目的

>使文本是唯一淡入淡出的东西,而持有文本的容器具有固定的高度以消除文本跳跃的外观
>删除scripts.js中的所有代码重复,尤其是所有let语句

Codepen：http://codepen.io/onlyandrewn/pen/NbdGrg

问题

我有一系列面板,按下btn按钮 – 上一个或btn – 接下来你会看到系列中的下一个面板.panel – one,.panel – two,旧的淡出淡出新的但是,当文本中的淡入淡出元素出现跳跃时.

scripts.js中

// Complete
function completeStepOne() {
    $(".circle--one").removeClass("is-selected");
    $(".check--one").removeClass("is-hidden");
    $(".text--one").addClass("is-strikethrough");
    $(".circle--one").addClass("is-completed");
    $(".number--one").addClass("is-hidden");
    $(".circle--two").addClass("is-selected");
    $(".text--two").removeClass("is-grey");
}

function completeStepTwo() {
    $(".circle--two").removeClass("is-selected");
    $(".check--two").removeClass("is-hidden");
    $(".text--two").addClass("is-strikethrough");
    $(".circle--two").addClass("is-completed");
    $(".number--two").addClass("is-hidden");
    $(".circle--three").addClass("is-selected");
    $(".text--three").removeClass("is-grey");
}

function completeStepsOneTwo() {
    $(".circle--one, .circle--two").removeClass("is-selected");
    $(".check--one, .check--two").removeClass("is-hidden");
    $(".text--one, .text--two").addClass("is-strikethrough");
    $(".circle--one, .circle--two").addClass("is-completed");
    $(".number--one, .number--two").addClass("is-hidden");
    $(".circle--three").addClass("is-selected");
    $(".text--three").removeClass("is-grey");
}

// Incomplete
function incompleteStepTwo() {
    $(".number--one").removeClass("is-hidden");
    $(".circle--one").addClass("is-selected");
    $(".text--one").removeClass("is-strikethrough");
    $(".circle--two").removeClass("is-selected");
    $(".text--two").addClass("is-grey");
    $(".check--one").addClass("is-hidden");
}

function incompleteStepThree() {
    $(".number--two").removeClass("is-hidden");
    $(".circle--two").addClass("is-selected");
    $(".circle--two").removeClass("is-completed");
    $(".check--two").addClass("is-hidden");
    $(".text--two").removeClass("is-strikethrough");
    $(".circle--three").removeClass("is-selected");
    $(".text--three").addClass("is-grey");
}

function incompleteStepsOneTwo() {
    $(".number--one, .number--two").removeClass("is-hidden");
    $(".circle--one").addClass("is-selected");
    $(".circle--two").removeClass("is-completed");
    $(".check--one, .check--two").addClass("is-hidden");
    $(".text--one, .text--two").removeClass("is-strikethrough");
    $(".circle--two, .circle--three").removeClass("is-selected");
    $(".text--two, .text--three").addClass("is-grey");
}

// Show panels
function showPanelOne() {
    $(".inner--one").fadeIn();
    $(".inner--one").removeClass("is-hidden");

    // Hide panels two and three
    $(".inner--two").fadeOut();
    $(".inner--two").addClass("is-hidden");
    $(".inner--spend").fadeOut();
    $(".inner--spend").addClass("is-hidden");
}

function showPanelHim() {
    $(".panel--him").fadeIn();
    $(".inner--him").fadeIn();
    $(".panel--him").removeClass("is-hidden");
    $(".inner--him").removeClass("is-hidden");

    // Hide panels one and three
    $(".inner--one").fadeOut();
    $(".inner--one").addClass("is-hidden");
    $(".inner--spend").fadeOut();
    $(".inner--spend").addClass("is-hidden");
}

function showPanelHer() {
    $(".panel--her").fadeIn();
    $(".inner--she").fadeIn();
    $(".panel--her").removeClass("is-hidden");
    $(".inner--she").removeClass("is-hidden");

    // Hide panels one and three
    $(".inner--one").fadeOut();
    $(".inner--one").addClass("is-hidden");
    $(".inner--spend").fadeOut();
    $(".inner--spend").addClass("is-hidden");
}

function showPanelAnyone() {
    $(".panel--anyone").fadeIn();
    $(".inner--anyone").fadeIn();
    $(".panel--anyone").removeClass("is-hidden");
    $(".inner--anyone").removeClass("is-hidden");

    // Hide panels one and three
    $(".inner--one").fadeOut();
    $(".inner--one").addClass("is-hidden");
    $(".inner--spend").fadeOut();
    $(".inner--spend").addClass("is-hidden");
}

function showPanelThree() {
    $(".panel--three").fadeIn();
    $(".inner--spend").fadeIn();
    $(".panel--three").removeClass("is-hidden");
    $(".inner--spend").removeClass("is-hidden");

