:root {
  --bg: #f4f7f9;
  --surface: #ffffff;
  --surface-soft: #eef3f5;
  --text: #10212b;
  --muted: #5f7084;
  --border: #dce4e8;
  --primary: #164e63;
  --primary-strong: #103e50;
  --primary-soft: #e7f0f3;
  --teal: #0f766e;
  --again: #fff0f1;
  --again-border: #f3c7cc;
  --hard: #fff7e8;
  --hard-border: #efd39e;
  --good: #edf8f1;
  --good-border: #bddfc8;
  --easy: #edf5ff;
  --easy-border: #c1d7f0;
  --shadow-soft: 0 12px 34px rgba(16, 33, 43, .07);
  --shadow-card: 0 18px 48px rgba(22, 78, 99, .1);
}

* { box-sizing: border-box; }

html { color-scheme: light; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  padding: max(22px, env(safe-area-inset-top)) max(18px, env(safe-area-inset-right)) max(38px, env(safe-area-inset-bottom)) max(18px, env(safe-area-inset-left));
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
}

main {
  width: 100%;
  max-width: 920px;
  margin: 0 auto;
}

.app-header {
  display: flex;
  width: max-content;
  max-width: 100%;
  margin: 0 auto 18px;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.brand-mark {
  width: 52px;
  height: 52px;
  flex: 0 0 auto;
  border-radius: 12px;
  box-shadow: 0 7px 18px rgba(22, 78, 99, .16);
}

.brand-copy { min-width: 0; }

h1 {
  margin: 0;
  color: var(--primary);
  font-size: clamp(2rem, 4.5vw, 2.65rem);
  font-weight: 850;
  line-height: 1;
  letter-spacing: -.04em;
}

h2 {
  margin: 0;
  color: var(--text);
  font-size: 1.02rem;
  font-weight: 800;
  letter-spacing: -.01em;
}

.subtitle {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: .94rem;
  font-weight: 600;
  line-height: 1.25;
}

.toolbar {
  margin-bottom: 18px;
  padding: 17px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow-soft);
  transition: padding .16s ease, border-radius .16s ease;
}

.toolbar-heading {
  display: flex;
  min-width: 0;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.toolbar-title { min-width: 0; }

.collapsed-summary {
  display: none;
  margin: 0;
  overflow: hidden;
  color: var(--text);
  font-size: .9rem;
  font-weight: 750;
  line-height: 1.3;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.primary-filters,
.secondary-filters {
  display: grid;
  gap: 13px;
}

.primary-filters {
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  margin-top: 15px;
}

.secondary-filters {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  padding-top: 13px;
}

.field {
  display: grid;
  min-width: 0;
  gap: 6px;
}

label {
  color: #334b57;
  font-size: .84rem;
  font-weight: 750;
}

.field-prominent label { color: var(--primary); }

select,
button {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
  color: var(--text);
  padding: 10px 12px;
  font: inherit;
}

select {
  font-size: .96rem;
  font-weight: 600;
}

button {
  font-weight: 750;
  cursor: pointer;
  transition: transform .12s ease, box-shadow .12s ease, border-color .12s ease, background .12s ease;
}

button:hover:not(:disabled) {
  transform: translateY(-1px);
  border-color: #b8c8cf;
  box-shadow: 0 5px 14px rgba(16, 33, 43, .08);
}

button:focus-visible,
select:focus-visible,
summary:focus-visible,
.card:focus-visible {
  outline: 3px solid rgba(15, 118, 110, .32);
  outline-offset: 2px;
}

button:disabled {
  cursor: not-allowed;
  opacity: .48;
}

.quiet-button {
  width: auto;
  min-width: max-content;
  min-height: 38px;
  padding: 7px 11px;
  background: var(--surface-soft);
  color: var(--primary);
  border-color: transparent;
  font-size: .84rem;
}

.more-filters {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

.more-filters summary {
  width: max-content;
  color: var(--primary);
  font-size: .88rem;
  font-weight: 800;
  cursor: pointer;
}

.more-filters summary::marker { color: var(--teal); }

.round-setting {
  width: min(220px, 100%);
  margin-top: 15px;
}

.start-row {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 18px;
  align-items: center;
  margin-top: 17px;
  padding-top: 15px;
  border-top: 1px solid var(--border);
}

.match-copy {
  display: grid;
  gap: 2px;
  color: var(--muted);
  font-size: .84rem;
}

.match-copy strong {
  color: var(--text);
  font-size: .9rem;
}

.start-button {
  width: auto;
  min-width: 158px;
  color: #fff;
  background: var(--primary);
  border-color: var(--primary);
  box-shadow: 0 7px 16px rgba(22, 78, 99, .17);
}

.start-button:hover:not(:disabled) {
  background: var(--primary-strong);
  border-color: var(--primary-strong);
}

.toolbar.is-collapsed {
  padding: 8px 10px 8px 13px;
  border-radius: 13px;
  box-shadow: 0 7px 20px rgba(16, 33, 43, .055);
}

