@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500&display=swap');

:root {
  --font-size: 16px;
  --border-radius: 15px;
  --transition: all 0.3s ease;

  --base-color: #bbb;
  --primary-color: #00acc1;
  --secondary-color: #eee;
  --bg-gradient: linear-gradient(135deg, #1b2936 0%, #040c14 100%);
  --box-bg: rgba(0, 0, 0, 0.5);
  --box-shadow: 0 15px 35px rgba(0, 0, 0, 0.5);
  --box-border: rgba(255, 255, 255, 0.2);
  --input-border: rgba(255, 255, 255, 0.3);
  --label-color: rgba(255, 255, 255, 0.7);
  --select-option-bg: #0b1220;
  --button-hover-text: #fff;
}

:root[data-theme="light"] {
  --base-color: #222;
  --primary-color: #00acc1;
  --secondary-color: #333;
  --bg-gradient: linear-gradient(135deg, #77f 0%, #bbf 100%);
  --box-bg: rgba(200, 200, 200, 0.5);
  --box-shadow: 0 15px 35px rgba(80, 80, 80, 0.5);
  --box-border: rgba(0, 0, 0, 0.2);
  --input-border: rgba(0, 0, 0, 0.3);
  --label-color: rgba(0, 0, 0, 0.7);
  --select-option-bg: #eef;
  --button-hover-text: #000;
}

:root {
  color-scheme: dark light;
  font-size: var(--font-size, 16px);
  color: var(--base-color);
}

*:disabled {
  opacity: 0.4;
  cursor: initial;
}

html, body {
  height: 100vh;
  width: 100vw;
  margin: 0;
  padding: 0;
  background: var(--bg-gradient);
  font-family: 'Roboto', sans-serif;
  overflow-x: hidden;
}

.container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0 1rem;
}

.lang-content {
  display: none;
}
:root:has(#language option[value="ja"]:checked) .ja,
:root:has(#language option[value="en"]:checked) .en {
  display: initial;
}

details {
  cursor: pointer;
}

button {
  background: none;
  border: none;
  font-size: 1.5em;
  cursor: pointer;
  transition: var(--transition);
}

section + section {
  margin-top: 1.5em;
}

.main-box {
  position: relative;
  width: 30em;
  padding: 4em;
  background: var(--box-bg);
  backdrop-filter: blur(10px);
  box-sizing: border-box;
  box-shadow: var(--box-shadow);
  border-radius: var(--border-radius);
  border: 1px solid var(--box-border);
  animation: fadeIn 1s ease-in-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translate(0%, -200%);
  }
  to {
    opacity: 1;
    transform: translate(0%, 0%);
  }
}

.main-box h2 {
  margin: 0 0 1.5em;
  padding: 0;
  color: var(--secondary-color);
  text-align: center;
  font-size: 2.5em;
  font-weight: 300;
  letter-spacing: 2px;
}

.main-box .field-box {
  position: relative;
  margin-bottom: 1.5em;
}

.main-box .field-box select,
.main-box .field-box input {
  width: 100%;
  padding: 15px 0;
  font-size: 1.2em;
  color: var(--secondary-color);
  margin-bottom: 0;
  border: none;
  border-bottom: 2px solid var(--input-border);
  outline: none;
  background: transparent;
  transition: var(--transition);
}

.main-box .field-box select option {
  background-color: var(--select-option-bg);
}

.main-box .field-box select:focus,
.main-box .field-box input:focus {
  border-bottom-color: var(--primary-color);
}

.main-box .field-box label {
  position: absolute;
  top: 15px;
  left: 0;
  padding: 0;
  font-size: 1.2em;
  color: var(--label-color);
  pointer-events: none;
  transition: var(--transition);
}

.main-box .field-box select ~ label,
.main-box .field-box input:focus ~ label,
.main-box .field-box input:valid ~ label {
  top: -20px;
  left: 0;
  color: var(--primary-color);
  font-size: 0.9em;
  font-weight: 500;
}

.main-box form .a {
  position: relative;
  display: inline-block;
  padding: 15px 30px;
  color: var(--primary-color);
  font-size: 1.2em;
  text-decoration: none;
  text-transform: uppercase;
  overflow: hidden;
  transition: var(--transition);
  margin-top: 50px;
  letter-spacing: 4px;
  background-color: transparent;
  border: 2px solid var(--primary-color);
  border-radius: var(--border-radius);
  cursor: pointer;
  width: 100%;
  text-align: center;
}

.main-box .a:focus,
.main-box .a:hover {
  outline: none;
  background: var(--primary-color);
  color: var(--button-hover-text);
  box-shadow: 0 0 20px var(--primary-color),
              0 0 40px var(--primary-color),
              0 0 80px var(--primary-color);
  transform: translateY(-2px);
}

.main-box .a span {
  position: absolute;
  display: block;
}

.main-box .a span:nth-child(1) {
  top: 0;
  left: -100%;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--primary-color));
  animation: btn-anim1 2s linear infinite;
}

@keyframes btn-anim1 {
  0% {
    left: -100%;
  }
  50%,100% {
    left: 100%;
  }
}

.main-box .a span:nth-child(2) {
  top: -100%;
  right: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(180deg, transparent, var(--primary-color));
  animation: btn-anim2 2s linear infinite;
  animation-delay: 0.5s;
}

@keyframes btn-anim2 {
  0% {
    top: -100%;
  }
  50%,100% {
    top: 100%;
  }
}

.main-box .a span:nth-child(3) {
  bottom: 0;
  right: -100%;
  width: 100%;
  height: 2px;
  background: linear-gradient(270deg, transparent, var(--primary-color));
  animation: btn-anim3 2s linear infinite;
  animation-delay: 1s;
}

@keyframes btn-anim3 {
  0% {
    right: -100%;
  }
  50%,100% {
    right: 100%;
  }
}

.main-box .a span:nth-child(4) {
  bottom: -100%;
  left: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(360deg, transparent, var(--primary-color));
  animation: btn-anim4 2s linear infinite;
  animation-delay: 1.5s;
}

@keyframes btn-anim4 {
  0% {
    bottom: -100%;
  }
  50%,100% {
    bottom: 100%;
  }
}

/* Responsive Design */
@media (max-width: 480px) {
  .main-box {
    width: 90%;
    padding: 30px;
  }

  .main-box h2 {
    font-size: 2em;
  }

  .main-box .field-box input,
  .main-box .field-box label {
    font-size: 1em;
  }

  .main-box form .a {
    font-size: 1em;
    padding: 12px 20px;
  }
}

.align-right {
  text-align: right;
}

.align-center {
  text-align: center;
}

.field-box.align-right input.code-6 {
  width: 7em;
  text-align: center;
}

.field-box.align-right input.code-16 {
  width: 17em;
  text-align: center;
}

summary {
  margin-bottom: 1rem;
}

.main-box.wide {
  width: 46em;
}

.powered-footer {
  text-align:right;
  margin:0.5em;
}