@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=Manrope:wght@500;600;700;800&display=swap');

:root {
  --ink: #1a2422;
  --muted: #6b7875;
  --paper: #f5f6f5;
  --white: #fff;
  --line: #e4e8e6;
  --green: #43EFD2;
  --green-soft: #eef5f3;
  --green-mid: #2a8f80;
  --green-deep: #1a6b5f;
  --green-hover: #36d4bc;
  --green-glow: rgba(67, 239, 210, 0.16);
  --surface-muted: #eef0ef;
  --shadow: 0 18px 50px rgba(26, 36, 34, 0.07);
  --menu-bg: #ffffff;
  --theme-color: #f5f6f5;
}

[data-theme="dark"] {
  --ink: #e8efed;
  --muted: #8fa09c;
  --paper: #121817;
  --white: #1a2220;
  --line: #2a3532;
  --green: #43EFD2;
  --green-soft: #1c2a27;
  --green-mid: #5ec9b8;
  --green-deep: #8ad9cc;
  --green-hover: #5ae0cb;
  --green-glow: rgba(67, 239, 210, 0.14);
  --surface-muted: #222b29;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.35);
  --menu-bg: #1a2220;
  --theme-color: #121817;
}

* { box-sizing: border-box; }
html {
  height: 100%;
  height: 100dvh;
  overflow: hidden;
  scroll-behavior: smooth;
}
body {
  margin: 0;
  height: 100%;
  height: 100dvh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  background: var(--paper);
  color: var(--ink);
  font-family: 'DM Sans', sans-serif;
  -webkit-font-smoothing: antialiased;
}

.site-header {
  width: 100%;
  max-width: 720px;
  padding: 16px 24px 0;
  margin: 0 auto;
  flex-shrink: 0;
}

.topbar {
  min-height: 44px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
  min-width: 0;
}

.app-menu {
  position: relative;
  flex-shrink: 0;
}

.menu-button {
  width: 40px;
  height: 40px;
  border: 0;
  border-radius: 10px;
  background: var(--surface-muted);
  color: var(--ink);
  display: grid;
  place-items: center;
  cursor: pointer;
  font-size: 16px;
  transition: background 0.18s ease, color 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
}

.menu-button:hover {
  background: var(--green-soft);
  color: var(--green-deep);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(26, 36, 34, 0.1);
}

.menu-button:active {
  transform: translateY(0);
  box-shadow: none;
}

.app-menu.open .menu-button {
  background: var(--green-soft);
  color: var(--green-deep);
}

.menu-button:focus-visible {
  outline: 2px solid var(--green);
  outline-offset: 2px;
}

.menu-panel {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 40;
  width: min(240px, calc(100vw - 32px));
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--menu-bg);
  box-shadow:
    0 4px 12px rgba(15, 47, 43, 0.08),
    0 18px 40px rgba(15, 47, 43, 0.14);
  display: flex;
  flex-direction: column;
  gap: 4px;
  animation: menu-in 0.16s ease-out;
}

.menu-panel[hidden] { display: none; }

@keyframes menu-in {
  from { opacity: 0; transform: translateY(-6px) scale(0.98); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.menu-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 44px;
  padding: 8px 10px;
  border-radius: 10px;
  color: var(--ink);
  font: 600 13px/1.3 'DM Sans', sans-serif;
}

.menu-item-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
}

.menu-item-label i {
  width: 1.1em;
  color: var(--green-mid);
  text-align: center;
}

.menu-toggle {
  cursor: pointer;
  user-select: none;
}

.menu-toggle:hover {
  background: var(--surface-muted);
}

.menu-toggle input {
  position: absolute;
  opacity: 0;
  width: 1px;
  height: 1px;
  pointer-events: none;
}

.menu-switch {
  position: relative;
  width: 34px;
  height: 20px;
  border-radius: 999px;
  background: #c5d5d1;
  transition: background 0.18s ease;
  flex-shrink: 0;
}

[data-theme="dark"] .menu-switch {
  background: #2a4a45;
}

.menu-switch::after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(15, 47, 43, 0.22);
  transition: transform 0.18s ease;
}

