8ba61;
        }
.selectric-open {
    z-index: 9999;
}
    .selectric-open .selectric-items {
        display: block;
    }
.selectric-disabled {
    filter: alpha(opacity=50);
    opacity: 0.5;
    cursor: default;
    user-select: none;
}
.selectric-hide-select {
    position: relative;
    overflow: hidden;
    width: 0;
    height: 0;
}
    .selectric-hide-select select {
        position: absolute;
        left: -100%;
        display: none;
        direction: rtl;
    }
.selectric-input {
    position: absolute !important;
    top: 0 !important;
    left: 0 !important;
    overflow: hidden !important;
    clip: rect(0, 0, 0, 0) !important;
    margin: 0 !important;
    padding: 0 !important;
    width: 1px !important;
    height: 1px !important;
    outline: none !important;
    border: none !important;
    *font: 0/0 a !important;
    background: none !important;
    direction: rtl;
}
.selectric-temp-show {
    position: absolute !important;
    visibility: hidden !important;
    display: block !important;
    direction: rtl;
}
/* Items box */
.selectric-items {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    font-family: IRANSans-Medium-web;
    background: #1b1b1b; /*رنگ پشت زمینه آیتم ها*/
    border: 1px solid #d40000; /**کادر دور موارد dropdown**/
    z-index: -1;
    box-shadow: 0 0 10px -6px;
    text-align: right;
    direction: rtl;
}
    .selectric-items .selectric-scroll {
        height: 100%;
        overflow: auto;
        direction: ltr;
    }
.selectric-above .selectric-items {
    top: auto;
    bottom: 100%;
    direction: rtl;
}
.selectric-items ul, .selectric-items li {
    list-style: none;
    padding: 0;
    margin: 0;
    font-size: 14px;
    line-height: 20px; /*طول کادر آیتم*/
    min-height: 20px;
    direction: rtl;
}
.selectric-items li {
    display: block;
    padding: 8px;
    /*border-top: 1px solid orange;
  border-bottom: 1px solid orange;*/ /*رنگ بردر بالا و پایین بردرها*/
    color: white; /*رنگ فونت*/
    cursor: pointer;
    direction: rtl;
    /*background:red;*/
}
    .selectric-items li.selected {
        background: #550300; /*رنگ آیتم انتخاب شده*/
        color: #d4cd6d; /*رنگ فونت آیتم انتخابی*/
    }
    .selectric-items li:hover {
        background: #3a3a3a;
        color: white;
        direction: rtl;
    }
.selectric-items .disabled {
    filter: alpha(opacity=50);
    opacity: 0.5;
    cursor: default !important;
    background: none !important;
    color: #666 !important;
    user-select: none;
    direction: rtl;
}
.selectric-items .selectric-group .selectric-group-label {
    font-weight: bold;
    padding-left: 10px;
    cursor: default;
    user-select: none;
    background: none;
    color: #444;
    direction: rtl;
}
.selectric-items .selectric-group.disabled li {
    filter: alpha(opacity=100);
    opacity: 1;
    direction: rtl;
}
.selectric-items .selectric-group li {
    padding-left: 25px;
    direction: rtl;
}
.selectric {
    border-radius: 0px;
    background: #1B1B1B;
    position: relative;
    border: 1px solid #D40000; /*رنگ ddl*/
    direction: rtl;
    height: 38px;
}
HTML
<link href="Selectric.css" rel="stylesheet" />
<style type="text/css">
    .Dlnama {
        border: 1px solid red !important;
        background: none;
    }
    .Dlkaf {
        border: 1px solid blue !important;
        background: none;
    }
</style>
<div id="JkafL">
    <asp:DropDownList ID="Ddlnama" runat="server" CssClass="selectric Dlnama">
        <asp:ListItem>--Select--</asp:ListItem>
        <asp:ListItem>Aspsnippets</asp:ListItem>
        <asp:ListItem>Aspforums</asp:ListItem>
    </asp:DropDownList>
</div>
<hr />
<div id="JkafR">
