:root {
  color-scheme: light;
  --bg: #f5f5f7;
  --surface: rgba(255, 255, 255, 0.92);
  --surface-strong: #ffffff;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --line: #d2d2d7;
  --primary: #1d1d1f;
  --primary-dark: #000000;
  --accent: #515154;
  --danger: #d70015;
  --warning: #8a5a00;
  --soft: #e8e8ed;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.08);
  --jp-size: clamp(20px, 5.2vw, 28px);
  --reading-size: clamp(14px, 3.8vw, 18px);
  --meaning-size: clamp(15px, 4vw, 18px);
  --today-meaning-size: clamp(20px, 5.4vw, 26px);
  --kana-size: clamp(64px, 20vw, 150px);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
}

button,
input,
textarea,
select {
  font: inherit;
}

button,
.file-button {
  min-height: 46px;
  border: 0;
  border-radius: 14px;
  background: var(--primary);
  color: #fff;
  padding: 0 16px;
  font-weight: 700;
  cursor: pointer;
}

button:hover,
.file-button:hover {
  background: var(--primary-dark);
}

button:disabled {
  background: #c7c7cc;
  color: #ffffff;
  opacity: 0.75;
  cursor: not-allowed;
}

input,
textarea,
select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.88);
  color: var(--text);
  padding: 12px 14px;
  outline: none;
}

input:focus,
textarea:focus,
select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px rgba(29, 29, 31, 0.1);
}

label {
  display: grid;
  gap: 8px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 20px;
  background: rgba(255, 255, 255, 0.78);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(18px);
  position: sticky;
  top: 0;
  z-index: 10;
}

.app-header h1,
.section-heading h2 {
  margin: 0;
  letter-spacing: 0;
}

.app-header h1 {
  font-size: clamp(20px, 5.4vw, 24px);
}

.section-heading h2 {
  font-size: clamp(18px, 4.8vw, 22px);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
}

.source-date {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.app-shell {
  display: grid;
  gap: 16px;
  width: min(1120px, 100%);
  margin: 0 auto;
  padding: 16px;
}

.today-card,
.panel,
.study-card,
.kana-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.today-card {
  display: grid;
  gap: 18px;
  padding: 22px;
}

.panel {
  display: none;
  gap: 18px;
  padding: 18px;
}

.panel.active {
  display: grid;
}

.section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.heading-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 8px;
}

.count-badge {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  border-radius: 999px;
  background: var(--soft);
  color: var(--text);
  padding: 0 12px;
  font-size: 13px;
  font-weight: 800;
  white-space: nowrap;
}

.sentence-display {
  display: grid;
  gap: 10px;
}

.sentence-display p {
  margin: 0;
}

.jp {
  font-size: var(--jp-size);
  font-weight: 800;
  line-height: 1.45;
}

.reading {
  color: var(--accent);
  font-size: var(--reading-size);
  font-weight: 700;
  line-height: 1.5;
}

.meaning {
  color: var(--muted);
  font-size: var(--meaning-size);
  line-height: 1.5;
}

.today-card .meaning {
  color: var(--text);
  font-size: var(--today-meaning-size);
  font-weight: 800;
}

.today-card .jp {
  margin-top: 4px;
}

.tabs {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  overflow-x: auto;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(232, 232, 237, 0.8);
}

.tab {
  min-width: 74px;
  min-height: 42px;
  background: transparent;
  color: var(--text);
}

.tab:hover {
  background: rgba(255, 255, 255, 0.52);
}

.tab.active {
  background: var(--surface-strong);
  color: var(--text);
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.08);
}

.word-form,
.quick-add,
.tools,
.style-options,
.word-study-filter,
.manage-actions,
.api-key-box {
  display: grid;
  gap: 12px;
}

.word-form {
  grid-template-columns: 1fr;
}

.button-row,
.button-grid,
.mark-row {
  display: grid;
  gap: 10px;
}

.button-row,
.mark-row {
  grid-template-columns: repeat(2, 1fr);
}

.today-card .button-row {
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
}

.button-grid {
  grid-template-columns: repeat(2, 1fr);
}

.ghost-button {
  border: 1px solid var(--line);
  background: var(--surface-strong);
  color: var(--text);
}

.ghost-button:hover {
  background: var(--soft);
}

.ghost-button.active {
  border-color: transparent;
  background: #fff6d9;
  color: var(--warning);
}

.danger-button {
  background: var(--danger);
}

.danger-button:hover {
  background: #b80012;
}

.icon-button {
  width: 46px;
  padding: 0;
  border-radius: 50%;
  font-size: 22px;
}