    // Hide panels one and two
    $(".inner--one").fadeOut();
    $(".inner--one").addClass("is-hidden");
    $(".inner--two").fadeOut();
    $(".inner--two").addClass("is-hidden");
}

$(".btn--next").on("click", function(){

    // Progress bar circles
    let circleOneSelected = $(".circle--one").hasClass("is-selected");
    let circleTwoSelected = $(".circle--two").hasClass("is-selected");
    let circleThreeSelected = $(".circle--three").hasClass("is-selected");

    // Panel One options
    let giftsforHimSelected = $(".btn--option-him").hasClass("is-selected");
    let giftsforHerSelected = $(".btn--option-her").hasClass("is-selected");
    let giftsforKidsSelected = $(".btn--option-kids").hasClass("is-selected");
    let giftsforAnyoneSelected = $(".btn--option-anyone").hasClass("is-selected");

    // Panel Two options
    let typeHimJewelry = $(".btn--option-him-jewelry").hasClass("is-selected");
    let typeHimScarves = $(".btn--option-him-scarves").hasClass("is-selected");
    let typeHimFishing = $(".btn--option-him-fishing").hasClass("is-selected");
    let typeHimCologne = $(".btn--option-him-cologne").hasClass("is-selected");
    let typeHimShirts = $(".btn--option-him-shirts").hasClass("is-selected");
    let typeHimSports = $(".btn--option-him-sports").hasClass("is-selected");

    // Panel Three options
    let under25 = $(".btn--option-25").hasClass("is-selected");
    let under50 = $(".btn--option-50").hasClass("is-selected");
    let under75 = $(".btn--option-75").hasClass("is-selected");
    let under100 = $(".btn--option-100").hasClass("is-selected");
    let under250 = $(".btn--option-u250").hasClass("is-selected");
    let over250 = $(".btn--option-o250").hasClass("is-selected");

    let btnLikeSelected = $(".btn--like").hasClass("is-selected");


    if (circleOneSelected) {
        if (giftsforHimSelected) {
            completeStepOne();
            showPanelHim();
        } else if (giftsforHerSelected) {
            completeStepOne();
            showPanelHer();
        } else if (giftsforKidsSelected) {
            completeStepsOneTwo();
            showPanelThree();
        } else if (giftsforAnyoneSelected) {
            completeStepOne();
            showPanelAnyone();
        }
    }

    if (circleTwoSelected && btnLikeSelected) {
        completeStepTwo();
        showPanelThree();
    }

    if (circleThreeSelected && btnSpendSelected) {
        // Do action
    }
});

$(".btn--previous").on("click", function(){

    // Progress bar circles
    let circleOneSelected = $(".circle--one").hasClass("is-selected");
    let circleTwoSelected = $(".circle--two").hasClass("is-selected");
    let circleThreeSelected = $(".circle--three").hasClass("is-selected");

    // Panel One options
    let giftsforHimSelected = $(".btn--option-him").hasClass("is-selected");
    let giftsforHerSelected = $(".btn--option-her").hasClass("is-selected");
    let giftsforKidsSelected = $(".btn--option-kids").hasClass("is-selected");
    let giftsforAnyoneSelected = $(".btn--option-anyone").hasClass("is-selected");

    // Panel Two options
    let typeHimJewelry = $(".btn--option-him-jewelry").hasClass("is-selected");
    let typeHimScarves = $(".btn--option-him-scarves").hasClass("is-selected");
    let typeHimFishing = $(".btn--option-him-fishing").hasClass("is-selected");
    let typeHimCologne = $(".btn--option-him-cologne").hasClass("is-selected");
    let typeHimShirts = $(".btn--option-him-shirts").hasClass("is-selected");
    let typeHimSports = $(".btn--option-him-sports").hasClass("is-selected");

    // Panel Three options
    let under25 = $(".btn--option-25").hasClass("is-selected");
    let under50 = $(".btn--option-50").hasClass("is-selected");
    let under75 = $(".btn--option-75").hasClass("is-selected");
    let under100 = $(".btn--option-100").hasClass("is-selected");
    let under250 = $(".btn--option-u250").hasClass("is-selected");
    let over250 = $(".btn--option-o250").hasClass("is-selected");

    let btnLikeSelected = $(".btn--like").hasClass("is-selected");
    let btnHimSelected = $(".btn--him").hasClass("is-selected");

    if (circleOneSelected) {

    }

    if (circleTwoSelected) {
        incompleteStepTwo();
        showPanelOne();
    }

    if (circleThreeSelected) {


        if (giftsforHimSelected) {
            incompleteStepThree();
            showPanelHim();
        } else if (giftsforHerSelected) {
            incompleteStepThree();
            showPanelHer();
        } else if (giftsforKidsSelected) {
            incompleteStepsOneTwo();
            showPanelOne();
        } else if (giftsforAnyoneSelected) {
            incompleteStepThree();
            showPanelAnyone();
        }
    }
});