    <asp:DropDownList ID="Ddlkaf" runat="server" CssClass="selectric Dlkaf">
        <asp:ListItem>--Select--</asp:ListItem>
        <asp:ListItem>Aspsnippets</asp:ListItem>
        <asp:ListItem>Aspforums</asp:ListItem>
    </asp:DropDownList>
</div>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
    !function (e) {
        "function" == typeof define && define.amd ? define(["jquery"], e) : "object" == typeof module && module.exports ? module.exports = function (t, s) {
            return void 0 === s && (s = "undefined" != typeof window ? require("jquery") : require("jquery")(t)), e(s), s
        }
            : e(jQuery)
    }
        (function (e) {
            "use strict";
            var t = e(document), s = e(window), i = "selectric", l = ".sl", n = ["a", "e", "i", "o", "u", "n", "c", "y"], o = [/[\xE0-\xE5]/g, /[\xE8-\xEB]/g, /[\xEC-\xEF]/g, /[\xF2-\xF6]/g, /[\xF9-\xFC]/g, /[\xF1]/g, /[\xE7]/g, /[\xFD-\xFF]/g], a = function (t, s) {
                var i = this;
                i.element = t, i.$element = e(t), i.state = {
                    enabled: !1, opened: !1, currValue: -1, selectedIdx: -1
                }
                    , i.eventTriggers = {
                        open: i.open, close: i.close, destroy: i.destroy, refresh: i.refresh, init: i.init
                    }
                    , i.init(s)
            }
                ;
            a.prototype = {
                utils: {
                    isMobile: function () {
                        return /android|ip(hone|od|ad)/i.test(navigator.userAgent)
                    }
                    , escapeRegExp: function (e) {
                        return e.replace(/[.*+?^${
        }
                        () | [\]\\]/ g, "\\$&")
    }
    , replaceDiacritics: function (e) {
        for (var t = o.length;
            t--;
        ) e = e.toLowerCase().replace(o[t], n[t]);
        return e
    }
    , format: function (e) {
        var t = arguments;
        return ("" + e).replace(/\{
            (?: (\d +) | (\w +)) \
    }
    /g, function (e, s, i) {
    return i && t[1] ? t[1][i] : t[s]
        }
        )
    }
    , nextEnabledItem: function (e, t) {
        for (;
            e[t = (t + 1) % e.length].disabled;
        );
        return t
    }
    , previousEnabledItem: function (e, t) {
        for (;
            e[t = (t > 0 ? t : e.length) - 1].disabled;
        );
        return t
    }
    , toDash: function (e) {
        return e.replace(/([a-z])([A-Z])/g, "$1-$2").toLowerCase()
    }
    , triggerCallback: function (t, s) {
        var l = s.element, n = s.options["on" + t];
        e.isFunction(n) && n.call(l, l, s), e.fn[i].hooks[t] && e.each(e.fn[i].hooks[t], function () {
            this.call(l, l, s)
        }
        ), e(l).trigger(i + "-" + this.toDash(t), s)
    }
}
, init: function (t) {
        var s = this;
        if (s.options = e.extend(!0, {
        }
            , e.fn[i].defaults, s.options, t), s.utils.triggerCallback("BeforeInit", s), s.destroy(!0), s.options.disableOnMobile && s.utils.isMobile()) s.disableOnMobile = !0;
        else {
            s.classes = s.getClassNames();
            var l = e("<input/>", {
                class: s.classes.input, readonly: s.utils.isMobile()
            }
            ), n = e("<div/>", {
                class: s.classes.items, tabindex: -1
            }
            ), o = e("<div/>", {
                class: s.classes.scroll
            }
            ), a = e("<div/>", {
                class: s.classes.prefix, html: s.options.arrowButtonMarkup
            }
            ), r = e("<span/>", {
                class: "label"