.toolbar.is-collapsed .toolbar-heading { min-height: 38px; }
.toolbar.is-collapsed h2 { display: none; }
.toolbar.is-collapsed #filterBody { display: none; }
.toolbar.is-collapsed .collapsed-summary { display: block; }
.toolbar.is-collapsed .quiet-button { min-height: 34px; padding: 6px 10px; }

.study-shell {
  width: min(100%, 800px);
  margin: 0 auto;
}

.active-filters,
.progress {
  min-height: 18px;
  margin: 0;
  color: var(--muted);
  text-align: center;
  font-weight: 700;
}

.active-filters {
  overflow: hidden;
  font-size: .8rem;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.progress {
  margin: 4px 0 11px;
  color: var(--primary);
  font-size: .9rem;
}

.card {
  display: flex;
  width: 100%;
  height: 520px;
  max-height: 560px;
  padding: 34px 30px;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 22px;
  box-shadow: var(--shadow-card);
  text-align: center;
  cursor: pointer;
}

.card-inner {
  display: grid;
  width: 100%;
  height: 100%;
  min-height: 0;
  grid-template-rows: auto minmax(0, 1fr);
  gap: 12px;
  justify-items: center;
}

.card-label {
  padding: 5px 9px;
  color: var(--primary);
  background: var(--primary-soft);
  border: 1px solid #d5e5ea;
  border-radius: 999px;
  font-size: .66rem;
  font-weight: 850;
  line-height: 1;
  letter-spacing: .09em;
  text-transform: uppercase;
}

.content {
  display: grid;
  width: 100%;
  min-height: 0;
  padding: 8px 11px;
  gap: 16px;
  align-content: center;
  justify-items: center;
  overflow: auto;
  overscroll-behavior: contain;
  scrollbar-gutter: stable;
}

.content[hidden] { display: none !important; }

.front-verb {
  color: var(--text);
  font-size: clamp(2.35rem, 7vw, 4rem);
  font-weight: 850;
  line-height: 1.06;
  letter-spacing: -.035em;
  overflow-wrap: anywhere;
}

.front-tense {
  color: var(--muted);
  font-size: clamp(1.08rem, 3vw, 1.45rem);
  font-weight: 650;
}

.back-heading {
  display: grid;
  gap: 4px;
}

.back-heading strong {
  color: var(--primary);
  font-size: clamp(1.4rem, 4vw, 1.95rem);
  letter-spacing: -.02em;
}

.back-heading span {
  color: var(--muted);
  font-size: .94rem;
  font-weight: 650;
}

.paradigm {
  display: grid;
  width: min(100%, 540px);
  gap: 0;
  text-align: left;
}

.form-row {
  display: grid;
  grid-template-columns: minmax(120px, .9fr) minmax(0, 1.2fr);
  gap: 15px;
  align-items: baseline;
  padding: 8px 10px;
  border-bottom: 1px solid #e8eef1;
}

.form-row:last-child { border-bottom: 0; }

.pronoun {
  color: var(--muted);
  font-size: .92rem;
  font-weight: 600;
}

.conjugation {
  color: var(--text);
  font-size: clamp(1.04rem, 3vw, 1.24rem);
  font-weight: 780;
  overflow-wrap: anywhere;
}

.note {
  max-width: 560px;
  padding: 10px 12px;
  color: #526977;
  background: var(--surface-soft);
  border-left: 3px solid var(--teal);
  border-radius: 7px;
  font-size: .83rem;
  font-style: italic;
  line-height: 1.4;
  text-align: left;
}

.reveal-note {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: .82rem;
  font-weight: 600;
  text-align: center;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-top: 16px;
}

.grade {
  min-height: 52px;
  color: var(--text);
  border-width: 1px;
  box-shadow: none;
}

.grade small {
  display: block;
  margin-top: 2px;
  color: var(--muted);
  font-size: .69rem;
  font-weight: 600;
}

.again { background: var(--again); border-color: var(--again-border); }
.hard { background: var(--hard); border-color: var(--hard-border); }
.good { background: var(--good); border-color: var(--good-border); }
.easy { background: var(--easy); border-color: var(--easy-border); }

.nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 10px;
}

.nav button {
  min-height: 42px;
  color: var(--primary);
  background: transparent;
  border-color: transparent;
  font-size: .88rem;
  box-shadow: none;
}

.nav button:hover:not(:disabled) {
  background: var(--primary-soft);
  border-color: transparent;
  box-shadow: none;
}

.empty {
  min-height: 260px;
  padding: 48px 20px;
  display: grid;
  align-content: center;
  background: var(--surface);
  border: 1px dashed #bfd0d7;
  border-radius: 20px;
  color: var(--muted);
  text-align: center;
  gap: 6px;
}

.empty strong {
  display: block;
  color: var(--text);
  font-size: 1.15rem;
}

.empty .start-button {
  justify-self: center;
  margin-top: 12px;
}

.status {
  min-height: 20px;
  margin: 8px 0 0;
  color: #a3323b;
  font-weight: 650;
  text-align: center;
}

