:root {
  --teal: #0397a4;
  --teal-dark: #055f68;
  --text: #0f2430;
  --muted: #64748b;
  --border: rgba(5, 107, 117, 0.14);
  --shadow: 0 24px 60px rgba(8, 36, 43, 0.14);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 12% 12%, rgba(255, 214, 102, 0.32), transparent 0 22rem),
    radial-gradient(circle at 88% 10%, rgba(188, 238, 240, 0.58), transparent 0 18rem),
    linear-gradient(135deg, #e8f7f9 0%, #ffffff 52%, #fff7db 100%);
  color: var(--text);
  font-family: Nunito, Avenir, Helvetica, Arial, sans-serif;
}

.app-shell {
  width: min(100% - 2rem, 980px);
  margin: 0 auto;
  padding: 2rem 0 4rem;
}

.app-header {
  margin: 0 auto 1.5rem;
  text-align: center;
}

.back-link {
  display: flex;
  width: max-content;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 1.5rem;
  color: var(--teal-dark);
  font-weight: 800;
  text-decoration: none;
}

.back-link:hover {
  text-decoration: underline;
  text-underline-offset: 4px;
}

.eyebrow {
  display: inline-flex;
  margin: 0;
  border-radius: 999px;
  background: rgba(3, 151, 164, 0.12);
  padding: 0.4rem 0.75rem;
  color: var(--teal-dark);
  font-size: 0.72rem;
  font-weight: 900;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

h1 {
  margin: 1rem 0 0;
  font-size: clamp(2.4rem, 7vw, 4.7rem);
  line-height: 0.98;
  letter-spacing: -0.05em;
}

.app-header > p:last-child {
  margin: 1rem auto 0;
  max-width: 42rem;
  color: var(--muted);
  font-size: 1.1rem;
  line-height: 1.7;
}

.practice-card {
  border: 1px solid var(--border);
  border-radius: 2rem;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: var(--shadow);
  padding: clamp(1rem, 3vw, 2rem);
}

.mode-tabs {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.45rem;
  margin-bottom: 2rem;
  border-radius: 1.2rem;
  background: rgba(226, 242, 244, 0.7);
  padding: 0.45rem;
}

.mode-button {
  min-height: 2.75rem;
  border: 0;
  border-radius: 0.9rem;
  background: transparent;
  color: #526477;
  cursor: pointer;
  font-weight: 900;
}

.mode-button:hover,
.mode-button:focus-visible {
  background: rgba(255, 255, 255, 0.64);
  outline: none;
}

.mode-button.is-active {
  background: #ffffff;
  box-shadow: 0 10px 22px rgba(8, 36, 43, 0.08);
  color: var(--text);
}

.content-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 2rem;
  align-items: center;
}

.clock-wrap {
  display: grid;
  place-items: center;
}

#clock {
  width: min(100%, 320px);
  aspect-ratio: 1;
  border: 10px solid #d9eef1;
  border-radius: 999px;
  background: #ffffff;
  box-shadow: 0 18px 42px rgba(8, 36, 43, 0.12);
}

.practice-panel {
  min-width: 0;
}

.small-label,
.manual-controls label,
.quiz-controls label {
  margin: 0 0 0.5rem;
  color: #8392a5;
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.answer-text {
  min-height: 3.8rem;
  margin: 0;
  color: var(--teal-dark);
  font-size: clamp(1.7rem, 3.6vw, 2.65rem);
  font-weight: 950;
  line-height: 1.05;
  white-space: nowrap;
}

.digital-time {
  margin: 0.75rem 0 1.5rem;
  color: #8a98a8;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-weight: 800;
}

.manual-controls,
.quiz-controls {
  display: grid;
  gap: 0.75rem;
  margin: 1.25rem 0;
}

input {
  width: 100%;
  min-height: 3rem;
  border: 1px solid rgba(5, 107, 117, 0.18);
  border-radius: 1rem;
  padding: 0 1rem;
  color: var(--text);
  font: inherit;
  font-weight: 800;
}

input:focus {
  outline: none;
  box-shadow: 0 0 0 4px rgba(3, 151, 164, 0.12);
}

.time-slider {
  min-height: 1.6rem;
  padding: 0;
  accent-color: var(--teal);
  cursor: pointer;
}

.digital-time-builder {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  gap: 0.65rem;
  min-height: 4.8rem;
  border: 1px solid rgba(5, 107, 117, 0.18);
  border-radius: 1.35rem;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.98) 0%, rgba(238, 249, 250, 0.94) 100%);
  padding: 0.35rem 0.75rem;
  box-shadow: 0 18px 38px rgba(6, 70, 78, 0.1);
}