的index.html

    <!-- Panel One -->
    <div class="panel panel--one">

        <div class="advertising advertising--horizontal">
            <img src="http://placehold.it/720x90">
        </div>

        <section class="panel__progress">
            <ul>
                <li>
                    <div class="panel__pick">
                        <p class="panel__circle circle--one is-selected">
                            <i class="fa fa-check check--one is-hidden" aria-hidden="true"></i>
                            <span class="panel__number number--one">1</span>
                        </p>
                        <p class="panel__text text--one">Choose a category</p>
                    </div>
                </li>
                <li>
                    <div class="panel__pick">
                        <p class="panel__circle circle--two">
                            <i class="fa fa-check check--two is-hidden" aria-hidden="true"></i>
                            <span class="panel__number number--two">2</span>
                        </p>
                        <p class="panel__text text--two is-grey">Pick some items</p>
                    </div>
                </li>
                <li>
                    <div class="panel__pick">
                        <p class="panel__circle circle--three">
                            <i class="fa fa-check check--three is-hidden" aria-hidden="true"></i>
                            <span class="panel__number number--three">3</span>
                        </p>
                        <p class="panel__text text--three is-grey">Name your budget</p>
                    </div>
                </li>
            </ul>
        </section> <!-- .panel__progress -->

        <div class="test">
            <div class="panel__inner inner--one">
                <div class="panel__info">
                    <h2 class="panel__title">Who is the gift for?</h2>
                    <h3 class="panel__instructions pick--one">Pick one of the options below</h3>
                    <!-- <h3 class="panel__instructions">Eeny, meeny, miny, moe</h3> -->
                </div>

                <div class="button__group group--quarter">
                    <button class="btn btn--option btn--option-him btn--who">Gifts for him <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-her btn--who">Gifts for her <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-kids btn--who">Gifts for kids <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-anyone btn--who">Gifts for anyone <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                </div>

                <div class="button__group button__controls">
                    <a href="/index.html"><button class="btn btn--previous previous--one"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> Previous</button></a>
                    <button class="btn btn--next next--one">Next <i class="fa fa-long-arrow-right" aria-hidden="true"></i></button>
                </div>
            </div> <!-- .panel__inner -->
        </div>
    </div> <!-- .panel .panel--one -->

    <!-- Panel Two -->
    <!-- Gifts for Him -->
    <div class="panel panel--two panel--him is-hidden">

        <div class="test">
            <div class="panel__inner inner--two inner--him">
                <div class="panel__info">
                    <h2 class="panel__title">What are some things he might like?</h2>
                    <h3 class="panel__instructions pick--three">Pick three items below to help us narrow your search</h3>
                </div>

                <div class="button__group">
                    <button class="btn btn--option btn--option-him-jewelry btn--like">Jewelry <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-him-scarves btn--like">Scarves <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-him-fishing btn--like">Fishing <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-him-cologne btn--like">Cologne <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-him-shirts btn--like">Shirts <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                    <button class="btn btn--option btn--option-him-sports btn--like">Sports apparel <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                </div>

                <div class="button__group button__controls">
                    <button class="btn btn--previous previous--two"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> Previous</button>
                    <button class="btn btn--next next--two">Next <i class="fa fa-long-arrow-right" aria-hidden="true"></i></button>
                </div>
            </div> <!-- .panel__inner -->
        </div> <!-- .test -->
    </div> <!-- .panel .panel--two -->

    <!-- Panel Two -->
    <!-- Gifts for Her -->
    <div class="panel panel--two panel--her is-hidden">

<!--     <div class="advertising advertising--horizontal">
        <img src="http://placehold.it/720x90">
    </div> -->

        <div class="panel__inner inner--two inner--she">
            <div class="panel__info">
                <h2 class="panel__title">What are some things she might like?</h2>
                <h3 class="panel__instructions pick--three">Pick three items below to help us narrow your search</h3>
            </div>

            <div class="button__group">
                <button class="btn btn--option btn--like">Cashmere <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Perfume <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Scarves <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Sweaters <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Beauty <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Candles <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Necklaces <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Sports jewelry <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Watches <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
            </div>

