:root {
  --bg-primary-color: #24292e;
  --bg-secondary-color: #1a1f25;
}

*, *::after, *::before {
  box-sizing: border-box;
}

body {
  overflow: hidden;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background-color: var(--bg-primary-color);
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  height: 100vh;
  overflow-x: hidden;
}

/* MENU */

#menu {
  position: absolute;
  overflow-y: auto;
  top: 66px; left: 0;
  width: 350px;
  height: calc(100vh - 66px);
  background-color: var(--bg-secondary-color);
  border-right: #28364a solid 2px;
  color: white;
  z-index: 999;
}

#menu-header-container {
  position: absolute;
  top: 0; left: 0;
  width: 350px;
  height: 66px;
  z-index: 999;
}

.menu-header {
  background-color: var(--bg-secondary-color);
  border-right: #28364a solid 2px;
  color: white;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: #28364a solid 2px;
}

#screen-cover {
  position: absolute;
  top: 0; left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(0, 10, 25, 0.3);
  backdrop-filter: blur(4px);
  z-index: 998;
}

.menu-title {
  font-size: 1rem;
  margin: 16px;
}

.menu-button {
  margin: 16px;
  width: 32px;
  height: 32px;
  border-radius: 4px;
  background: none;
  border: none;
  transition: background-color 50ms linear;
}

.menu-button:hover {
  background-color: rgba(255, 255, 255, 0.2);
  cursor: pointer;
}

.open-menu-button {
  position: absolute;
  top: 0; left: 0;
  margin: 16px 0 0 16px;
}

.menu-content {
  display: flex;
  flex-direction: column;
}

.menu-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  margin: 16px;
}

.menu-separator {
  width: 100%;
  height: 2px;
  background-color: #28364a;
}

input[type="radio"], input[type="checkbox"] {
  display: none;
}

label[for="type-hiragana"], label[for="type-katakana"] {
  letter-spacing: .2rem;
}

input[name="kana-type"] + label {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-size: 1rem;
  width: 100%;
  height: 3rem;
  background-color: #28364a;
  border-radius: 4px;
  transition: background-color 50ms linear;
}

input[name="kana-type"] + label span {
  font-size: .65rem;
}

input[name="kana-type"] + label:hover {
  background-color: #2d3c51;
  cursor: pointer;
}

input[name="kana-type"]:checked + label {
  background-color: #393;
}

input[name="hiragana"] + label, input[name="katakana"] + label {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-size: 1rem;
  letter-spacing: 1rem;
  text-indent: 1rem;
  width: 100%;
  height: 2rem;
  background-color: #28364a;
  border-radius: 4px;
  transition: background-color 50ms linear;
}

input[name="hiragana"] + label:hover, input[name="katakana"] + label:hover {
  background-color: #2d3c51;
  color: transparent;
  cursor: pointer;
}


input[name="hiragana"]:checked + label {
  background-color: rgb(41, 121, 187);
}

input[name="katakana"]:checked + label {
  background-color: rgb(199, 67, 67);
}

input[name="hiragana"] + label span, input[name="katakana"] + label span {
  font-size: .65rem;
}

input[name="hiragana"] + label::after, input[name="katakana"] + label::after {
  color: white;
  letter-spacing: normal;
  text-indent: 0;
  word-spacing: .8rem;
  position: absolute;
  opacity: 0;
}

input[name="hiragana"] + label:hover::after, input[name="katakana"] + label:hover::after {
  opacity: 1;
}

#hiragana-a + label::after, #katakana-a + label::after {
  word-spacing: 1.3rem;
  content: "a i u e o";
}

#hiragana-ka + label::after, #katakana-ka + label::after {
  content: "ka ki ku ke ko";
}

#hiragana-sa + label::after, #katakana-sa + label::after {
  content: "sa shi su se so";
}

#hiragana-ta + label::after, #katakana-ta + label::after {
  content: "ta chi tsu te to";
}

#hiragana-na + label::after, #katakana-na + label::after {
  content: "na ni nu ne no";
}

#hiragana-ha + label::after, #katakana-ha + label::after {
  content: "ha hi fu he ho";
}

#hiragana-ma + label::after, #katakana-ma + label::after {
  word-spacing: .5rem;
  content: "ma mi mu me mo";
}

#hiragana-ya + label::after, #katakana-ya + label::after {
  content: "ya yu yo";
}

#hiragana-ra + label::after, #katakana-ra + label::after {
  content: "ra ri ru re ro";
}

#hiragana-wa + label::after, #katakana-wa + label::after {
  content: "wa wo n";
}

#hiragana-ga + label::after, #katakana-ga + label::after {
  content: "ga gi gu ge go";
}

#hiragana-za + label::after, #katakana-za + label::after {
  content: "za ji zu ze zo";
}

#hiragana-da + label::after, #katakana-da + label::after {
  content: "da ji zu de do";
}

#hiragana-ba + label::after, #katakana-ba + label::after {
  content: "ba bi bu be bo";
}

#hiragana-pa + label::after, #katakana-pa + label::after {
  content: "pa pi pu pe po";
}

::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-thumb {
  border-radius: 4px;
  background-color: #667;
}

::-webkit-scrollbar-thumb:hover {
  background: #445; 
}

/* DISPLAY */

#display {
  display: flex;
  font-size: 1.5rem;
  font-weight: 600;
  gap: 2rem;
}

.card {
  display: flex;
  flex-direction: column;
  place-items: center;
}

.card p {
  color: #f44;
  height: 1rem;
}

.kana {
  display: grid;
  place-items: center;
  color: white;
  font-size: 4rem;
  font-weight: 900;
  width: 8rem;
  height: 8rem;
  border: #666 solid 4px;
  background-color: #555;
  border-radius: 50%;
}

#curr {
  border: #bbb solid 4px;
  background-color: #888;
  transition: opacity 0.05s linear;
}

#prev, #next {
  color: #24292e;
  font-size: 3rem;
  width: 6rem;
  height: 6rem;
  opacity: 0.5;
}

#prev2, #next2 {
  color: #24292e;
  font-size: 2rem;
  width: 4rem;
  height: 4rem;
  opacity: 0.25;
}

#prev, #prev2 {
  color: var(--bg-primary-color);
  background-color: var(--bg-primary-color);
  border: none;
}

.card:has(#prev2) p {
  opacity: 0.25;
}

/* STATS */

#stats {
  display: flex;
  margin-top: 25vh;
  font-weight: 400;
  color: white;
  opacity: 0.75;
  gap: 8rem;
}

#stats div {
  width: 150px;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stat + .stat {
  margin-top: 4rem;
}

.stat span {
  font-size: 3rem;
  font-weight: 700;
}



@media (max-height: 768px), (max-width: 750px) {
  #stats {
    margin-top: 10vh;
    gap: 2rem;
  }

  .stat + .stat {
    margin-top: 2rem;
  }

  .stat span {
    font-size: 2rem;
    font-weight: 700;
  }
}

@media (max-width: 650px) {
  #prev2, #next2 {
    display: none;
  }

  #menu {
    width: 100vw;
    height: 100vh;
  }

  #menu-header-container {
    width: 100vw;
    height: 66px;
  }
}

@media (max-height: 450px), (max-width: 480px) {
  #stats {
    display: none;
  }
}