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

:root {
  --bg: #0f172a;
  --surface: #1e293b;
  --surface2: #334155;
  --text: #f8fafc;
  --muted: #94a3b8;
  --accent: #2dd4bf;
  --accent-dim: #115e59;
  --danger: #f87171;
  --radius: 16px;
  --radius-sm: 12px;
  --font: system-ui, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --safe-b: env(safe-area-inset-bottom, 0px);
  --safe-t: env(safe-area-inset-top, 0px);
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100dvh;
  font-family: var(--font);
  background: linear-gradient(165deg, #0f172a 0%, #134e4a 45%, #0f172a 100%);
  color: var(--text);
  padding: calc(12px + var(--safe-t)) 16px calc(24px + var(--safe-b));
  line-height: 1.5;
}

#app {
  max-width: 480px;
  margin: 0 auto;
}

.header {
  text-align: center;
  margin-bottom: 1.25rem;
}

.header__title {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.header__sub {
  margin: 0.35rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.screen[hidden],
.card[hidden],
.lesson[hidden] {
  display: none !important;
}

.card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.1rem 1.15rem;
  margin-bottom: 1rem;
  border: 1px solid rgba(255, 255, 255, 0.06);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
}

.card__h {
  margin: 0 0 0.75rem;
  font-size: 1.1rem;
}

.card__h--sm {
  font-size: 1rem;
  margin-bottom: 0.6rem;
}

.muted {
  color: var(--muted);
  font-size: 0.92rem;
}

.small {
  font-size: 0.82rem;
  margin: 0.25rem 0 0;
}

.lead {
  margin: 0 0 0.5rem;
  font-size: 1.05rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin: 1rem 0;
}

.field span:first-child {
  font-size: 0.88rem;
  color: var(--muted);
}

.field input[type="date"] {
  font-size: 1.1rem;
  padding: 0.75rem 0.85rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--surface2);
  background: #0f172a;
  color: var(--text);
  min-height: 48px;
}

.field--inline {
  flex-direction: row;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.field--inline input[type="range"] {
  flex: 1;
  min-width: 120px;
  accent-color: var(--accent);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  min-height: 48px;
  padding: 0 1.15rem;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-family: inherit;
  -webkit-tap-highlight-color: transparent;
}

.btn--primary {
  background: linear-gradient(135deg, var(--accent) 0%, #14b8a6 100%);
  color: #042f2e;
  width: 100%;
}

.btn--primary:active {
  transform: scale(0.98);
}

.btn--ghost {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent-dim);
}

.btn--small {
  min-height: 40px;
  padding: 0 0.75rem;
  font-size: 0.88rem;
  width: auto;
}

.btn--round {
  width: 52px;
  min-width: 52px;
  padding: 0;
  border-radius: 50%;
  background: var(--surface2);
  color: var(--text);
  font-size: 1.25rem;
}

.status {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.status__row {
  font-size: 1rem;
}

.principles {
  margin: 0;
  padding-left: 1.2rem;
  color: var(--muted);
}

.principles li {
  margin-bottom: 0.35rem;
}

.lesson__head {
  text-align: center;
}

.lesson__badge {
  margin: 0;
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.lesson__title {
  margin: 0.35rem 0 0;
  font-size: 1.35rem;
  line-height: 1.25;
}

.vocab-section__bar {
  margin-bottom: 0.75rem;
}

.vocab-section__h {
  margin: 0;
  font-size: 1.05rem;
}

.slide {
  position: relative;
  min-height: 220px;
  border-radius: var(--radius);
  background: linear-gradient(145deg, var(--surface2) 0%, #0f172a 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.25rem 1rem;
  touch-action: pan-y;
  outline: none;
}

.slide:focus-visible {
  box-shadow: 0 0 0 3px var(--accent);
}

.slide__visual {
  font-size: 4.5rem;
  line-height: 1;
  margin-bottom: 0.5rem;
  user-select: none;
}

.slide__word {
  margin: 0;
  font-size: clamp(1.5rem, 6vw, 2rem);
  font-weight: 700;
  text-align: center;
  word-break: break-word;
}

.slide__idx {
  margin: 0.65rem 0 0;
  font-size: 0.8rem;
  color: var(--muted);
}

.slide-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-top: 1rem;
}

.slide-options {
  margin-top: 1rem;
  padding-top: 0.85rem;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.check {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.95rem;
  cursor: pointer;
}

.check input {
  width: 20px;
  height: 20px;
  accent-color: var(--accent);
}

.steps {
  margin: 0;
  padding-left: 1.2rem;
  color: #e2e8f0;
}

.steps li {
  margin-bottom: 0.45rem;
}

.video-hint {
  margin: 1rem 0 0;
  padding: 0.85rem 0 0;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.video-hint__title {
  margin: 0 0 0.65rem;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--muted);
}

.video-hint__links {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.video-hint__links a {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.65rem 1rem;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  color: #042f2e;
  background: linear-gradient(135deg, var(--accent) 0%, #14b8a6 100%);
  border-radius: var(--radius-sm);
  text-align: center;
  line-height: 1.3;
  -webkit-tap-highlight-color: transparent;
}

.video-hint__links a:active {
  transform: scale(0.98);
  opacity: 0.95;
}

.daily {
  margin: 1rem 0 0;
  padding: 0.85rem;
  background: rgba(45, 212, 191, 0.1);
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--accent);
  font-size: 0.95rem;
}

@media (min-width: 400px) {
  .slide {
    min-height: 260px;
  }

  .slide__visual {
    font-size: 5rem;
  }
}