* {
  margin: 0;
  padding: 0;
}
html {
  height: 100%;
}
#top_bar {
  position: fixed;
  top: 0;
  width: 100%;
  height: 60px;
  background-color: #259b24;
  z-index: 5;
  box-shadow: 0 0 6px 2px #808080;
}
#footer {
  position: flex;
  bottom: 0;
  width: 100%;

  background-color: #259b24;
  z-index: 5;
  text-align: center;
  line-height: 30px;
  color: white;
}
#wrapper {
  height: 100%;

  transition: opacity 0.3s ease;
  -webkit-transition: opacity 0.3s ease;
  z-index: -1;
}
#mask {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  background-color: rgba(0, 0, 0, 0.6);
  z-index: 99;
}
#cum {
  margin-top: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.page_changer {
  margin: 0 30px;
  width: 40px;
  width: 40px;
  opacity: 0.6;
  transition: opacity 0.5s ease;
  -webkit-transition: opacity 0.5s ease;
  cursor: pointer;
}
.page_changer_active {
  opacity: 1;
}
#menu {
  position: absolute;
  width: 100px;
  top: 30px;
  right: 24px;
  background: #fff;
  box-shadow: 0 1px 6px #000;
  border-radius: 2px;
  padding: 10px 14px;
  display: none;
  opacity: 0;
  transition: opacity 0.5s ease;
  -webkit-transition: opacity 0.5s ease;
  cursor: pointer;
}
.menu_show {
  opacity: 1 !important;
  z-index: 7;
}
#about {
  overflow-y: auto;
  display: none;
  position: fixed;
  top: 50%;
  left: 50%;
  width: 400px;
  height: 500px;
  margin-top: -250px;
  margin-left: -200px;
  padding: 20px;
  background-color: white;
  box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.05), 0 1px 4px 0 rgba(0, 0, 0, 0.08),
    0 3px 1px -2px rgba(0, 0, 0, 0.2);
  z-index: 100;
  opacity: 0;
  transition: opacity 0.5s ease;
  -webkit-transition: opacity 0.5s ease;
}
.about_show {
  opacity: 1 !important;
}
a:link,
a:visited {
  text-decoration: none;
  color: #03a9f4;
}

.button_md {
  font-weight: bold;
  cursor: pointer;
  width: 100px;
  line-height: 40px;
  height: 40px;
  text-align: center;
  user-select: none;
  -webkit-user-select: none;
  display: inline-block;
  overflow: hidden;
  position: relative;
}
.button_flat {
  color: #259b24;
  background-color: rgba(0, 0, 0, 0);
  margin: 5px;
}

#about .button_md.button_flat {
  width: 100px;
  position: absolute;
  right: 10px;
  bottom: 10px;
}

