/* Vocab Studio — design system (iOS look, light + dark).
   Screen-specific rules live in css/screens/*.css. */

/* ---------- Tokens ---------- */
:root {
  color-scheme: light;
  --accent: #5856d6;
  --accent-press: #4a48c4;
  --accent-tint: rgba(88, 86, 214, 0.12);
  /* Fills that carry white text, and accent text on an accent tint: the
     plain --accent is too light for either in dark mode. */
  --accent-fill: #5856d6;
  --accent-on-tint: #4a48c4;
  --on-fill: #ffffff;
  --green-fill: #1f7a33;
  --red-fill: #d70015;
  /* Status colours as text (the plain ones are for icons, borders, fills). */
  --green-text: #1a7330;
  --orange-text: #b83000;
  --red-text: #c4001a;
  --blue-text: #0040dd;
  --purple-text: #8944ab;
  --teal-text: #007080;
  --orange-2: #ffb340;
  --green-2: #5ee08a;
  --blue: #007aff;
  --green: #34c759;
  --red: #ff3b30;
  --orange: #ff9500;
  --yellow: #ffcc00;
  --purple: #af52de;
  --teal: #30b0c7;
  --pink: #ff2d55;
  --gray: #8e8e93;
  --green-tint: rgba(52, 199, 89, 0.14);
  --red-tint: rgba(255, 59, 48, 0.12);
  --orange-tint: rgba(255, 149, 0, 0.14);
  --blue-tint: rgba(0, 122, 255, 0.12);
  --purple-tint: rgba(175, 82, 222, 0.12);
  --teal-tint: rgba(48, 176, 199, 0.14);
  --gray-tint: rgba(142, 142, 147, 0.14);

  --bg: #f2f2f7;
  --card: #ffffff;
  --card-2: #f2f2f7;
  --elevated: #ffffff;
  --label: #000000;
  --label-2: rgba(60, 60, 67, 0.76); /* 5.0:1 on --bg, 4.6:1 in a gray badge (iOS: 0.6, 3.3:1) */
  --label-3: rgba(60, 60, 67, 0.3);
  --separator: rgba(60, 60, 67, 0.2);
  --fill: rgba(118, 118, 128, 0.12);
  --fill-2: rgba(118, 118, 128, 0.18);
  --press: rgba(0, 0, 0, 0.06);
  --material: rgba(249, 249, 249, 0.82);
  --material-thick: rgba(242, 242, 247, 0.92);
  --scrim: rgba(0, 0, 0, 0.32);
  --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.04), 0 6px 20px rgba(0, 0, 0, 0.05);
  --shadow-pop: 0 10px 40px rgba(0, 0, 0, 0.18);
  --shadow-toast: 0 6px 24px rgba(0, 0, 0, 0.16);
  --thumb: #ffffff;

  --font: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Segoe UI', Roboto, Inter, 'Helvetica Neue', Arial, sans-serif;
  --font-rounded: ui-rounded, -apple-system, 'SF Pro Rounded', BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: ui-monospace, 'SF Mono', Menlo, Consolas, monospace;

  --ease: cubic-bezier(0.32, 0.72, 0, 1);
  --ease-out: cubic-bezier(0.2, 0.8, 0.2, 1);
  --dur: 380ms;