.word-list,
.sentence-list {
  display: grid;
  gap: 10px;
}

.word-item,
.sentence-item {
  display: grid;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--surface-strong);
  padding: 14px;
}

.sentence-title-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}

.sentence-number,
.ai-badge {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  border-radius: 999px;
  padding: 0 9px;
  font-size: 12px;
  font-weight: 800;
}

.sentence-number {
  background: var(--soft);
  color: var(--text);
}

.ai-badge {
  background: #1d1d1f;
  color: #fff;
}

.word-main,
.sentence-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.word-main strong {
  font-size: 18px;
}

.word-meta,
.sentence-meta,
.helper-text {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.5;
}

.helper-text {
  margin: 0;
}

#geminiKeyStatus {
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface-strong);
  padding: 10px 12px;
  color: var(--text);
  font-weight: 700;
}

.small-button {
  min-height: 36px;
  border-radius: 12px;
  padding: 0 10px;
  font-size: 13px;
}

.study-card {
  display: grid;
  gap: 16px;
  padding: 18px;
}

.kana-card {
  display: grid;
  place-items: center;
  min-height: 210px;
  padding: 22px;
  text-align: center;
}

.kana-character {
  margin: 0;
  font-size: var(--kana-size);
  font-weight: 800;
  line-height: 1;
  letter-spacing: 0;
}

.word-study-card .kana-character {
  max-width: 100%;
  font-size: clamp(40px, 13vw, 88px);
  line-height: 1.12;
  overflow-wrap: anywhere;
}

.kana-romaji {
  margin: 6px 0 0;
  color: var(--text);
  font-size: clamp(22px, 6vw, 28px);
  font-weight: 800;
}

.kana-korean {
  margin: 0;
  color: var(--muted);
  font-size: 18px;
  font-weight: 700;
}

.segmented-control {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 6px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--soft);
  padding: 5px;
}

.segmented-control button {
  min-height: 40px;
  background: transparent;
  color: var(--text);
}

.segmented-control button:hover {
  background: rgba(255, 255, 255, 0.52);
}

.segmented-control button.active {
  background: var(--surface-strong);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.08);
}

.kana-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(72px, 1fr));
  gap: 10px;
}

.kana-tile {
  display: grid;
  gap: 4px;
  min-height: 82px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--surface-strong);
  color: var(--text);
  cursor: pointer;
}

.kana-tile.active {
  border-color: var(--text);
  box-shadow: inset 0 0 0 1px var(--text);
}

.kana-tile strong {
  font-size: 30px;
  line-height: 1;
}

.kana-tile span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
}

.range-label {
  grid-template-columns: 1fr;
}

.range-label span {
  color: var(--text);
}

.switch {
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
}

.switch input {
  width: auto;
}

.file-button {
  display: inline-grid;
  place-items: center;
  text-align: center;
}

.file-button input {
  display: none;
}

.toast {
  position: fixed;
  left: 16px;
  right: 16px;
  bottom: 18px;
  display: none;
  max-width: 520px;
  margin: 0 auto;
  border-radius: 16px;
  background: #1d1d1f;
  color: #fff;
  padding: 14px 16px;
  text-align: center;
  box-shadow: var(--shadow);
}

.toast.show {
  display: block;
}

.hidden {
  display: none;
}

@media (min-width: 760px) {
  .app-header {
    padding: 24px 32px;
  }

  .app-shell {
    padding: 24px;
  }

  .word-form {
    grid-template-columns: repeat(2, 1fr);
  }

  .word-form button {
    grid-column: span 2;
  }

  .tools,
  .style-options,
  .manage-actions {
    grid-template-columns: 1fr auto auto auto;
    align-items: end;
  }

  .style-options {
    grid-template-columns: repeat(3, 1fr);
  }

  .button-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .range-label {
    grid-template-columns: auto 1fr auto;
    align-items: center;
  }
}

@media (max-width: 480px) {
  .app-header {
    padding: 16px;
  }

  .app-shell {
    gap: 12px;
    padding: 12px;
  }

  .today-card,
  .panel {
    border-radius: 20px;
    padding: 16px;
  }

  .study-card,
  .kana-card {
    border-radius: 20px;
    padding: 16px;
  }

  button,
  .file-button {
    min-height: 42px;
    border-radius: 12px;
    padding: 0 12px;
    font-size: 14px;
  }

  .tab {
    min-width: 68px;
    min-height: 38px;
    font-size: 13px;
  }

  .section-heading {
    align-items: flex-start;
  }

  .heading-actions {
    justify-content: flex-start;
  }
}