.pages {
  height: calc(100vh - 90px);
  transition: left 0.5s ease;
  display: flex;
  justify-content: space-around;
  margin-top: 75px;
}
#page {
  /*动画*/
  animation-name: show;
  animation-fill-mode: forwards;
  animation-duration: 0.5s;
  display: none;
  margin: 0 10px;
  height: 100%;
  width: 300px;
  box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.05), 0 1px 4px 0 rgba(0, 0, 0, 0.08),
    0 3px 1px -2px rgba(0, 0, 0, 0.2);
  background-color: white;
  border-radius: 2px;
  overflow: auto;
  z-index: 1;
}
.page3 {
  flex: 1;
}
textarea {
  width: calc(100% - 20px);
  margin: 10px;
  border: none;
  border-bottom: solid 1px grey;
  overflow: hidden;
  outline: none;
}
textarea:focus {
  border-bottom: solid 2px #259b24;
}
.title {
  font-size: 18px;
  font-weight: bold;
  margin-left: 5px;
}
.describe {
  color: grey;
  font-size: 14px;
  padding: 5px;
}
#page.page_big {
  width: 600px;
  text-align: center;
}
.bg {
  margin-top: 15%;
}
#progress_range_value {
  width: 25px;
  text-align: center;
  outline: none;
  border: none;
  border-bottom: solid 1px grey;
}
#progress_range_value:focus {
  border-bottom: solid 2px #259b24;
}
.audio_btn:active {
  margin-top: 8px;
  box-shadow: 0px 1px 3px 1px #606060;
}
#progress_range {
  width: calc(100% - 200px);
  background-color: #259b24;
  border-radius: 3px;
  height: 3px;
  appearance: none;
  outline: none;
}
#progress_range::-webkit-slider-thumb {
  appearance: none;
  width: 12px;
  height: 12px;
  border-radius: 100%;
  background-color: #259b24;
}
#progress_range::-webkit-slider-thumb:hover {
  box-shadow: 0 0 0 2px #259b24;
}
#progress_range_max,
.num {
  width: 15px;
  outline: none;
  border: none;
  appearance: none;
  pointer-events: none;
}
.audio_btn {
  margin: 20px;
  width: 64px;
  height: 64px;
  border-radius: 100%;
  box-shadow: 0px 3px 6px 2px #bfbfbf;
  transition: box-shadow 0.2s ease;
  -webkit-transition: boxshadow 0.2s ease;
}
.audio_btn:active {
  margin-top: 8px;
  box-shadow: 0px 1px 3px 1px #606060;
}
.button_md {
  font-weight: bold;
  cursor: pointer;
  text-align: center;
  user-select: none;
  display: inline-block;
  overflow: hidden;
  position: relative;
}
#play_toggle {
  background: url(../img/play.svg);
}
#stop_btn {
  background: url(../img/stop.svg);
}
.keyboard {
  width: 168px;
  height: 150px;
  display: inline-block;
  margin-top: 10px;
  padding: 0;
  position: relative;
}
.white_key {
  width: 24px;
  height: 150px;
  position: absolute;
  background-color: white;
  border: solid;
  border-width: 1px;
  z-index: 2;
}
.white_key:active {
  background-color: grey;
}
.black_key {
  width: 16px;
  height: 95px;
  position: absolute;
  background-color: black;
  border: none;
  z-index: 9;
}
.black_key:active {
  background-color: grey;
}
.keyboard {
  width: 168px;
  height: 150px;
  display: inline-block;
  margin-top: 10px;
  padding: 0;
  position: relative;
}
.button {
  margin: 0;
  padding: 0;
  top: 0;
  cursor: pointer;
}
.key_txt {
  width: 100%;
  font-size: 16px;
  text-align: center;
  font-weight: bold;
  position: absolute;
  bottom: 10px;
  cursor: pointer;
}
.rest_key {
  width: 160px;
  height: 28px;
  font-size: bold;
  position: relative;
}
#keyboards {
  margin: 30% 20px 0px 20px;
}
.section {
  padding: 20px;
  word-break: break-all;
}
.button_float {
  margin: 15px;
  color: white;
  background-color: #259b24;
  box-shadow: 0px 3px 6px 2px #bfbfbf;
  transition: box-shadow 0.2s ease;
  -webkit-transition: boxshadow 0.2s ease;
}
.button_float:active {
  margin-top: 17px;
  box-shadow: 0px 1px 3px 1px #606060;
}
.note {
  position: absolute;
  top: 300px;
  left: 50%;
  width: 60px;
  /*动画*/
  animation-name: show;
  animation-fill-mode: forwards;
  animation-duration: 0.5s;
}
.seg_active {
  opacity: 1;
  transition: opacity 0.1s ease;
  -webkit-transition: opacity 0.1s ease;
}

@media only screen and (max-width: 680px) {
  .bg {
    margin-top: 8%;
    width: calc(100% - 20px);
  }
  #progress_range {
    width: calc(100% - 150px);
  }
  .keyboard {
    transform: rotate(90deg);
    margin: 7px 20px;
  }
  .rest_key {
    transform: rotate(90deg);
    position: relative;
    left: -120px;
    top: -286px;
  }
  #keyboards {
    margin: 10% 20px 0px 20px;
  }
}

@media screen and (max-width: 480px) {
  #about .button_md.button_flat {
    position: fixed;
    top: 108px;
  }
  #about .title {
    position: sticky;
    top: 0px;
    background-color: white;
    text-align: center;
    padding: 20px;
  }
  .bg {
    margin-top: 10px;
    width: calc(100% - 20px);
  }
  .pages {
    height: auto;
    transition: left 0.5s ease;
    display: flex;
    justify-content: hidden;
    flex-direction: column;
    margin-top: 75px;
    overflow: auto;
  }
  #page {
    margin: 10px;
    height: auto;
    width: calc(100% - 20px);
    overflow: auto;
  }
  #page.page_big {
    width: calc(100% - 20px);
  }
  #about {
    position: absolute;
    top: 200px;
    left: 10px;
    right: 10px;
    bottom: 200px;
    width: calc(100% - 20px);
  }
  #about {
    position: absolute;
    top: 100px;
    left: 10px;
    right: 10px;
    bottom: 100px;
    width: auto;
    height: auto;
    margin-top: 0px;
    margin-left: 0px;
    padding: 0px;
  }
  .keyboard {
    transform: rotate(90deg);
    margin: 7px 20px;
  }
  .rest_key {
    transform: rotate(90deg);
    position: relative;
    left: -120px;
    top: -286px;
  }
  #keyboards {
    margin: 10% 20px 0px 20px;
  }
}

@media (max-width: 1024px) and (max-height: 768px) {
  .bg {
    margin-top: 10px;
  }
}

@media (max-width: 900px) and (max-height: 480px) {
  .bg {
    margin-top: 5px;
    height: auto;
    width: 200px;
  }
  #keyboards {
    margin: 10% 20px 0px 20px;
  }
}
@media (max-width: 480px) and (max-height: 400px) {
  .bg {
    margin-top: 5px;
    height: auto;
    width: 150px;
  }
  #keyboards {
    margin: 10% 20px 0px 20px;
  }
}

@keyframes show {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}