  --safe-top: env(safe-area-inset-top, 0px);
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --safe-left: env(safe-area-inset-left, 0px);
  --safe-right: env(safe-area-inset-right, 0px);
  --nav-h: 44px;
  --tab-h: 50px;
  --gutter: 16px;
  --radius: 12px;
  --radius-lg: 14px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    color-scheme: dark;
    --accent: #7d7aff;
    --accent-press: #4f4dd4;
    --accent-tint: rgba(125, 122, 255, 0.2);
    --accent-fill: #5e5ce6;
    --accent-on-tint: #a5a3ff;
    --on-fill: #ffffff;
    --green-fill: #1f7a33;
    --red-fill: #d70015;
    --green-text: #30d158;
    --orange-text: #ff9f0a;
    --red-text: #ff6961;
    --blue-text: #409cff;
    --purple-text: #da8fff;
    --teal-text: #40c8e0;
    --orange-2: #ffc35a;
    --green-2: #4ee07a;
    --blue: #0a84ff;
    --green: #30d158;
    --red: #ff453a;
    --orange: #ff9f0a;
    --yellow: #ffd60a;
    --purple: #bf5af2;
    --teal: #40c8e0;
    --pink: #ff375f;
    --gray: #8e8e93;
    --green-tint: rgba(48, 209, 88, 0.2);
    --red-tint: rgba(255, 69, 58, 0.2);
    --orange-tint: rgba(255, 159, 10, 0.2);
    --blue-tint: rgba(10, 132, 255, 0.22);
    --purple-tint: rgba(191, 90, 242, 0.22);
    --teal-tint: rgba(64, 200, 224, 0.2);
    --gray-tint: rgba(142, 142, 147, 0.24);
    --bg: #000000;
    --card: #1c1c1e;
    --card-2: #2c2c2e;
    --elevated: #2c2c2e;
    --label: #ffffff;
    --label-2: rgba(235, 235, 245, 0.6);
    --label-3: rgba(235, 235, 245, 0.3);
    --separator: rgba(84, 84, 88, 0.6);
    --fill: rgba(118, 118, 128, 0.24);
    --fill-2: rgba(118, 118, 128, 0.32);
    --press: rgba(255, 255, 255, 0.08);
    --material: rgba(22, 22, 24, 0.8);
    --material-thick: rgba(28, 28, 30, 0.92);
    --scrim: rgba(0, 0, 0, 0.5);
    --shadow-card: none;
    --shadow-pop: 0 10px 40px rgba(0, 0, 0, 0.6);
    --shadow-toast: 0 6px 24px rgba(0, 0, 0, 0.5);
    --thumb: #636366;
  }
}

:root[data-theme='dark'] {
  color-scheme: dark;
  --accent: #7d7aff;
  --accent-press: #4f4dd4;
  --accent-tint: rgba(125, 122, 255, 0.2);
  --accent-fill: #5e5ce6;
  --accent-on-tint: #a5a3ff;
  --on-fill: #ffffff;
  --green-fill: #1f7a33;
  --red-fill: #d70015;
  --green-text: #30d158;
  --orange-text: #ff9f0a;
  --red-text: #ff6961;
  --blue-text: #409cff;
  --purple-text: #da8fff;
  --teal-text: #40c8e0;
  --orange-2: #ffc35a;
  --green-2: #4ee07a;
  --blue: #0a84ff;
  --green: #30d158;
  --red: #ff453a;
  --orange: #ff9f0a;
  --yellow: #ffd60a;
  --purple: #bf5af2;
  --teal: #40c8e0;
  --pink: #ff375f;
  --gray: #8e8e93;
  --green-tint: rgba(48, 209, 88, 0.2);
  --red-tint: rgba(255, 69, 58, 0.2);
  --orange-tint: rgba(255, 159, 10, 0.2);
  --blue-tint: rgba(10, 132, 255, 0.22);
  --purple-tint: rgba(191, 90, 242, 0.22);
  --teal-tint: rgba(64, 200, 224, 0.2);
  --gray-tint: rgba(142, 142, 147, 0.24);
  --bg: #000000;
  --card: #1c1c1e;
  --card-2: #2c2c2e;
  --elevated: #2c2c2e;
  --label: #ffffff;
  --label-2: rgba(235, 235, 245, 0.6);
  --label-3: rgba(235, 235, 245, 0.3);
  --separator: rgba(84, 84, 88, 0.6);
  --fill: rgba(118, 118, 128, 0.24);
  --fill-2: rgba(118, 118, 128, 0.32);
  --press: rgba(255, 255, 255, 0.08);
  --material: rgba(22, 22, 24, 0.8);
  --material-thick: rgba(28, 28, 30, 0.92);
  --scrim: rgba(0, 0, 0, 0.5);
  --shadow-card: none;
  --shadow-pop: 0 10px 40px rgba(0, 0, 0, 0.6);
  --shadow-toast: 0 6px 24px rgba(0, 0, 0, 0.5);
  --thumb: #636366;
}

/* Dark sheets use the elevated background (as iOS does), so their edge
   shows on the black page. Groups and cards inside use --card. */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) .sheet {
    --bg: #1c1c1e;
    --card: #2c2c2e;
    /* Lighter grey badges, so their text keeps 4.5:1 on the lighter card. */
    --gray-tint: rgba(142, 142, 147, 0.14);
  }
}

:root[data-theme='dark'] .sheet {
  --bg: #1c1c1e;
  --card: #2c2c2e;
  --gray-tint: rgba(142, 142, 147, 0.14);
}