.menu-toggle input:checked + .menu-switch {
  background: var(--green);
}

.menu-toggle input:checked + .menu-switch::after {
  transform: translateX(14px);
}

.menu-toggle input:focus-visible + .menu-switch {
  outline: 2px solid var(--green);
  outline-offset: 2px;
}

.menu-select {
  flex-direction: column;
  align-items: stretch;
  justify-content: flex-start;
  gap: 8px;
  padding: 10px;
}

.menu-select:hover {
  background: transparent;
}

.menu-select-wrap {
  position: relative;
  display: block;
}

.menu-select select {
  appearance: none;
  -webkit-appearance: none;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface-muted);
  color: var(--ink);
  padding: 11px 36px 11px 12px;
  font: 600 13px/1.2 'DM Sans', sans-serif;
  cursor: pointer;
  transition: border-color 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.menu-select select:hover {
  border-color: color-mix(in srgb, var(--green-mid) 35%, var(--line));
  background: var(--green-soft);
}

.menu-select select:focus,
.menu-select select:focus-visible {
  outline: none;
  border-color: var(--green);
  box-shadow: 0 0 0 3px var(--green-glow);
}

.menu-select-caret {
  position: absolute;
  top: 50%;
  right: 12px;
  transform: translateY(-50%);
  color: var(--green-mid);
  font-size: 12px;
  pointer-events: none;
  transition: transform 0.15s ease, color 0.15s ease;
}

.menu-select select:focus + .menu-select-caret,
.menu-select-wrap:hover .menu-select-caret {
  color: var(--green-deep);
}

.menu-select select option {
  background: var(--menu-bg);
  color: var(--ink);
  font-weight: 600;
}

[data-theme="dark"] .menu-select select {
  background: var(--surface-muted);
}

[data-theme="dark"] .menu-select select:hover {
  background: var(--green-soft);
  border-color: color-mix(in srgb, var(--green-mid) 35%, var(--line));
}

.brand-mark {
  width: 32px;
  height: 32px;
  display: block;
  object-fit: contain;
}

.brand-name {
  font: 700 16px/1 'Manrope', sans-serif;
  letter-spacing: -0.4px;
}

main {
  width: 100%;
  max-width: 720px;
  padding: 0 24px 12px;
  margin: 0 auto;
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  overflow: hidden;
}

.hero {
  padding: 16px 0 12px;
  flex-shrink: 0;
}

.hero h1 {
  font: 800 clamp(30px, 5vw, 42px)/1.12 'Manrope', sans-serif;
  letter-spacing: -1.6px;
  margin: 0;
}

.hero h1 span { color: var(--green-mid); }

.hero-description {
  margin: 12px 0 0;
  font-size: 14px;
  line-height: 1.6;
  color: var(--muted);
}

.practice-card {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: var(--shadow);
  padding: 24px;
  overflow: hidden;
}

.practice-panels {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}


.practice-nav {
  --nav-pad: 5px;
  --nav-gap: 4px;
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--nav-gap);
  margin: 14px 0 0;
  padding: var(--nav-pad);
  background: var(--surface-muted);
  border-radius: 12px;
  isolation: isolate;
}

.practice-nav::before {
  content: "";
  position: absolute;
  z-index: 0;
  top: var(--nav-pad);
  bottom: var(--nav-pad);
  left: var(--nav-pad);
  width: calc((100% - (2 * var(--nav-pad)) - var(--nav-gap)) / 2);
  border-radius: 9px;
  background: var(--white);
  box-shadow: 0 2px 8px rgba(21, 37, 30, 0.12);
  transition: left 0.35s cubic-bezier(0.22, 1, 0.36, 1);
  pointer-events: none;
}

.practice-nav[data-active="word"]::before {
  left: calc(var(--nav-pad) + ((100% - (2 * var(--nav-pad)) - var(--nav-gap)) / 2) + var(--nav-gap));
}

