:root {
  --bg: #f3f4f8;
  --bg-gradient: linear-gradient(160deg, #eef0ff 0%, #f7f7fb 45%, #fdf2f8 100%);
  --surface: #ffffff;
  --surface-2: #f8f9fc;
  --border: #e5e7eb;
  --text: #1f2330;
  --text-muted: #6b7280;
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-contrast: #ffffff;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.04), 0 8px 24px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 20px 45px rgba(76, 29, 149, 0.15);
  --radius: 16px;
  --radius-sm: 10px;
}

:root[data-theme="dark"] {
  --bg: #12131c;
  --bg-gradient: linear-gradient(160deg, #171826 0%, #12131c 50%, #1a1424 100%);
  --surface: #1b1d29;
  --surface-2: #22243a;
  --border: #2e3142;
  --text: #eef0f7;
  --text-muted: #9599ad;
  --primary: #818cf8;
  --primary-dark: #6366f1;
  --primary-contrast: #0f1020;
  --success: #4ade80;
  --success-bg: #113321;
  --danger: #f87171;
  --danger-bg: #3a1418;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 20px 45px rgba(0, 0, 0, 0.45);
}

* { box-sizing: border-box; }

html {
  background: var(--bg);
}

body {
  margin: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-gradient);
  color: var(--text);
  min-height: 100vh;
  min-height: 100dvh;
  padding-bottom: env(safe-area-inset-bottom);
  -webkit-font-smoothing: antialiased;
}

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

h1, h2, h3 { margin: 0; letter-spacing: -0.02em; }

.muted { color: var(--text-muted); }
.error { color: var(--danger); }

/* ---------- Buttons ---------- */
button { font-family: inherit; }

.btn-primary, .btn-secondary, .btn-ghost {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 18px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 14px;
  border: none;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--primary-contrast);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.35);
}
.btn-primary:hover { transform: translateY(-1px); }
.btn-primary:disabled { opacity: 0.6; cursor: not-allowed; transform: none; }
.btn-primary.disabled { opacity: 0.4; pointer-events: none; }

.btn-secondary {
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-secondary:hover { background: var(--border); }

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}
.btn-ghost:hover { color: var(--text); border-color: var(--text-muted); }

.btn-danger {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 18px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 14px;
  border: none;
  cursor: pointer;
  background: linear-gradient(135deg, #f87171, var(--danger));
  color: #fff;
  box-shadow: 0 6px 16px rgba(220, 38, 38, 0.35);
  transition: transform 0.15s ease;
}
.btn-danger:hover { transform: translateY(-1px); }

.btn-block { width: 100%; margin-top: 8px; }

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  background: transparent;
  border: none;
  cursor: pointer;
  font-size: 16px;
  border-radius: 999px;
  line-height: 1;
  color: var(--text-muted);
  transition: background 0.15s ease, color 0.15s ease, transform 0.1s ease;
}
.icon-btn:hover { background: var(--surface-2); color: var(--text); transform: translateY(-1px); }
.icon-btn:active { transform: scale(0.92); }

.icon-btn-danger:hover { background: var(--danger-bg); color: var(--danger); }

/* ---------- Auth page ---------- */
.auth-page {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 24px;
  padding-top: calc(24px + env(safe-area-inset-top));
  padding-bottom: calc(24px + env(safe-area-inset-bottom));
}

.auth-theme-toggle {
  position: fixed;
  top: calc(20px + env(safe-area-inset-top));
  right: 20px;
}

.auth-card {
  width: 100%;
  max-width: 400px;
  background: var(--surface);
  border-radius: 24px;
  padding: 40px 32px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
}

.brand { text-align: center; margin-bottom: 24px; }
.brand-mark { font-size: 40px; margin-bottom: 8px; }
.brand h1 { font-size: 24px; font-weight: 800; }
.brand p { color: var(--text-muted); margin: 6px 0 0; font-size: 14px; }

.tabs {
  display: flex;
  background: var(--surface-2);
  border-radius: 999px;
  padding: 4px;
  margin-bottom: 24px;
}
.tab-btn {
  flex: 1;
  padding: 9px 12px;
  border: none;
  background: transparent;
  border-radius: 999px;
  font-weight: 600;
  font-size: 13px;
  cursor: pointer;
  color: var(--text-muted);
  transition: all 0.15s ease;
}
.tab-btn.active {
  background: var(--surface);
  color: var(--primary);
  box-shadow: var(--shadow);
}

.tab-panel { display: none; flex-direction: column; gap: 8px; }
.tab-panel.active { display: flex; }

label { font-size: 13px; font-weight: 600; color: var(--text-muted); margin-top: 4px; }

input[type="text"], input[type="email"], input[type="color"], select, textarea {
  width: 100%;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text);
  font-size: 15px;
  font-family: inherit;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
input[type="text"]:focus, input[type="email"]:focus, textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}
textarea { resize: vertical; min-height: 90px; }
input[type="color"] { padding: 4px; height: 42px; cursor: pointer; }
select { cursor: pointer; }

.form-hint { font-size: 12px; color: var(--text-muted); margin: 4px 0 0; }
.form-msg { font-size: 13px; font-weight: 600; min-height: 18px; margin: 4px 0 0; color: var(--success); }
.form-msg.error { color: var(--danger); }

/* ---------- App shell ---------- */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 32px;
  padding-top: calc(16px + env(safe-area-inset-top));
  background: var(--surface);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar-brand { font-weight: 800; font-size: 18px; color: var(--text); }
.topbar-actions { display: flex; align-items: center; gap: 8px; }