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

html,
body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  overscroll-behavior: none;
  background: var(--bg);
}

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}

body {
  position: fixed;
  inset: 0;
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--label);
  -webkit-font-smoothing: antialiased;
}

button,
input,
textarea,
select {
  font: inherit;
  color: inherit;
  letter-spacing: inherit;
}

button {
  border: 0;
  background: none;
  padding: 0;
  margin: 0;
  cursor: pointer;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

a {
  color: var(--accent);
  text-decoration: none;
}

input,
textarea {
  caret-color: var(--accent);
}

::selection {
  background: var(--accent-tint);
}

/* Focus rings only for keyboard focus (iPad / desktop); fields draw their own. */
:focus:not(:focus-visible) {
  outline: none;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

input:focus-visible,
textarea:focus-visible {
  outline: none;
}

.row:focus-visible,
.chip:focus-visible {
  outline-offset: -2px;
}

/* Interface text is not selectable (a long press would bring up the iOS
   callout); content such as sentences and passages stays selectable. */
.nav,
.tabbar,
.large-title,
.large-subtitle,
.section-header,
.section-footer,
.footer,
.badge,
.segmented,
.practice-top,
.practice-footer {
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

svg.icon {
  flex: none;
  display: block;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

[hidden] {
  display: none !important;
}

.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* ---------- App frame ---------- */
#app {
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  height: var(--app-h, 100%);
  transform: translate3d(0, var(--app-top, 0px), 0);
  overflow: hidden;
  background: var(--bg);
}

.stack {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.stack.busy {
  pointer-events: none;
}

.screen {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  overflow: hidden;
  contain: layout paint;
  will-change: auto;
}

.screen.modal {
  background: var(--bg);
}

/* dim overlay used by the router during transitions */
/* The moving screen's left edge during push, pop and swipe-back (in dark
   mode the dim on black is invisible, so the hairline carries the edge). */
.stack.busy > .screen:last-child:not(.modal),
.screen.tracking {
  box-shadow: -0.5px 0 0 var(--separator), -10px 0 24px rgba(0, 0, 0, 0.12);
}

.screen > .screen-dim {
  position: absolute;
  inset: 0;
  background: #000;
  opacity: 0;
  pointer-events: none;
  z-index: 50;
}

.scroll {
  flex: 1 1 auto;
  min-height: 0;
  overflow-x: hidden;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior-y: contain;
  padding-left: var(--safe-left);
  padding-right: var(--safe-right);
}

.scroll-inner {
  padding: 0 var(--gutter) 32px;
  max-width: 720px;
  margin: 0 auto;
}

.screen.has-tabbar .scroll-inner {
  padding-bottom: calc(var(--tab-h) + var(--safe-bottom) + 32px);
}

/* ---------- Navigation bar ---------- */
.nav {
  position: relative;
  z-index: 20;
  flex: none;
  padding-top: var(--safe-top);
  padding-left: var(--safe-left);
  padding-right: var(--safe-right);
  background: transparent;
  transition: background-color 200ms linear;
}

.nav::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 0.5px;
  background: var(--separator);
  opacity: 0;
  transition: opacity 200ms linear;
}

.screen.scrolled .nav,
.nav.solid {
  background: var(--material);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
}

.screen.scrolled .nav::after,
.nav.solid::after {
  opacity: 1;
}

.nav-bar,
.sheet-bar {
  position: relative;
  height: var(--nav-h);
  /* Title between two equal sides: it stays centred while there is room and
     never runs into a long back label (each side keeps its own width). */
  display: grid;
  grid-template-columns: minmax(max-content, 1fr) minmax(0, auto) minmax(max-content, 1fr);
  align-items: center;
  column-gap: 6px;
  padding: 0 8px;
}

.nav-side {
  display: flex;
  align-items: center;
  min-width: 44px;
  gap: 2px;
  z-index: 1;
}

.nav-side.right {
  justify-content: flex-end;
}

.nav-title,
.sheet-title {
  min-width: 0;
  text-align: center;
  font-size: 17px;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  pointer-events: none;
  transition: opacity 180ms linear;
}

/* .has-large-title is the screen flag; .large-title is the h1 itself */
.screen.has-large-title .nav-title {
  opacity: 0;
}