.nav-tab {
  position: relative;
  z-index: 1;
  border: 0;
  background: transparent;
  border-radius: 9px;
  padding: 11px 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  cursor: pointer;
  color: #6d776f;
  font-family: inherit;
  transition: color 0.2s ease, transform 0.18s ease;
}

.nav-tab:hover {
  color: var(--ink);
  transform: translateY(-1px);
}

.nav-tab:hover .tab-icon {
  transform: scale(1.06);
}

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

.nav-tab strong {
  font-size: 13px;
  font-weight: 600;
}

.tab-icon {
  height: 28px;
  width: 28px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  font-size: 14px;
  font-weight: 700;
  flex-shrink: 0;
  transition: transform 0.18s ease;
}

.sentence-icon {
  background: var(--surface-muted);
  color: var(--green-deep);
  font-size: 13px;
}
.word-icon { background: var(--surface-muted); color: var(--muted); font-size: 11px; }

.practice-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.practice-panel[hidden] { display: none !important; }

.exercise {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  margin: 0;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fafbfa;
  overflow: visible;
}

.exercise-heading {
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  border-bottom: 1px solid var(--line);
  flex-shrink: 0;
}

.topic-picker {
  position: relative;
  min-width: 0;
  max-width: min(260px, 58vw);
}

.lesson-label {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
  font-size: 12px;
  font-weight: 600;
  color: #667268;
}

.topic-trigger {
  width: 100%;
  border: 0;
  background: transparent;
  padding: 4px 2px;
  border-radius: 8px;
  cursor: pointer;
  font: inherit;
  color: inherit;
  text-align: left;
  transition: background 0.15s ease, color 0.15s ease;
}

.topic-trigger:hover,
.topic-picker.open .topic-trigger {
  background: var(--surface-muted);
  color: var(--ink);
}

.topic-trigger:focus-visible {
  outline: 2px solid var(--green);
  outline-offset: 2px;
}

.topic-current {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.topic-trigger .fa-caret-down {
  margin-left: auto;
  color: #8a948c;
  font-size: 12px;
  line-height: 1;
  transition: transform 0.2s ease;
}

.topic-picker.open .topic-trigger .fa-caret-down {
  transform: rotate(180deg);
  color: var(--green-mid);
}

.topic-menu {
  position: absolute;
  z-index: 30;
  top: calc(100% + 8px);
  left: 0;
  min-width: max(100%, 260px);
  max-width: min(340px, 88vw);
  max-height: 300px;
  overflow: auto;
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: linear-gradient(180deg, #ffffff 0%, #f3fcfa 100%);
  box-shadow:
    0 4px 12px rgba(15, 47, 43, 0.06),
    0 22px 48px rgba(15, 47, 43, 0.14);
  scrollbar-width: thin;
  scrollbar-color: #8fd9cb transparent;
  animation: topic-menu-in 0.18s ease-out;
}

@keyframes topic-menu-in {
  from {
    opacity: 0;
    transform: translateY(-6px) scale(0.98);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.topic-menu[hidden] { display: none; }

.topic-option {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  border: 0;
  border-radius: 10px;
  background: transparent;
  padding: 11px 12px;
  color: #3f4d43;
  font: 600 12.5px/1.35 'DM Sans', sans-serif;
  text-align: left;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}

.topic-option:hover,
.topic-option:focus-visible {
  background: var(--surface-muted);
  color: var(--ink);
  outline: none;
  transform: translateX(2px);
}

.topic-option.selected {
  background: var(--green-soft);
  color: var(--green-deep);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--green) 35%, var(--line));
}

.topic-option.selected::after {
  content: "\f00c";
  font-family: "Font Awesome 6 Free";
  font-weight: 900;
  margin-left: auto;
  color: var(--green-mid);
  font-size: 11px;
}

.lesson-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--green);
  flex-shrink: 0;
}

.progress-label {
  font-size: 11px;
  letter-spacing: 0.4px;
  font-weight: 700;
  color: #60715f;
}

.progress-label span { color: #a0a69e; }

.listen-area {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 12px 16px 10px;
  min-height: 0;
}