            }
            ), p = s.$element.wrap("<div/>").parent().append(a.prepend(r), n, l);
            s.elements = {
                input: l, items: n, itemsScroll: o, wrapper: a, label: r, outerWrapper: p
            }
                , s.$element.on(s.eventTriggers).wrap('<div class="' + s.classes.hideselect + '"/>'), s.originalTabindex = s.$element.prop("tabindex"), s.$element.prop("tabindex", !1), s.populate(), s.activate(), s.utils.triggerCallback("Init", s)
        }
    }
, activate: function () {
        var e = this, t = e.$element.width();
        e.utils.triggerCallback("BeforeActivate", e), e.elements.outerWrapper.prop("class", [e.classes.wrapper, e.$element.prop("class").replace(/\S+/g, e.classes.prefix + "-$&"), e.options.responsive ? e.classes.responsive : ""].join(" ")), e.options.inheritOriginalWidth && t > 0 && e.elements.outerWrapper.width(t), e.$element.prop("disabled") ? (e.elements.outerWrapper.addClass(e.classes.disabled), e.elements.input.prop("disabled", !0)) : (e.state.enabled = !0, e.elements.outerWrapper.removeClass(e.classes.disabled), e.$li = e.elements.items.removeAttr("style").find("li"), e.bindEvents()), e.utils.triggerCallback("Activate", e)
    }
, getClassNames: function () {
        var t = this, s = t.options.customClass, i = {
        }
            ;
        return e.each("Input Items Open Disabled TempShow HideSelect Wrapper Focus Hover Responsive Above Scroll Group GroupLabel".split(" "), function (e, l) {
            var n = s.prefix + l;
            i[l.toLowerCase()] = s.camelCase ? n : t.utils.toDash(n)
        }
        ), i.prefix = s.prefix, i
    }
, setLabel: function () {
        var t = this, s = t.options.labelBuilder, i = t.lookupItems[t.state.currValue];
        t.elements.label.html(e.isFunction(s) ? s(i) : t.utils.format(s, i))
    }
, populate: function () {
        var t = this, s = t.$element.children(), i = t.$element.find("option"), l = i.index(i.filter(":selected")), n = 0;
        t.state.currValue = t.state.selected = ~l ? l : 0, t.state.selectedIdx = t.state.currValue, t.items = [], t.lookupItems = [], s.length && (s.each(function (s) {
            var i = e(this);
            if (i.is("optgroup")) {
                var l = {
                    element: i, label: i.prop("label"), groupDisabled: i.prop("disabled"), items: []
                }
                    ;
                i.children().each(function (s) {
                    var i = e(this), o = i.html();
                    l.items[s] = {
                        index: n, element: i, value: i.val(), text: o, slug: t.utils.replaceDiacritics(o), disabled: l.groupDisabled
                    }
                        , t.lookupItems[n] = l.items[s], n++
                }
                ), t.items[s] = l
            }
            else {
                var o = i.html();
                t.items[s] = {
                    index: n, element: i, value: i.val(), text: o, slug: t.utils.replaceDiacritics(o), disabled: i.prop("disabled")
                }
                    , t.lookupItems[n] = t.items[s], n++
            }
        }
        ), t.setLabel(), t.elements.items.append(t.elements.itemsScroll.html(t.getItemsMarkup(t.items))))
    }
, getItemsMarkup: function (t) {
        var s = this, i = "<ul>";
        return e.each(t, function (t, l) {
            void 0 !== l.label ? (i += s.utils.format('<ul class="{
            1
        }
        "><li class="{
            2
        }
        ">{
            3
        }
        </li > ', e.trim([s.classes.group, l.groupDisabled ? "disabled" : "", l.element.prop("class")].join(" ")), s.classes.grouplabel, l.element.prop("label")), e.each(l.items, function (e, t) {