.screen.has-large-title.scrolled .nav-title {
  opacity: 1;
}

.nav-back,
.nav-action {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  min-height: 44px;
  min-width: 44px;
  padding: 0 8px;
  color: var(--accent);
  font-size: 17px;
  border-radius: 10px;
  transition: opacity 120ms linear;
}

.nav-back {
  padding-left: 0;
  max-width: 140px;
}

.nav-back span {
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-back svg {
  width: 28px;
  height: 28px;
  stroke-width: 2.4;
}

.nav-action.strong {
  font-weight: 600;
}

.nav-action:disabled {
  color: var(--label-3);
}

.nav-back:active,
.nav-action:active {
  opacity: 0.4;
}

.large-title {
  font-size: 34px;
  line-height: 41px;
  font-weight: 700;
  letter-spacing: 0.01em;
  margin: 2px 0 16px;
  padding-top: 2px;
  overflow-wrap: anywhere;
  /* A long list name stays two lines; the nav bar and Edit list show it all. */
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
  overflow: hidden;
}

.large-subtitle {
  margin: -12px 0 18px;
  color: var(--label-2);
  font-size: 15px;
}

/* ---------- Tab bar ---------- */
.tabbar {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 30;
  display: flex;
  justify-content: space-around;
  padding: 0 var(--safe-right) var(--safe-bottom) var(--safe-left);
  background: var(--material);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
}

.tabbar::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 0.5px;
  background: var(--separator);
}

/* While typing, the keyboard takes the bottom of the screen (as in native apps). */
html.kb-open .tabbar {
  visibility: hidden;
}

html.kb-open .screen.has-tabbar .scroll-inner {
  padding-bottom: 32px;
}

.tab {
  flex: 1;
  max-width: 160px;
  height: var(--tab-h);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  color: var(--gray);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.01em;
}

.tab svg {
  width: 26px;
  height: 26px;
}

.tab.active {
  color: var(--accent);
}

/* The selected tab's symbol is filled, as in iOS (closed shapes only). */
.tab.active svg {
  fill: currentColor;
  fill-opacity: 0.22;
}

.tab.active .icon-sun path,
.tab.active .icon-books path:not(:first-child) {
  fill: none;
}

.tab .tab-badge {
  position: absolute;
  margin-left: 26px;
  margin-top: -20px;
  min-width: 18px;
  height: 18px;
  padding: 0 5px;
  border-radius: 9px;
  background: var(--red-fill);
  color: var(--on-fill);
  font-size: 12px;
  line-height: 18px;
  font-weight: 600;
  text-align: center;
}

/* ---------- Footer (thumb zone actions) ---------- */
.footer {
  flex: none;
  position: relative;
  z-index: 20;
  padding: 10px calc(var(--gutter) + var(--safe-right)) calc(10px + var(--safe-bottom)) calc(var(--gutter) + var(--safe-left));
  background: var(--material-thick);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
}

.footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 0.5px;
  background: var(--separator);
}

.footer.clear {
  background: transparent;
  -webkit-backdrop-filter: none;
  backdrop-filter: none;
}

.footer.clear::before {
  display: none;
}

.footer-row {
  display: flex;
  gap: 10px;
  max-width: 720px;
  margin: 0 auto;
}

.footer-row > * {
  flex: 1;
}

html.kb-open .footer {
  padding-bottom: 10px;
}

/* ---------- Buttons ---------- */
.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 18px;
  border-radius: 12px;
  font-size: 17px;
  font-weight: 600;
  line-height: 1.1;
  text-align: center;
  white-space: nowrap;
  transition: transform 140ms var(--ease-out), opacity 140ms linear, background-color 160ms linear, color 160ms linear;
}

.btn svg {
  width: 20px;
  height: 20px;
}

.btn.large {
  min-height: 52px;
  border-radius: 14px;
  padding: 0 22px;
}

.btn.small {
  min-height: 34px;
  padding: 0 14px;
  border-radius: 17px;
  font-size: 15px;
}

.btn.block {
  display: flex;
  width: 100%;
}

.btn.primary {
  background: var(--accent-fill);
  color: var(--on-fill);
}

.btn.tinted {
  background: var(--accent-tint);
  color: var(--accent-on-tint);
}

.btn.secondary {
  background: var(--fill);
  color: var(--label);
}

.btn.plain {
  background: transparent;
  color: var(--accent);
  font-weight: 500;
}

