:root {
  color-scheme: light;
  --paper: #f6f0e4;
  --paper-deep: #eee4d1;
  --card: #fbf7ec;
  --ink: #17191a;
  --muted: #5f5d57;
  --blue: #173b79;
  --blue-soft: #d7deed;
  --ochre: #a87822;
  --red: #a44637;
  --green: #2f6957;
  --rule: rgba(23, 25, 26, 0.22);
  --shadow: rgba(55, 43, 23, 0.14);
  --serif: Georgia, "Times New Roman", serif;
  --sans: "Avenir Next", Avenir, "Helvetica Neue", Arial, sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --paper: #171b22;
  --paper-deep: #222834;
  --card: #202733;
  --ink: #f2ecde;
  --muted: #bbb7ac;
  --blue: #8caeea;
  --blue-soft: #34435f;
  --ochre: #dbb466;
  --red: #e68170;
  --green: #76bca5;
  --rule: rgba(242, 236, 222, 0.2);
  --shadow: rgba(0, 0, 0, 0.35);
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  min-width: 320px;
  background: var(--paper);
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    radial-gradient(circle at 18% 33%, rgba(94, 72, 32, 0.035) 0 0.65px, transparent 0.8px),
    radial-gradient(circle at 72% 68%, rgba(94, 72, 32, 0.03) 0 0.55px, transparent 0.75px);
  background-size: 7px 9px, 11px 13px;
  font-family: var(--sans);
  text-rendering: optimizeLegibility;
}

button,
input {
  font: inherit;
}

button,
.logic-card {
  -webkit-tap-highlight-color: transparent;
}

button {
  color: inherit;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.site-header {
  height: 86px;
  padding: 0 clamp(24px, 4vw, 56px);
  border-bottom: 1px solid var(--rule);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.wordmark {
  color: var(--ink);
  text-decoration: none;
  display: inline-flex;
  flex-direction: column;
  line-height: 0.82;
}

.wordmark > span {
  font-family: var(--serif);
  font-size: 38px;
  letter-spacing: -0.045em;
}

.wordmark small {
  margin: 10px 0 0 2px;
  color: var(--blue);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.34em;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 26px;
}

.text-button {
  padding: 10px 0;
  border: 0;
  background: transparent;
  color: var(--blue);
  font-size: 15px;
  cursor: pointer;
}

.text-button::after {
  content: "";
  display: block;
  width: 0;
  height: 1px;
  margin-top: 3px;
  background: currentColor;
  transition: width 180ms ease;
}

.text-button:hover::after,
.text-button:focus-visible::after {
  width: 100%;
}

.theme-button,
.dialog-close {
  display: grid;
  place-items: center;
  background: transparent;
  cursor: pointer;
}

.theme-button {
  width: 46px;
  height: 46px;
  border: 1px solid var(--blue);
  border-radius: 50%;
  color: var(--blue);
}

.theme-button svg {
  width: 22px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-width: 1.6;
}

.theme-button:hover {
  color: var(--paper);
  background: var(--blue);
}

.task-shell {
  width: min(1280px, calc(100% - 48px));
  margin: 0 auto;
  padding: 35px 0 28px;
}

.intro {
  text-align: center;
}

.intro h1 {
  max-width: 1000px;
  margin: 0 auto;
  font-family: var(--serif);
  font-size: clamp(44px, 4.6vw, 68px);
  font-weight: 400;
  line-height: 1.04;
  letter-spacing: -0.045em;
}

.intro p {
  margin: 12px 0 28px;
  color: var(--muted);
  font-size: 19px;
}

.rule-panel {
  position: relative;
  min-height: 91px;
  border: 1px solid var(--ochre);
  display: grid;
  grid-template-columns: 245px 1fr;
  align-items: center;
  box-shadow: inset 0 0 0 5px var(--paper), inset 0 0 0 6px color-mix(in srgb, var(--ochre) 65%, transparent);
}