            <div class="button__group button__controls">
                <button class="btn btn--previous previous--two"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> Previous</button>
                <button class="btn btn--next next--two">Next <i class="fa fa-long-arrow-right" aria-hidden="true"></i></button>
            </div>
        </div> <!-- .panel__inner -->
    </div> <!-- .panel .panel--two -->

    <!-- Panel Two -->
    <!-- Gifts for Anyone -->
    <div class="panel panel--two panel--anyone is-hidden">

<!--     <div class="advertising advertising--horizontal">
        <img src="http://placehold.it/720x90">
    </div> -->

        <div class="panel__inner inner--two inner--anyone">
            <div class="panel__info">
                <h2 class="panel__title">What are some things they might like?</h2>
                <h3 class="panel__instructions pick--three">Pick three items below to help us narrow your search</h3>
            </div>

            <div class="button__group">
                <button class="btn btn--option btn--like">Cookbooks <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Spirits <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Suitcases / bags <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Food<i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Gardening <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Gadgets <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Made in St. Louis <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Gifts that give back <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Fitness <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Subscriptions <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Ornaments <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Pets <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Personalized <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like">Other <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--like is-hidden"> <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
            </div>

            <div class="button__group button__controls">
                <button class="btn btn--previous previous--two"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> Previous</button>
                <button class="btn btn--next next--two">Next <i class="fa fa-long-arrow-right" aria-hidden="true"></i></button>
            </div>
        </div> <!-- .panel__inner -->
    </div> <!-- .panel .panel--two -->


    <!-- Panel Three -->
    <div class="panel panel--three is-hidden">

<!--     <div class="advertising advertising--horizontal">
        <img src="http://placehold.it/720x90">
    </div> -->

        <div class="panel__inner inner--spend">
            <div class="panel__info">
                <h2 class="panel__title">How much do you want to spend?</h2>
                <h3 class="panel__instructions pick--one">Pick one of the options below</h3>
                <!-- <h3 class="panel__instructions">Remember, it's the thought that counts</h3> -->
            </div>

            <div class="button__group">
                <button class="btn btn--option btn--option-25 btn--spend">Under $25 <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--option-50 btn--spend">Under $50 <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--option-75 btn--spend">Under $75 <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--option-100 btn--spend">Under $100 <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--option-u250 btn--spend">Under $250 <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
                <button class="btn btn--option btn--option-o250 btn--spend">$250 and over <i class="fa fa-check is-grey" aria-hidden="true"></i></button>
            </div>

            <div class="button__group button__controls">
                <button class="btn btn--previous previous--three"><i class="fa fa-long-arrow-left" aria-hidden="true"></i> Previous</button>
                <a href="/gifts.html"><button class="btn btn--next next--three">Next <i class="fa fa-long-arrow-right" aria-hidden="true"></i></button></a>
            </div>
        </div> <!-- .panel__inner -->
    </div> <!-- .panel .panel--three -->