.btn.destructive {
  background: var(--red-tint);
  color: var(--red-text);
}

.btn.success {
  background: var(--green-fill);
  color: var(--on-fill);
}

.btn.danger {
  background: var(--red-fill);
  color: var(--on-fill);
}

.btn:active:not(:disabled) {
  transform: scale(0.97);
  opacity: 0.82;
}

.btn:disabled {
  opacity: 0.38;
  cursor: default;
}

.btn.primary:disabled {
  background: var(--fill-2);
  color: var(--label-2);
  opacity: 1;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 22px;
  color: var(--accent);
  transition: transform 140ms var(--ease-out), opacity 140ms linear, background-color 160ms linear;
}

.icon-btn.filled {
  background: var(--accent-tint);
}

.icon-btn.gray {
  color: var(--label-2);
  background: var(--fill);
}

.icon-btn:active {
  transform: scale(0.92);
  opacity: 0.6;
}

.icon-btn svg {
  width: 22px;
  height: 22px;
}

@media (hover: hover) {
  .btn.primary:hover:not(:disabled) {
    background: var(--accent-press);
  }
  .row.tappable:hover {
    background: var(--press);
  }
}

/* ---------- Grouped sections and rows ---------- */
.section {
  margin: 0 0 28px;
}

.section-header {
  padding: 0 16px 7px;
  color: var(--label-2);
  font-size: 13px;
  line-height: 18px;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

.section-header.prominent {
  padding: 0 4px 8px;
  color: var(--label);
  font-size: 22px;
  line-height: 28px;
  font-weight: 700;
  text-transform: none;
  letter-spacing: 0;
}

.section-footer {
  padding: 7px 16px 0;
  color: var(--label-2);
  font-size: 13px;
  line-height: 18px;
}

.group {
  background: var(--card);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.row {
  position: relative;
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 44px;
  padding: 10px 16px;
  width: 100%;
  text-align: left;
  background: transparent;
  transition: background-color 120ms linear;
}

.row.tappable {
  cursor: pointer;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

.row.tappable:active {
  background: var(--press);
  transition: none;
}

.row + .row::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  left: 16px;
  height: 0.5px;
  background: var(--separator);
}

.row.with-icon + .row::before,
.row + .row.with-icon::before {
  left: 58px;
}

.row-icon {
  flex: none;
  width: 30px;
  height: 30px;
  border-radius: 7px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--on-fill);
  background: var(--accent);
}

.row-icon svg {
  width: 18px;
  height: 18px;
  stroke-width: 2.2;
}

.row-main {
  flex: 1;
  min-width: 0;
}

.row-title {
  font-size: 17px;
  line-height: 22px;
  overflow-wrap: anywhere;
}

.row-subtitle {
  margin-top: 1px;
  font-size: 15px;
  line-height: 20px;
  color: var(--label-2);
  overflow-wrap: anywhere;
}

.row-detail {
  flex: none;
  max-width: 45%;
  color: var(--label-2);
  font-size: 17px;
  text-align: right;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.row-chevron {
  flex: none;
  color: var(--label-3);
  margin-right: -6px;
}

.row-chevron svg {
  width: 18px;
  height: 18px;
  stroke-width: 2.6;
}

.row.destructive .row-title {
  color: var(--red);
}

.row.accent .row-title {
  color: var(--accent);
}

.row.centered {
  justify-content: center;
  text-align: center;
}

/* ---------- Cards ---------- */
.card {
  background: var(--card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  padding: 16px;
}

button.card {
  display: block;
  width: 100%;
  text-align: left;
}

.card.tappable {
  cursor: pointer;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
  transition: transform 160ms var(--ease-out), opacity 160ms linear;
}

.card.tappable:active {
  transform: scale(0.98);
  opacity: 0.9;
}

/* ---------- Segmented control ---------- */
.segmented {
  position: relative;
  display: flex;
  padding: 2px;
  border-radius: 9px;
  background: var(--fill);
  -webkit-user-select: none;
  user-select: none;
}

.segmented-thumb {
  position: absolute;
  top: 2px;
  bottom: 2px;
  left: 2px;
  border-radius: 7px;
  background: var(--thumb);
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.12), 0 3px 1px rgba(0, 0, 0, 0.04);
  transition: transform 260ms var(--ease);
  will-change: transform;
}