.rule-label {
  height: 58%;
  padding: 0 25px;
  border-right: 1px solid color-mix(in srgb, var(--ochre) 55%, transparent);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 15px;
}

.rule-label h2 {
  margin: 0;
  color: var(--ochre);
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.11em;
  text-transform: uppercase;
  white-space: nowrap;
}

.ornament {
  width: 24px;
  height: 1px;
  background: var(--ochre);
  opacity: 0.65;
}

.rule-panel > p {
  margin: 0;
  padding: 20px 40px;
  font-family: var(--serif);
  font-size: clamp(21px, 2vw, 27px);
  line-height: 1.35;
}

fieldset {
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 0;
}

.card-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: clamp(18px, 2.2vw, 32px);
  padding: 22px 28px 0;
}

.logic-card {
  position: relative;
  min-width: 0;
  aspect-ratio: 0.87;
  cursor: pointer;
  perspective: 1000px;
}

.logic-card input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.card-face {
  position: relative;
  width: 100%;
  height: 100%;
  padding: 14px;
  border: 1px solid color-mix(in srgb, var(--ochre) 52%, var(--rule));
  border-radius: 15px;
  background-color: var(--card);
  background-image: radial-gradient(circle at 30% 25%, rgba(130, 99, 42, 0.045) 0 0.7px, transparent 0.9px);
  background-size: 8px 8px;
  box-shadow: 3px 5px 0 var(--paper-deep), 5px 8px 18px var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: transform 180ms ease, border-color 180ms ease, box-shadow 180ms ease;
}

.card-face::before {
  content: "";
  position: absolute;
  inset: 10px;
  border: 1px dashed color-mix(in srgb, var(--blue) 75%, transparent);
  border-radius: 9px;
  pointer-events: none;
}

.card-value {
  margin-top: -3%;
  color: var(--blue);
  font-family: var(--serif);
  font-size: clamp(78px, 10vw, 136px);
  font-weight: 400;
  line-height: 0.9;
}

.card-divider {
  width: 55%;
  height: 1px;
  margin: 12% 0 8%;
  background: color-mix(in srgb, var(--ochre) 65%, transparent);
  display: flex;
  align-items: center;
  justify-content: center;
}

.card-divider i {
  width: 7px;
  height: 7px;
  background: var(--ochre);
  rotate: 45deg;
  box-shadow: 0 0 0 5px var(--card);
}

.card-kind {
  color: var(--blue);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.card-status {
  position: absolute;
  top: 22px;
  right: 22px;
  width: 25px;
  height: 25px;
  border: 1px solid transparent;
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: var(--card);
  font-size: 16px;
  font-weight: 800;
}

.logic-card:hover .card-face {
  transform: translateY(-5px) rotate(-0.4deg);
  border-color: var(--blue);
  box-shadow: 4px 7px 0 var(--paper-deep), 7px 12px 24px var(--shadow);
}

.logic-card:nth-child(even):hover .card-face {
  transform: translateY(-5px) rotate(0.4deg);
}

.logic-card input:focus-visible + .card-face {
  outline: 3px solid var(--blue);
  outline-offset: 5px;
}

.logic-card input:checked + .card-face {
  border: 2px solid var(--blue);
  transform: translateY(-7px);
  box-shadow: 4px 8px 0 var(--blue-soft), 7px 14px 26px var(--shadow);
}

.logic-card input:checked + .card-face .card-status {
  border-color: var(--blue);
  background: var(--blue);
}

.logic-card input:checked + .card-face .card-status::before {
  content: "✓";
}

.logic-card.is-correct .card-face {
  border-color: var(--green);
}

.logic-card.is-correct .card-status {
  border-color: var(--green);
  background: var(--green);
}

.logic-card.is-correct .card-status::before {
  content: "✓";
}

.logic-card.is-missed .card-face,
.logic-card.is-extra .card-face {
  border-color: var(--red);
}