    i += s.getItemMarkup(t.index, t)
        }
        ), i += "</ul>") : i += s.getItemMarkup(l.index, l)
    }
    ), i + "</ul>"
}
, getItemMarkup: function (t, s) {
        var i = this, l = i.options.optionsItemBuilder;
        return i.utils.format('<li data-index="{
        1
    }
    " class="{
        2
    }
    ">{
    3
    }
    </li > ', t, e.trim([t === i.state.currValue ? "selected" : "", t === i.items.length - 1 ? "last" : "", s.disabled ? "disabled" : ""].join(" ")), e.isFunction(l) ? l(s, s.element, t) : i.utils.format(l, s))
}
, bindEvents: function () {
        var t = this;
        t.elements.wrapper.add(t.$element).add(t.elements.outerWrapper).add(t.elements.input).off(l), t.elements.outerWrapper.on("mouseenter.sl mouseleave" + l, function (s) {
            e(this).toggleClass(t.classes.hover, "mouseenter" === s.type), t.options.openOnHover && (clearTimeout(t.closeTimer), "mouseleave" === s.type ? t.closeTimer = setTimeout(e.proxy(t.close, t), t.options.hoverIntentTimeout) : t.open())
        }
        ), t.elements.wrapper.on("click" + l, function (e) {
            t.state.opened ? t.close() : t.open(e)
        }
        ), t.elements.input.prop({
            tabindex: t.originalTabindex, disabled: !1
        }
        ).on("keydown" + l, e.proxy(t.handleKeys, t)).on("focusin" + l, function (e) {
            t.elements.outerWrapper.addClass(t.classes.focus), t.elements.input.one("blur", function () {
                t.elements.input.blur()
            }
            ), t.options.openOnFocus && !t.state.opened && t.open(e)
        }
        ).on("focusout" + l, function () {
            t.elements.outerWrapper.removeClass(t.classes.focus)
        }
        ).on("input propertychange", function () {
            var s = t.elements.input.val();
            clearTimeout(t.resetStr), t.resetStr = setTimeout(function () {
                t.elements.input.val("")
            }
                , t.options.keySearchTimeout), s.length && e.each(t.items, function (e, i) {
                    if (RegExp("^" + t.utils.escapeRegExp(s), "i").test(i.slug) && !i.disabled) return t.select(e), !1
                }
                )
        }
        ), t.$li.on({
            mousedown: function (e) {
                e.preventDefault(), e.stopPropagation()
            }
            , click: function () {
                return t.select(e(this).data("index"), !0), !1
            }
        }
        )
    }
, handleKeys: function (t) {
        var s = this, i = t.keyCode || t.which, l = s.options.keys, n = e.inArray(i, l.previous) > -1, o = e.inArray(i, l.next) > -1, a = e.inArray(i, l.select) > -1, r = e.inArray(i, l.open) > -1, p = s.state.selectedIdx, u = n && 0 === p || o && p + 1 === s.items.length, c = 0;
        if (13 !== i && 32 !== i || t.preventDefault(), n || o) {
            if (!s.options.allowWrap && u) return;
            n && (c = s.utils.previousEnabledItem(s.items, p)), o && (c = s.utils.nextEnabledItem(s.items, p)), s.select(c)
        }
        return a && s.state.opened ? void s.select(p, !0) : void (r && !s.state.opened && s.open())
    }
, refresh: function () {
        var e = this;
        e.populate(), e.activate(), e.utils.triggerCallback("Refresh", e)
    }
, setOptionsDimensions: function () {
        var e = this, t = e.elements.items.closest(":visible").children(":hidden").addClass(e.classes.tempshow), s = e.options.maxHeight, i = e.elements.items.outerWidth(), l = e.elements.wrapper.outerWidth() - (i - e.elements.items.width());