.segmented button {
  position: relative;
  flex: 1;
  min-width: 0;
  min-height: 32px;
  padding: 0 8px;
  font-size: 13px;
  font-weight: 500;
  border-radius: 7px;
  color: var(--label);
}

/* The ellipsis lives on the label: overflow on the button would clip the
   44pt hit area below. */
.segmented-label {
  display: block;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.segmented button[aria-pressed='true'] {
  font-weight: 600;
}

/* larger tap area while keeping the visual height */
.segmented button::after {
  content: '';
  position: absolute;
  inset: -6px 0;
}

/* ---------- Switch ---------- */
.switch {
  position: relative;
  flex: none;
  width: 51px;
  height: 31px;
  border-radius: 16px;
  background: var(--fill-2);
  transition: background-color 220ms linear;
}

/* 59×45 hit area (::after is the thumb) */
.switch::before {
  content: '';
  position: absolute;
  inset: -7px -4px;
}

.switch::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 27px;
  height: 27px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.15), 0 3px 1px rgba(0, 0, 0, 0.06);
  transition: transform 260ms var(--ease);
}

.switch[aria-checked='true'] {
  background: var(--green);
}

.switch[aria-checked='true']::after {
  transform: translateX(20px);
}

/* ---------- Slider ---------- */
.slider-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
}

.slider-wrap input[type='range'] {
  flex: 1;
  height: 44px;
  margin: 0;
  accent-color: var(--accent);
  background: transparent;
}

.slider-value {
  flex: none;
  min-width: 52px;
  text-align: right;
  color: var(--label-2);
  font-variant-numeric: tabular-nums;
}

/* ---------- Text inputs ---------- */
.field,
.textarea {
  display: block;
  width: 100%;
  min-height: 44px;
  padding: 11px 14px;
  border: 0;
  border-radius: 12px;
  background: var(--fill);
  color: var(--label);
  font-size: 17px;
  line-height: 22px;
  outline: none;
  -webkit-appearance: none;
  appearance: none;
  transition: box-shadow 160ms linear, background-color 160ms linear;
}

.field::placeholder,
.textarea::placeholder {
  color: var(--label-3);
}

.field:focus,
.textarea:focus {
  box-shadow: 0 0 0 2px var(--accent);
}

.textarea {
  resize: none;
  min-height: 120px;
}

.field.answer {
  min-height: 54px;
  font-size: 20px;
  text-align: center;
  border-radius: 14px;
  background: var(--card);
  box-shadow: inset 0 0 0 1px var(--separator);
}

.field.answer:focus {
  box-shadow: inset 0 0 0 2px var(--accent);
}

.field.is-right {
  box-shadow: inset 0 0 0 2px var(--green) !important;
  background: var(--green-tint);
}

.field.is-wrong {
  box-shadow: inset 0 0 0 2px var(--red) !important;
  background: var(--red-tint);
}

.field.is-close {
  box-shadow: inset 0 0 0 2px var(--orange) !important;
  background: var(--orange-tint);
}

.field:read-only {
  cursor: default;
}

.group .field,
.group .textarea {
  background: transparent;
  border-radius: 0;
}

.group .field:focus,
.group .textarea:focus {
  box-shadow: none;
}

/* ---------- Chips and badges ---------- */
.chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 16px;
  border-radius: 22px;
  background: var(--card);
  color: var(--label);
  font-size: 17px;
  font-weight: 500;
  box-shadow: inset 0 0 0 1px var(--separator), 0 1px 2px rgba(0, 0, 0, 0.04);
  transition: transform 140ms var(--ease-out), background-color 160ms linear, color 160ms linear, opacity 200ms linear, box-shadow 160ms linear;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

.chip:active:not(:disabled) {
  transform: scale(0.95);
}

.chip.selected {
  background: var(--accent-fill);
  color: var(--on-fill);
  box-shadow: none;
}

.chip.right {
  background: var(--green-fill);
  color: var(--on-fill);
  box-shadow: none;
}

.chip.wrong {
  background: var(--red-fill);
  color: var(--on-fill);
  box-shadow: none;
}

.chip:disabled,
.chip.dim {
  opacity: 0.35;
}

.badge {
  display: inline-flex;
  align-items: center;
  height: 22px;
  padding: 0 8px;
  border-radius: 11px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0;
  white-space: nowrap;
  background: var(--gray-tint);
  color: var(--label-2);
}