.logic-card.is-missed .card-status,
.logic-card.is-extra .card-status {
  border-color: var(--red);
  background: var(--red);
}

.logic-card.is-missed .card-status::before {
  content: "!";
}

.logic-card.is-extra .card-status::before {
  content: "×";
}

.instruction {
  margin: 18px 0 9px;
  text-align: center;
  font-size: 17px;
}

.action-row {
  min-height: 77px;
  border-top: 1px solid var(--rule);
  display: grid;
  grid-template-columns: 210px minmax(260px, 480px) 210px;
  align-items: center;
  justify-content: center;
  gap: 22px;
}

.selection-count {
  margin: 0;
  color: var(--ink);
  font-size: 17px;
}

.selection-count strong {
  color: var(--blue);
  font-family: var(--serif);
  font-size: 30px;
  font-weight: 400;
}

.primary-button,
.reset-button {
  min-height: 54px;
  border-radius: 7px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 11px;
  font-size: 17px;
  font-weight: 650;
  cursor: pointer;
  transition: transform 150ms ease, background-color 150ms ease, color 150ms ease;
}

.primary-button {
  border: 1px solid var(--blue);
  background: var(--blue);
  color: var(--paper);
}

.primary-button svg,
.reset-button svg {
  width: 21px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.8;
}

.primary-button:hover:not(:disabled),
.reset-button:hover {
  transform: translateY(-2px);
}

.primary-button:disabled {
  border-color: var(--blue-soft);
  background: var(--blue-soft);
  color: color-mix(in srgb, var(--ink) 35%, transparent);
  cursor: not-allowed;
}

.reset-button {
  border: 1px solid var(--blue);
  background: transparent;
  color: var(--blue);
}

.reset-button:hover {
  background: var(--blue);
  color: var(--paper);
}

.feedback-panel {
  min-height: 80px;
  padding: 17px clamp(22px, 3vw, 46px);
  border: 1px dashed color-mix(in srgb, var(--ochre) 75%, transparent);
  display: flex;
  align-items: flex-start;
  gap: 22px;
  transition: border-color 180ms ease, background-color 180ms ease;
}

.feedback-icon {
  flex: 0 0 auto;
  width: 35px;
  height: 35px;
  border: 3px solid var(--ochre);
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: var(--ochre);
  font-family: var(--serif);
  font-size: 23px;
  font-style: italic;
  font-weight: 700;
  line-height: 1;
}

.feedback-copy {
  flex: 1;
}

.feedback-copy h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.35;
}

.feedback-copy > p {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.feedback-panel.success {
  border-color: var(--green);
  background: color-mix(in srgb, var(--green) 6%, transparent);
}

.feedback-panel.success .feedback-icon {
  border-color: var(--green);
  color: var(--green);
}

.feedback-panel.needs-work {
  border-color: var(--red);
  background: color-mix(in srgb, var(--red) 6%, transparent);
}

.feedback-panel.needs-work .feedback-icon {
  border-color: var(--red);
  color: var(--red);
}

.explanation-grid {
  margin-top: 17px;
  border-top: 1px solid var(--rule);
  display: grid;
  grid-template-columns: 1fr 1fr 1.4fr;
}

.explanation-grid article {
  padding: 15px 18px 0 0;
}

.explanation-grid article + article {
  padding-left: 18px;
  border-left: 1px solid var(--rule);
}

.explanation-grid span {
  color: var(--blue);
  font-family: var(--serif);
  font-size: 24px;
}

.explanation-grid p {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.45;
}

.guide-dialog {
  width: min(600px, calc(100% - 32px));
  padding: 44px;
  border: 1px solid var(--ochre);
  border-radius: 2px;
  background: var(--paper);
  color: var(--ink);
  box-shadow: 0 30px 80px rgba(0, 0, 0, 0.25);
}

.guide-dialog::backdrop {
  background: rgba(15, 18, 22, 0.58);
  backdrop-filter: blur(3px);
}