        !e.options.expandToItemText || l > i ? e.finalWidth = l : (e.elements.items.css("overflow", "scroll"), e.elements.outerWrapper.width(9e4), e.finalWidth = e.elements.items.width(), e.elements.items.css("overflow", ""), e.elements.outerWrapper.width("")), e.elements.items.width(e.finalWidth).height() > s && e.elements.items.height(s), t.removeClass(e.classes.tempshow)
    }
, isInViewport: function () {
        var e = this, t = s.scrollTop(), i = s.height(), l = e.elements.outerWrapper.offset().top, n = l + e.elements.outerWrapper.outerHeight() + e.itemsHeight <= t + i, o = l - e.itemsHeight > t, a = !n && o;
        e.elements.outerWrapper.toggleClass(e.classes.above, a)
    }
, detectItemVisibility: function (e) {
        var t = this, s = t.$li.eq(e).outerHeight(), i = t.$li[e].offsetTop, l = t.elements.itemsScroll.scrollTop(), n = i + 2 * s;
        t.elements.itemsScroll.scrollTop(n > l + t.itemsHeight ? n - t.itemsHeight : i - s < l ? i - s : l)
    }
, open: function (s) {
        var n = this;
        n.utils.triggerCallback("BeforeOpen", n), s && (s.preventDefault(), s.stopPropagation()), n.state.enabled && (n.setOptionsDimensions(), e("." + n.classes.hideselect, "." + n.classes.open).children()[i]("close"), n.state.opened = !0, n.itemsHeight = n.elements.items.outerHeight(), n.itemsInnerHeight = n.elements.items.height(), n.elements.outerWrapper.addClass(n.classes.open), n.elements.input.val(""), s && "focusin" !== s.type && n.elements.input.focus(), t.on("click" + l, e.proxy(n.close, n)).on("scroll" + l, e.proxy(n.isInViewport, n)), n.isInViewport(), n.options.preventWindowScroll && t.on("mousewheel.sl DOMMouseScroll" + l, "." + n.classes.scroll, function (t) {
            var s = t.originalEvent, i = e(this).scrollTop(), l = 0;
            "detail" in s && (l = -1 * s.detail), "wheelDelta" in s && (l = s.wheelDelta), "wheelDeltaY" in s && (l = s.wheelDeltaY), "deltaY" in s && (l = -1 * s.deltaY), (i === this.scrollHeight - n.itemsInnerHeight && l < 0 || 0 === i && l > 0) && t.preventDefault()
        }
        ), n.detectItemVisibility(n.state.selectedIdx), n.utils.triggerCallback("Open", n))
    }
, close: function () {
        var e = this;
        e.utils.triggerCallback("BeforeClose", e), e.change(), t.off(l), e.elements.outerWrapper.removeClass(e.classes.open), e.state.opened = !1, e.utils.triggerCallback("Close", e)
    }
, change: function () {
        var e = this;
        e.utils.triggerCallback("BeforeChange", e), e.state.currValue !== e.state.selectedIdx && (e.$element.prop("selectedIndex", e.state.currValue = e.state.selectedIdx).data("value", e.lookupItems[e.state.selectedIdx].text), e.setLabel()), e.utils.triggerCallback("Change", e)
    }
, select: function (e, t) {
        var s = this;
        void 0 !== e && (s.lookupItems[e].disabled || (s.$li.filter("[data-index]").removeClass("selected").eq(s.state.selectedIdx = e).addClass("selected"), s.detectItemVisibility(e), t && s.close()))
    }
, destroy: function (e) {
        var t = this;
        t.state && t.state.enabled && (t.elements.items.add(t.elements.wrapper).add(t.elements.input).remove(), e || t.$element.removeData(i).removeData("value"), t.$element.prop("tabindex", t.originalTabindex).off(l).off(t.eventTriggers).unwrap().unwrap(), t.state.enabled = !1)
    }
}
, e.fn[i] = function (t) {
        return this.each(function () {
            var s = e.data(this, i);
            s && !s.disableOnMobile ? "string" == typeof t && s[t] ? s[t]() : s.init(t) : e.data(this, i, new a(this, t))
        }
        )
    }
        , e.fn[i].hooks = {
            add: function (e, t, s) {
                this[e] || (this[e] = {
                }
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Screenshot