.badge.accent { background: var(--accent-tint); color: var(--accent-on-tint); }
.badge.blue { background: var(--blue-tint); color: var(--blue-text); }
.badge.green { background: var(--green-tint); color: var(--green-text); }
.badge.red { background: var(--red-tint); color: var(--red-text); }
.badge.orange { background: var(--orange-tint); color: var(--orange-text); }
.badge.purple { background: var(--purple-tint); color: var(--purple-text); }
.badge.teal { background: var(--teal-tint); color: var(--teal-text); }

/* ---------- Progress ---------- */
.progress {
  position: relative;
  height: 4px;
  border-radius: 2px;
  background: var(--fill);
  overflow: hidden;
}

.progress-fill {
  position: absolute;
  inset: 0;
  border-radius: 2px;
  background: var(--accent);
  transform-origin: left center;
  transform: scaleX(0);
  transition: transform 420ms var(--ease);
}

.ring {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
}

.ring svg {
  transform: rotate(-90deg);
}

.ring circle {
  fill: none;
  stroke-linecap: round;
}

.ring .ring-track {
  stroke: var(--fill);
}

.ring .ring-value {
  stroke: var(--accent);
  transition: stroke-dashoffset 700ms var(--ease);
}

.ring .ring-label {
  position: absolute;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

/* ---------- Empty state ---------- */
.empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 48px 24px;
  gap: 10px;
}

.empty-icon {
  width: 64px;
  height: 64px;
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  background: var(--accent-tint);
  margin-bottom: 6px;
}

.empty-icon svg {
  width: 32px;
  height: 32px;
}

.empty-title {
  font-size: 22px;
  font-weight: 700;
}

.empty-message {
  color: var(--label-2);
  font-size: 15px;
  line-height: 20px;
  max-width: 320px;
}

.empty .btn {
  margin-top: 10px;
}

/* ---------- Overlays: sheet, alert, action sheet, toast ---------- */
/* Overlays follow the visual viewport like #app, so the iOS keyboard never
   covers a sheet's fields. */
.overlay {
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  height: var(--app-h, 100%);
  transform: translate3d(0, var(--app-top, 0px), 0);
  z-index: 1000;
}

.overlay-scrim {
  position: absolute;
  inset: 0;
  background: var(--scrim);
  opacity: 0;
  transition: opacity 300ms linear;
}

.overlay.open .overlay-scrim {
  opacity: 1;
}

.sheet {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  max-height: calc(100% - var(--safe-top) - 24px);
  display: flex;
  flex-direction: column;
  background: var(--bg);
  border-radius: 14px 14px 0 0;
  box-shadow: var(--shadow-pop);
  transform: translate3d(0, 100%, 0);
  transition: transform 420ms var(--ease);
  will-change: transform;
}

.overlay.open .sheet {
  transform: translate3d(0, 0, 0);
}

.sheet.dragging {
  transition: none;
}

.sheet-head {
  flex: none;
  position: relative;
  padding: 6px 8px 0;
  touch-action: none;
}

.sheet-grabber {
  width: 36px;
  height: 5px;
  margin: 0 auto 4px;
  border-radius: 3px;
  background: var(--label-3);
}

.sheet-bar {
  padding: 0;
}

.sheet-title {
  font-size: 17px;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  pointer-events: none;
}

.sheet-body {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior: contain;
  padding: 8px var(--gutter) calc(24px + var(--safe-bottom));
}

.alert-wrap {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.alert {
  width: 270px;
  max-width: 100%;
  border-radius: 14px;
  overflow: hidden;
  background: var(--material-thick);
  -webkit-backdrop-filter: saturate(180%) blur(30px);
  backdrop-filter: saturate(180%) blur(30px);
  text-align: center;
  opacity: 0;
  transform: scale(1.12);
  transition: transform 260ms var(--ease), opacity 200ms linear;
}

.overlay.open .alert {
  opacity: 1;
  transform: scale(1);
}

.alert-text {
  padding: 19px 16px 18px;
}

.alert-title {
  font-size: 17px;
  font-weight: 600;
  line-height: 22px;
}

.alert-message {
  margin-top: 3px;
  font-size: 13px;
  line-height: 17px;
}

.alert-actions {
  display: flex;
  border-top: 0.5px solid var(--separator);
}

.alert-actions.vertical {
  flex-direction: column;
}

.alert-actions button {
  flex: 1;
  min-height: 44px;
  font-size: 17px;
  color: var(--accent);
}