.dialog-close {
  position: absolute;
  top: 15px;
  right: 15px;
  width: 38px;
  height: 38px;
  border: 0;
  color: var(--blue);
}

.dialog-close svg {
  width: 22px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.7;
}

.dialog-number {
  margin: 0 0 24px;
  color: var(--ochre);
  font-family: var(--serif);
  font-size: 20px;
}

.guide-dialog h2 {
  margin: 0;
  max-width: 500px;
  font-family: var(--serif);
  font-size: 40px;
  font-weight: 400;
  line-height: 1.04;
  letter-spacing: -0.035em;
}

.guide-dialog > p:not(.dialog-number) {
  margin: 20px 0;
  color: var(--muted);
  font-size: 16px;
  line-height: 1.65;
}

.logic-example {
  padding: 18px 0;
  border-block: 1px solid var(--rule);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  color: var(--blue);
  font-size: 14px;
}

.logic-example b {
  color: var(--ochre);
}

.logic-example strong {
  color: var(--red);
}

.dialog-button {
  width: 100%;
  margin-top: 26px;
}

button:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--blue) 55%, transparent);
  outline-offset: 3px;
}

@media (max-width: 900px) {
  .task-shell {
    width: min(700px, calc(100% - 32px));
  }

  .rule-panel {
    grid-template-columns: 1fr;
  }

  .rule-label {
    height: auto;
    padding: 18px 20px 0;
    border-right: 0;
  }

  .rule-panel > p {
    padding: 13px 30px 24px;
    text-align: center;
  }

  .card-row {
    grid-template-columns: repeat(2, 1fr);
    padding-inline: 36px;
  }

  .action-row {
    grid-template-columns: 1fr 1.5fr;
  }

  .selection-count {
    grid-column: 1 / -1;
    justify-self: center;
    margin-top: 10px;
  }

  .explanation-grid {
    grid-template-columns: 1fr;
  }

  .explanation-grid article + article {
    padding-left: 0;
    border-top: 1px solid var(--rule);
    border-left: 0;
  }
}

@media (max-width: 560px) {
  .site-header {
    height: 72px;
    padding-inline: 18px;
  }

  .wordmark > span {
    font-size: 31px;
  }

  .wordmark small {
    font-size: 8px;
  }

  .header-actions {
    gap: 14px;
  }

  .text-button {
    font-size: 13px;
  }

  .theme-button {
    width: 40px;
    height: 40px;
  }

  .task-shell {
    width: calc(100% - 28px);
    padding-top: 27px;
  }

  .intro h1 {
    font-size: 39px;
  }

  .intro p {
    margin: 10px 15px 22px;
    font-size: 16px;
    line-height: 1.4;
  }

  .rule-panel > p {
    padding-inline: 20px;
    font-size: 20px;
  }

  .card-row {
    gap: 14px;
    padding: 18px 2px 0;
  }

  .card-face {
    border-radius: 11px;
  }

  .card-face::before {
    inset: 7px;
  }

  .card-value {
    font-size: clamp(72px, 26vw, 110px);
  }

  .card-kind {
    font-size: 10px;
  }

  .card-status {
    top: 14px;
    right: 14px;
  }

  .instruction {
    margin-block: 17px 13px;
    font-size: 15px;
  }

  .action-row {
    padding: 14px 0;
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .selection-count {
    grid-column: auto;
    grid-row: 1;
    margin-top: 0;
  }

  .primary-button,
  .reset-button {
    width: 100%;
  }

  .feedback-panel {
    margin-top: 8px;
    padding: 18px;
    gap: 14px;
  }

  .feedback-icon {
    width: 30px;
    height: 30px;
    border-width: 2px;
    font-size: 19px;
  }

  .guide-dialog {
    padding: 38px 24px 26px;
  }

  .guide-dialog h2 {
    font-size: 34px;
  }

  .logic-example {
    align-items: flex-start;
    flex-direction: column;
  }

  .logic-example b {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}