.digital-time-builder:focus-within {
  border-color: rgba(3, 151, 164, 0.38);
  box-shadow: 0 0 0 4px rgba(3, 151, 164, 0.12), 0 18px 38px rgba(6, 70, 78, 0.1);
}

.digital-number-input {
  min-height: 3.8rem;
  border: 0;
  border-radius: 1rem;
  background: transparent;
  color: var(--teal-dark);
  font-family: Nunito, Avenir, Helvetica, Arial, sans-serif;
  font-size: clamp(2.1rem, 7vw, 3.45rem);
  font-weight: 950;
  letter-spacing: 0.03em;
  text-align: center;
  -moz-appearance: textfield;
}

.digital-number-input::-webkit-outer-spin-button,
.digital-number-input::-webkit-inner-spin-button {
  margin: 0;
  -webkit-appearance: none;
}

.digital-number-input:focus {
  box-shadow: none;
}

.digital-time-separator {
  color: var(--teal-dark);
  font-size: clamp(2rem, 6vw, 3.2rem);
  font-weight: 950;
  line-height: 1;
}

.write-intro-button {
  justify-self: start;
  margin-top: 0.25rem;
}

.write-result {
  min-height: 1.5rem;
  margin: 0;
  color: var(--teal-dark);
  font-size: 1.15rem;
  font-weight: 900;
  line-height: 1.5;
}

.write-result:not(:empty) {
  border: 1px solid rgba(5, 107, 117, 0.16);
  border-radius: 1rem;
  background: rgba(238, 249, 250, 0.9);
  padding: 0.9rem 1rem;
}

.quick-times {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.quick-times button {
  border: 1px solid rgba(5, 107, 117, 0.16);
  border-radius: 999px;
  background: #ffffff;
  color: var(--teal-dark);
  cursor: pointer;
  padding: 0.45rem 0.8rem;
  font: inherit;
  font-size: 0.82rem;
  font-weight: 900;
}

.quick-times button:hover,
.quick-times button:focus-visible {
  background: rgba(3, 151, 164, 0.1);
  outline: none;
}

.quiz-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.primary-button,
.secondary-button {
  min-height: 2.85rem;
  border-radius: 999px;
  padding: 0 1.2rem;
  cursor: pointer;
  font-weight: 900;
}

.primary-button {
  border: 0;
  background: linear-gradient(135deg, var(--teal), var(--teal-dark));
  color: #ffffff;
}

.secondary-button {
  border: 1px solid rgba(5, 107, 117, 0.18);
  background: #ffffff;
  color: var(--teal-dark);
}

.quiz-feedback {
  min-height: 1.5rem;
  margin: 0;
  font-weight: 900;
}

.quiz-feedback.is-correct {
  color: #15803d;
}

.quiz-feedback.is-incorrect {
  color: #b45309;
}

.hint-box {
  margin-top: 1.5rem;
  border: 1px solid rgba(5, 107, 117, 0.12);
  border-radius: 1.3rem;
  background: rgba(238, 249, 250, 0.82);
  padding: 1rem;
}

.hint-box strong {
  color: var(--teal-dark);
}

.hint-box p {
  margin: 0.35rem 0 0;
  color: #566678;
  line-height: 1.6;
}

.explain-box {
  display: grid;
  gap: 0.75rem;
  margin-top: 1rem;
}

.explanation-text {
  min-height: 1.5rem;
  margin: 0;
  border-radius: 1rem;
  color: #7a4b00;
  font-size: 0.95rem;
  font-weight: 750;
  line-height: 1.6;
}

.explanation-text:not(:empty) {
  border: 1px solid rgba(245, 158, 11, 0.22);
  background: rgba(255, 247, 219, 0.78);
  padding: 0.9rem 1rem;
}

.is-hidden {
  display: none;
}

.clock-number {
  fill: var(--text);
  font-size: 22px;
  font-weight: 900;
  text-anchor: middle;
  dominant-baseline: middle;
}

@media (max-width: 760px) {
  .mode-tabs,
  .content-grid {
    grid-template-columns: 1fr;
  }

  .mode-tabs {
    gap: 0.35rem;
  }

  .practice-card {
    border-radius: 1.5rem;
  }

  .answer-text {
    min-height: 3.25rem;
    font-size: clamp(1.5rem, 8vw, 2.2rem);
  }
}