.audio-controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

.play-button,
.stop-button {
  width: 44px;
  height: 44px;
  border: 0;
  border-radius: 50%;
  display: grid;
  place-items: center;
  cursor: pointer;
  transition: transform 0.15s, background 0.15s, box-shadow 0.15s, opacity 0.15s;
}

.play-button {
  background: var(--green);
  color: #0a3d36;
  box-shadow: 0 0 0 5px var(--green-glow);
}

.stop-button {
  background: #efe8e4;
  color: #8a4b3d;
}

.play-button svg,
.stop-button svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

.play-button:hover {
  background: var(--green-hover);
  transform: translateY(-2px) scale(1.06);
  box-shadow:
    0 0 0 6px var(--green-glow),
    0 8px 18px rgba(67, 239, 210, 0.28);
}

.stop-button:hover:not(:disabled) {
  background: #e7d7d1;
  transform: translateY(-2px) scale(1.06);
  box-shadow: 0 8px 16px rgba(138, 75, 61, 0.16);
}

.play-button:active,
.stop-button:active:not(:disabled) { transform: scale(0.96); }

.play-button:focus-visible,
.stop-button:focus-visible {
  outline: 2px solid var(--green-deep);
  outline-offset: 3px;
}

.play-button:disabled,
.stop-button:disabled {
  opacity: 0.4;
  cursor: default;
  transform: none;
  box-shadow: none;
}

.playback-options {
  display: flex;
  align-items: center;
  gap: 10px;
  width: min(100%, 420px);
}

.speed-control {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
  min-width: 0;
  padding: 8px 12px;
  border-radius: 10px;
  background: var(--surface-muted);
  color: var(--muted);
  font: 600 11px 'DM Sans', sans-serif;
}

.speed-label { flex-shrink: 0; }

.speed-range {
  flex: 1;
  min-width: 0;
  accent-color: var(--green);
  cursor: pointer;
}

.speed-value {
  min-width: 2.6em;
  text-align: right;
  color: var(--green-deep);
  font-variant-numeric: tabular-nums;
}

.autoplay-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
  height: 36px;
  padding: 0 10px;
  border-radius: 10px;
  background: var(--surface-muted);
  cursor: pointer;
  user-select: none;
  color: var(--muted);
  font: 600 11px 'DM Sans', sans-serif;
}

.autoplay-toggle input {
  position: absolute;
  opacity: 0;
  width: 1px;
  height: 1px;
  pointer-events: none;
}

.autoplay-switch {
  position: relative;
  width: 34px;
  height: 20px;
  border-radius: 999px;
  background: #d5dbd3;
  transition: background 0.18s ease;
  flex-shrink: 0;
}

.autoplay-switch::after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(21, 37, 30, 0.22);
  transition: transform 0.18s ease;
}

.autoplay-toggle input:checked + .autoplay-switch {
  background: var(--green);
}

.autoplay-toggle input:checked + .autoplay-switch::after {
  transform: translateX(14px);
}

.autoplay-toggle input:focus-visible + .autoplay-switch {
  outline: 2px solid var(--green);
  outline-offset: 2px;
}

.answer-form {
  padding: 0 16px 14px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  flex: 1;
  min-height: 0;
  margin-top: 0;
}

.answer-slot {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  overflow: hidden;
}

.answer-reveal {
  flex: 0 1 auto;
  min-height: 0;
  max-height: 42%;
  overflow-x: hidden;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: #f4fbf9;
  color: var(--ink);
  font: 500 14px/1.45 'DM Sans', sans-serif;
  scrollbar-width: thin;
  scrollbar-color: #8fd9cb transparent;
}

#answerFormWord .answer-reveal {
  flex: 0 0 auto;
  max-height: none;
  overflow: visible;
}

#answerFormWord.reviewing #answerInputWord {
  display: none;
}

#answerFormWord.reviewing .answer-slot {
  justify-content: flex-start;
}

.answer-reveal[hidden] { display: none !important; }

.answer-reveal.success {
  border-color: color-mix(in srgb, var(--green) 30%, var(--line));
  background: var(--green-soft);
}