app.css

/*----------------------------------
BUTTONS
----------------------------------*/
.button__group {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  width: 75%;
  margin-top: 15px;
  margin-bottom: 15px;
  margin: 0 auto;
  padding-left: 30px;
}
.button__group.group--quarter {
  width: 50%;
}
.button__controls {
  margin-top: 60px;
  margin-bottom: 60px;
}
button {
  display: block;
  margin-top: 15px;
  margin-bottom: 15px;
  padding: 20px;
  padding-right: 60px;
  padding-left: 60px;
  cursor: pointer;
  text-align: left;
  border: none;
  background: #ffffff;
}
.btn--previous,
.btn--next,
.btn--buy,
.btn--all,
.btn--recommend,
.btn--option {
  text-transform: uppercase;
  border-radius: 3px;
  font-family: "Roboto", sans-serif;
  font-size: 1.4rem;
  font-weight: 700 !default;
}
.btn--previous,
.btn--next {
  display: inline;
  margin-right: 30px;
  min-width: 225px;
  text-align: center;
}
.btn--all,
.btn--recommend,
.btn--option {
  border: 1px solid #aaaaaa;
}
.btn--previous {
  color: #c62828;
  border: 1px solid #c62828;
}
.btn--previous .fa-long-arrow-left {
  color: #c62828;
}
.btn--all,
.btn--recommend,
.btn--option {
  font-weight: 400;
  text-transform: none;
  color: #212121;
  display: inline-block;
  margin-right: 30px;
  min-width: 225px;
  min-height: 75px;
  border-bottom: 2px solid #aaaaaa;
}
.btn--all,
.btn--recommend {
  background: #c62828;
  border: none;
  color: #fff;
  font-weight: 700;
  text-align: center;
}
.btn--all:hover,
.btn--recommend:hover {
  background: #990000;
  border: none;
}
.btn--option {
  text-align: left;
  padding-left: 30px;
  min-width: 260px;
  min-height: 75px;
  font-size: 1.6rem;
}
.btn--option.is-selected {
  border: 2px solid #c62828;
  color: #c62828;
}
.btn--option .fa-check {
  color: #c62828;
  float: right;
  position: relative;
  right: -40px;
  top: -1px;
}
.btn--option .fa-check.is-grey {
  color: #e7e7e7;
}
.btn--option .fa-check.is-red {
  color: #c62828;
}
.btn--sidebar {
  font-weight: 400;
  text-transform: none;
  margin: 0;
  font-size: 1.6rem;
  padding-left: 15px;
  font-family: "Roboto";
  background: transparent;
  color: #212121;
  margin-top: 15px;
  padding-top: 5px;
  padding-bottom: 5px;
}
.btn--sidebar:hover {
  color: #aaaaaa;
  color: #ccc;
}
.btn--next,
.btn--buy {
  color: #ffffff;
  border: none;
  background: #c62828;
}
.btn--buy {
  margin: 0;
  width: 100%;
  text-align: center;
  margin-top: 15px;
  text-decoration: none;
}
.btn--buy:visited {
  text-decoration: none;
}
.btn--view {
  border: none;
  margin-bottom: 0;
}
.btn--view:hover {
  color: #212121;
}
.btn--next {
  border-bottom: 2px solid #990000;
}
.btn--next:hover {
  background: #990000;
  transition: 0.2s;
}
/* Custom query */
@media (max-width: 1250px) {
  .button__group {
    width: 80%;
  }
  .button__group.group--quarter {
    width: 70%;
  }
}
/* Large devices */
@media (max-width: 1200px) {
  .button__group {
    width: 90%;
  }
}
/* Large devices */
@media (max-width: 1024px) {
  .button__group {
    width: 100%;
  }
  .button__group.group--quarter {
    width: 85%;
  }
}
/* Medium devices */
@media (max-width: 768px) {
  .button__group {
    width: 100%;
  }
  .button__group.group--quarter {
    width: 100%;
  }
}
/* Medium devices */
/* Small devices */
@media (max-width: 480px) {
  .btn--option {
    min-width: 275px;
  }
  .btn--all,
  .btn--recommend {
    min-width: 275px;
  }
}


/*----------------------------------
LIST
----------------------------------*/
ul {
  padding: 0;
}
ul li {
  display: inline-block;
  margin-right: 15px;
  text-align: center;
}
.panel {
  width: 100%;
  height: 100%;
  position: relative;
}
.panel.is-hidden {
  display: none;
}
.panel__progress {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
}
.panel__circle {
  width: 50px;
  height: 50px;
  margin: 0 auto;
  padding: 15px;
  border: 1px solid #aaaaaa;
  border-radius: 50%;
  font-size: 1.6rem;
  font-weight: 300 !default;
}
.panel__circle.is-selected {
  color: #ffffff;
  border: none;
  background: #c62828;
}
.panel__circle.is-completed {
  border: 1px solid #c62828;
}
.panel__circle.is-completed .fa-check {
  color: #c62828;
}
.panel__text {
  font-family: "Roboto", sans-serif;
  font-size: 1.4rem;
}
.panel__number {
  position: relative;
  top: -22px;
}
.panel__number.is-hidden {
  display: none;
}
.panel__pick {
  padding: 15px;
  text-align: center;
}
.panel__title {
  font-family: "Merriweather";
  font-weight: 900;
  text-transform: none;
  margin-top: 30px;
  font-size: 4rem;
}
.panel__instructions {
  text-align: center;
  font-weight: 400;
  font-family: "Open Sans";
  font-size: 1.8rem;
  color: #aaaaaa;
  margin: 0;
  margin-top: 15px;
  margin-bottom: 30px;
}
/* Large devices */
/* Large devices */
/* Custom query */
@media (max-width: 875px) {
  .panel__title {
    width: 80%;
    margin: auto;
    margin-top: 30px;
  }
}
/* Medium devices */
/* Medium devices */
@media (max-width: 640px) {
  .panel__circle,
  .panel__text {
    display: none;
  }
}
/* Small devices */
@media (max-width: 480px) {
  .panel__title {
    font-size: 3.5rem;
  }
}

最佳答案 在CSS中使用转换和可见性的组合

.element {
  visibility:hidden;
  opacity:0;
  transition:opacity 0.5s linear;
}
.element.is-selected {
  visibility:visible;
  opacity:1;
}