@media (max-width: 620px) {
  body {
    padding: max(14px, env(safe-area-inset-top)) max(12px, env(safe-area-inset-right)) max(28px, env(safe-area-inset-bottom)) max(12px, env(safe-area-inset-left));
  }

  .app-header {
    margin-bottom: 14px;
    gap: 10px;
  }

  .brand-mark {
    width: 44px;
    height: 44px;
    border-radius: 10px;
  }

  h1 { font-size: 1.78rem; }
  .subtitle { margin-top: 3px; font-size: .83rem; }

  .toolbar {
    margin-bottom: 14px;
    padding: 14px;
  }

  .primary-filters,
  .secondary-filters { grid-template-columns: 1fr; }

  .start-row {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .start-button { width: 100%; }

  .empty .start-button { width: min(100%, 260px); }

  .toolbar.is-collapsed {
    margin-bottom: 11px;
    padding: 7px 8px 7px 12px;
  }

  .toolbar.is-collapsed .quiet-button {
    min-height: 34px;
    font-size: .8rem;
  }

  .active-filters { font-size: .75rem; }
  .progress { margin-bottom: 9px; font-size: .84rem; }

  .card {
    height: 470px;
    max-height: none;
    padding: 25px 15px;
    border-radius: 19px;
  }

  .content { padding: 7px 4px; }
  .buttons { grid-template-columns: repeat(2, 1fr); gap: 9px; margin-top: 13px; }
  .grade { min-height: 50px; }
  .nav { margin-top: 7px; }

  .form-row {
    grid-template-columns: minmax(100px, .85fr) minmax(0, 1.15fr);
    gap: 9px;
    padding: 7px 5px;
  }
}

@media (max-width: 360px) {
  .brand-mark { width: 40px; height: 40px; }
  h1 { font-size: 1.62rem; }
  .subtitle { font-size: .78rem; }
  .card { height: 460px; }
}

@media (prefers-reduced-motion: reduce) {
  button,
  .toolbar { transition: none; }
}

/* Practice guidance and round progress */
main { position: relative; }
.attribution {
  position: absolute;
  right: 18px;
  bottom: 4px;
  left: 18px;
  margin: 0;
  color: var(--muted);
  font-size: .72rem;
  font-weight: 600;
  line-height: 1.25;
  text-align: center;
}
.app-header { max-width: calc(100% - 88px); }
body:has(.install-button:not([hidden])) .app-header { max-width: calc(100% - 136px); }
.help-button {
  position: absolute;
  top: 0;
  right: 0;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  padding: 0;
  color: var(--primary);
  background: transparent;
  border-color: transparent;
}
.install-button {
  position: absolute;
  top: 0;
  right: 46px;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  padding: 0;
  color: var(--primary);
  background: transparent;
  border-color: transparent;
}
.install-button svg {
  width: 23px;
  height: 23px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 2;
}
.help-button span {
  display: grid;
  place-items: center;
  width: 25px;
  height: 25px;
  border: 2px solid currentColor;
  border-radius: 50%;
  font-size: 1rem;
  line-height: 1;
}
.grade small { white-space: nowrap; }
.session-progress { margin: 4px 0 11px; }
.session-progress .progress { margin: 0 0 7px; }
#progressBar {
  display: block;
  width: 100%;
  height: 6px;
  overflow: hidden;
  border: 0;
  border-radius: 999px;
  appearance: none;
  background: var(--border);
  color: var(--teal);
}
#progressBar::-webkit-progress-bar { background: var(--border); border-radius: 999px; }
#progressBar::-webkit-progress-value { background: var(--teal); border-radius: 999px; }
#progressBar::-moz-progress-bar { background: var(--teal); border-radius: 999px; }
.help-dialog {
  width: min(560px, calc(100% - 24px));
  max-height: 85vh;
  max-height: 85dvh;
  padding: 0 22px 20px;
  overflow-y: auto;
  overscroll-behavior: contain;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 18px;
  box-shadow: var(--shadow-card);
}
.help-dialog::backdrop { background: rgba(16, 33, 43, .45); }
body:has(.help-dialog[open]) { overflow: hidden; }
.help-heading {
  position: sticky;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 0;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.close-help {
  flex: 0 0 44px;
  width: 44px;
  padding: 0;
  font-size: 1.5rem;
  color: var(--primary);
  background: var(--surface-soft);
  border-color: transparent;
}
.help-dialog h3 { margin: 20px 0 8px; font-size: .98rem; color: var(--primary); }
.help-dialog p, .rating-guide { font-size: .92rem; line-height: 1.55; }
.help-dialog p { margin: 8px 0; }
.rating-guide { margin: 0; }
.rating-guide > div { display: grid; grid-template-columns: 48px minmax(0, 1fr); gap: 12px; padding: 7px 0; }
.rating-guide dt { font-weight: 800; }
.rating-guide dd { margin: 0; }