.answer-reveal.close {
  border-color: #edd9a3;
  background: #fff8e8;
}

.answer-reveal.error {
  border-color: #efd0c8;
  background: #fdf4f1;
}

.answer-reveal .answer-status {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.2px;
  text-transform: uppercase;
  color: #667268;
}

.answer-reveal.success .answer-status { color: var(--green-deep); }
.answer-reveal.close .answer-status { color: #a67c12; }
.answer-reveal.error .answer-status { color: #9a4333; }

.answer-row {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.answer-row-label {
  font-size: 11px;
  font-weight: 700;
  color: #7a857c;
}

.answer-line {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 8px;
  font-size: 15px;
  line-height: 1.4;
}

.token {
  font-weight: 700;
}

.token.match { color: var(--green-deep); }
.token.close { color: #c48a12; }
.token.mismatch { color: #c24b38; }
.token.neutral { color: #2a5a52; font-weight: 600; }

.answer-detail {
  font-size: 12px;
  font-weight: 500;
  color: #667268;
}

.check-button.is-next {
  background: var(--green-soft);
  color: var(--green-deep);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--green) 40%, var(--line));
}

.check-button.is-next:hover {
  background: color-mix(in srgb, var(--green-soft) 65%, var(--green) 35%);
  transform: translateY(-2px);
  box-shadow:
    inset 0 0 0 1px color-mix(in srgb, var(--green) 40%, var(--line)),
    0 8px 16px rgba(42, 143, 128, 0.16);
}

.form-actions {
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.answer-form input,
.answer-form textarea {
  width: 100%;
  border: 1px solid #e1e5de;
  border-radius: 10px;
  padding: 14px 16px;
  color: var(--ink);
  font: 500 15px/1.45 'DM Sans', sans-serif;
  background: white;
  outline: none;
  transition: 0.15s;
  resize: none;
}

.answer-form input {
  height: 52px;
  min-height: 44px;
  flex: 0 0 auto;
}

.answer-form textarea {
  flex: 1 1 auto;
  min-height: 48px;
  height: auto;
}

.answer-form input:focus,
.answer-form textarea:focus {
  border-color: var(--green);
  box-shadow: 0 0 0 3px var(--green-glow);
}

.answer-form input::placeholder,
.answer-form textarea::placeholder { color: #b0b7af; }

.action-row {
  display: flex;
  gap: 8px;
  align-items: stretch;
  flex-shrink: 0;
}

.skip-button,
.check-button {
  height: 44px;
  border: 0;
  border-radius: 8px;
  font: 700 12px 'DM Sans', sans-serif;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease, filter 0.18s ease;
}

.skip-button {
  flex: 1;
  background: #f8e4df;
  color: #b0432f;
}

.skip-button:hover {
  background: #f0c9c0;
  transform: translateY(-2px);
  box-shadow: 0 8px 16px rgba(176, 67, 47, 0.16);
}

.skip-button:active {
  transform: translateY(0);
  box-shadow: none;
}

.check-button {
  flex: 2;
  background: var(--green);
  color: #0a3d36;
}

.check-button:hover {
  background: var(--green-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 18px rgba(67, 239, 210, 0.28);
}

.check-button:active {
  transform: translateY(0);
  box-shadow: none;
}

.feedback {
  min-height: 18px;
  margin: 0;
  font-size: 12px;
  color: var(--green-mid);
  flex-shrink: 0;
}

.feedback.error { color: #cc6b53; }
.feedback.success { color: var(--green-deep); }
.feedback.close { color: #c48a12; }

.completion {
  margin: 0 16px 16px;
  padding: 14px 16px;
  background: var(--green-soft);
  border-radius: 10px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.completion[hidden] { display: none; }

.completion strong {
  display: block;
  font-size: 13px;
}

.completion p {
  font-size: 12px;
  color: #7b8877;
  margin: 4px 0 0;
}

.completion button {
  margin-left: auto;
  border: 0;
  border-radius: 8px;
  background: var(--surface-muted);
  padding: 10px 14px;
  color: var(--green-deep);
  font: 700 12px 'DM Sans', sans-serif;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.18s ease, transform 0.18s ease, box-shadow 0.18s ease;
}