.alert-actions button + button {
  border-left: 0.5px solid var(--separator);
}

.alert-actions.vertical button + button {
  border-left: 0;
  border-top: 0.5px solid var(--separator);
}

.alert-actions button.cancel {
  font-weight: 600;
}

.alert-actions button.destructive {
  color: var(--red-text);
}

.alert-actions button:active {
  background: var(--press);
}

.action-sheet {
  position: absolute;
  left: 8px;
  right: 8px;
  bottom: calc(8px + var(--safe-bottom));
  max-width: 520px;
  margin: 0 auto;
  transform: translate3d(0, calc(100% + 40px), 0);
  transition: transform 380ms var(--ease);
}

.overlay.open .action-sheet {
  transform: translate3d(0, 0, 0);
}

.action-group {
  border-radius: 14px;
  overflow: hidden;
  background: var(--material-thick);
  -webkit-backdrop-filter: saturate(180%) blur(30px);
  backdrop-filter: saturate(180%) blur(30px);
}

.action-group + .action-group {
  margin-top: 8px;
}

.action-head {
  padding: 14px 16px;
  text-align: center;
  color: var(--label-2);
  font-size: 13px;
  line-height: 18px;
  border-bottom: 0.5px solid var(--separator);
}

.action-head strong {
  display: block;
  font-weight: 600;
}

.action-group button {
  display: block;
  width: 100%;
  min-height: 57px;
  font-size: 20px;
  color: var(--accent);
}

.action-group button + button {
  border-top: 0.5px solid var(--separator);
}

.action-group button.destructive {
  color: var(--red-text);
}

.action-group button.cancel {
  font-weight: 600;
  background: var(--elevated);
}

.action-group button:active {
  background: var(--press);
}

/* Below the nav bar, so a toast never hides Back or the title. While a sheet
   is open, toast() moves the host below the sheet's header. */
.toast-host {
  position: fixed;
  left: 0;
  right: 0;
  top: calc(var(--safe-top) + var(--nav-h) + 6px);
  z-index: 2000;
  display: flex;
  justify-content: center;
  pointer-events: none;
}

.toast {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  max-width: calc(100% - 32px);
  min-height: 44px;
  padding: 10px 18px;
  border-radius: 22px;
  background: var(--elevated);
  box-shadow: var(--shadow-toast);
  font-size: 15px;
  font-weight: 600;
  opacity: 0;
  transform: translate3d(0, -24px, 0) scale(0.96);
  transition: transform 360ms var(--ease), opacity 240ms linear;
  /* Taps go through to what is underneath; only the action button takes them. */
  pointer-events: none;
}

.toast.show {
  opacity: 1;
  transform: translate3d(0, 0, 0) scale(1);
}

.toast svg {
  width: 20px;
  height: 20px;
}

.toast.green svg { color: var(--green); }
.toast.red svg { color: var(--red); }
.toast.accent svg { color: var(--accent); }

/* 44pt tall hit area without making the pill taller */
.toast button {
  flex: none;
  min-height: 44px;
  margin: -10px -12px -10px 0;
  padding: 0 12px;
  color: var(--accent);
  font-weight: 600;
  pointer-events: auto;
}

/* ---------- Text helpers ---------- */
.muted { color: var(--label-2); }
.faint { color: var(--label-3); }
.small { font-size: 15px; line-height: 20px; }
.footnote { font-size: 13px; line-height: 18px; }
.headline { font-size: 17px; font-weight: 600; }
.title-2 { font-size: 22px; line-height: 28px; font-weight: 700; }
.title-3 { font-size: 20px; line-height: 25px; font-weight: 600; }
.ipa { font-family: var(--font); color: var(--label-2); font-size: 15px; letter-spacing: 0; }
.tabular { font-variant-numeric: tabular-nums; }
.stack-v { display: flex; flex-direction: column; gap: 12px; }
.stack-h { display: flex; align-items: center; gap: 8px; }
.wrap { flex-wrap: wrap; }
.grow { flex: 1; min-width: 0; }
.spacer { height: 16px; }

/* ---------- Motion preferences ---------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 1ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 1ms !important;
  }
}

/* ---------- Boot splash ---------- */
.boot {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  z-index: 100;
  transition: opacity 240ms linear;
}

.boot img {
  border-radius: 20px;
}

.boot.gone {
  opacity: 0;
  pointer-events: none;
}