.completion button:hover {
  background: var(--green-soft);
  transform: translateY(-2px);
  box-shadow: 0 6px 14px rgba(26, 36, 34, 0.1);
}

.completion button:active {
  transform: translateY(0);
  box-shadow: none;
}

footer {
  padding: 8px 0 4px;
  color: #929990;
  font: 700 12px 'Manrope', sans-serif;
  flex-shrink: 0;
}

.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;
}

@media (max-width: 650px) {
  .site-header { padding: 10px 16px 0; }
  .brand-name { font-size: 14px; }
  main { padding: 0 16px 12px; }
  .hero { padding: 14px 0 12px; }
  .hero h1 { font-size: 28px; }
  .hero-description { font-size: 13px; margin-top: 8px; }
  .practice-card { padding: 12px; border-radius: 16px; }
  .topic-picker { max-width: min(200px, 52vw); }
  .topic-menu { min-width: min(280px, 86vw); max-height: min(240px, 40vh); }
  .practice-nav { margin-top: 10px; }
  .nav-tab { padding: 10px 8px; gap: 8px; }
  .nav-tab strong { font-size: 12px; }
  .listen-area { padding: 10px 12px 8px; gap: 10px; }
  .play-button,
  .stop-button { width: 40px; height: 40px; }
  .play-button svg,
  .stop-button svg { width: 16px; height: 16px; }
  .playback-options { width: 100%; gap: 8px; }
  .speed-control { padding: 8px 10px; }
  .autoplay-toggle { padding: 0 8px; }
  .answer-form {
    padding: 0 12px 12px;
    gap: 12px;
  }
  .answer-form input {
    height: 52px;
    font-size: 16px;
    border-radius: 12px;
    padding: 0 16px;
  }
  .answer-form textarea {
    min-height: 48px;
    font-size: 16px;
    border-radius: 12px;
  }
  .answer-reveal { max-height: 36%; }
  #answerFormWord .answer-reveal { max-height: none; }
  .action-row { gap: 10px; }
  .skip-button,
  .check-button {
    height: 48px;
    font-size: 14px;
    border-radius: 10px;
  }
  footer { padding: 10px 0 4px; }
}

[data-theme="dark"] .practice-nav { background: var(--surface-muted); }
[data-theme="dark"] .practice-nav::before { background: var(--white); }
[data-theme="dark"] .exercise { background: #151c1a; }
[data-theme="dark"] .answer-form input,
[data-theme="dark"] .answer-form textarea {
  background: #0b1c1a;
  border-color: var(--line);
  color: var(--ink);
}
[data-theme="dark"] .answer-reveal { background: #14302c; }
[data-theme="dark"] .answer-reveal.success { background: #163a35; }
[data-theme="dark"] .answer-reveal.close { background: #3a3218; border-color: #6a5a28; }
[data-theme="dark"] .answer-reveal.error { background: #3a1f1c; border-color: #6a3832; }
[data-theme="dark"] .skip-button { background: #3a2420; color: #f0b0a4; }
[data-theme="dark"] .skip-button:hover {
  background: #4a2e29;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.28);
}
[data-theme="dark"] .check-button:hover,
[data-theme="dark"] .play-button:hover {
  box-shadow:
    0 0 0 6px var(--green-glow),
    0 8px 18px rgba(0, 0, 0, 0.35);
}
[data-theme="dark"] .stop-button { background: #2a3533; color: #e0b0a4; }
[data-theme="dark"] .stop-button:hover:not(:disabled) {
  background: #35413e;
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.28);
}
[data-theme="dark"] .menu-button:hover,
[data-theme="dark"] .completion button:hover {
  box-shadow: 0 6px 14px rgba(0, 0, 0, 0.28);
}
[data-theme="dark"] .menu-panel {
  box-shadow:
    0 4px 12px rgba(0, 0, 0, 0.25),
    0 18px 40px rgba(0, 0, 0, 0.35);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition: none !important;
  }
  .practice-nav::before {
    transition: left 0.2s ease-out !important;
  }
}