.page {
  max-width: 960px;
  margin: 0 auto;
  padding: 32px 24px 80px;
}

.page-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}
.page-header h1 { font-size: 26px; font-weight: 800; }
.page-header-actions { display: flex; gap: 10px; }

.info-hint {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  font-size: 13px;
  line-height: 1.5;
  color: var(--text-muted);
  margin: -12px 0 24px;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 16px;
  font-weight: 700;
  color: var(--primary);
  padding: 10px 4px;
  margin: -10px 0 4px -4px;
}
.back-link:hover { color: var(--primary-dark); }

/* ---------- Topics grid ---------- */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px;
}

.topic-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 6px solid var(--accent, var(--primary));
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.topic-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--accent, var(--primary));
  opacity: 0.14;
  pointer-events: none;
}
.topic-card > * { position: relative; z-index: 1; }

.topic-card:hover { transform: translateY(-3px); }

.topic-card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 6px;
}
.topic-card h3 {
  font-size: 17px;
  font-weight: 800;
  color: var(--accent, var(--primary));
}

.topic-card-top-actions {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-shrink: 0;
}

.topic-card-actions {
  display: flex;
  gap: 8px;
  margin-top: 16px;
}
.topic-card-actions a { flex: 1; text-align: center; padding: 8px 12px; }

.badge {
  font-size: 11px;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 999px;
  white-space: nowrap;
}
.badge-due { background: var(--danger-bg); color: var(--danger); }
.badge-ok { background: var(--success-bg); color: var(--success); }

/* ---------- Words list ---------- */
.words-list { display: flex; flex-direction: column; gap: 10px; }

.word-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
}
.word-main { display: flex; flex-direction: column; gap: 2px; min-width: 0; flex: 1 1 auto; }
.word-main strong { font-size: 15px; }
.word-meta { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }

.chip {
  font-size: 12px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--text-muted);
  border: 1px solid var(--border);
  white-space: nowrap;
  flex-shrink: 0;
}
.chip-due { background: var(--danger-bg); color: var(--danger); border-color: transparent; }

/* ---------- Dialogs ---------- */
.dialog {
  border: none;
  border-radius: var(--radius);
  padding: 28px;
  width: 100%;
  max-width: 420px;
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow-lg);
}
.dialog::backdrop { background: rgba(15, 15, 25, 0.5); backdrop-filter: blur(2px); }
.dialog form { display: flex; flex-direction: column; gap: 8px; }
.dialog h2 { font-size: 18px; margin-bottom: 8px; }
.confirm-message { margin: 0; font-size: 15px; line-height: 1.5; }

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
  margin-top: 16px;
}

/* ---------- Quiz ---------- */
.quiz-wrap { max-width: 520px; margin: 0 auto; }

.quiz-progress {
  height: 8px;
  border-radius: 999px;
  background: var(--surface-2);
  overflow: hidden;
  margin: 16px 0 32px;
}
.quiz-progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--primary), var(--primary-dark));
  transition: width 0.3s ease;
}

.quiz-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 40px 32px;
  box-shadow: var(--shadow-lg);
  text-align: center;
  animation: card-in 0.25s ease;
}

@keyframes card-in {
  from { opacity: 0; transform: translateY(8px) scale(0.98); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

.quiz-counter { color: var(--text-muted); font-size: 13px; font-weight: 700; margin-bottom: 12px; }

.quiz-term-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  margin-bottom: 24px;
}
.quiz-term { font-size: 30px; font-weight: 800; }

#answer-form { display: flex; flex-direction: column; gap: 12px; }

.answer-input-row { display: flex; gap: 8px; }
.answer-input-row input {
  flex: 1;
  text-align: center;
  font-size: 17px;
  padding: 14px;
}

.mic-btn {
  border: 1px solid var(--border);
  background: var(--surface-2);
  font-size: 20px;
  width: 48px;
  flex-shrink: 0;
}
.mic-btn.listening {
  background: var(--danger-bg);
  color: var(--danger);
  animation: mic-pulse 1s ease-in-out infinite;
}

@keyframes mic-pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(239, 68, 68, 0.4); }
  50% { box-shadow: 0 0 0 8px transparent; }
}

#answer-form button[type="submit"] { padding: 12px; }

#quiz-feedback { margin-top: 20px; }
.feedback { font-weight: 700; font-size: 15px; margin-bottom: 12px; }
.feedback-correct { color: var(--success); }
.feedback-wrong { color: var(--danger); }
.feedback-actions { display: flex; gap: 10px; }
.feedback-actions button { flex: 1; }
.feedback-note {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  font-size: 15px;
  line-height: 1.5;
  text-align: left;
  margin-bottom: 16px;
  white-space: pre-wrap;
}

.quiz-summary {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 48px 32px;
  text-align: center;
  box-shadow: var(--shadow-lg);
}
.quiz-summary h2 { font-size: 24px; margin-bottom: 12px; }
.quiz-summary p { color: var(--text-muted); margin-bottom: 24px; }

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--text);
  color: var(--bg);
  padding: 12px 20px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  opacity: 0;
  transition: opacity 0.3s ease, transform 0.3s ease;
  z-index: 100;
  box-shadow: var(--shadow-lg);
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast-error { background: var(--danger); color: #fff; }

/* ---------- Settings ---------- */
.settings-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  max-width: 560px;
}

.settings-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}
.settings-row h3 { font-size: 16px; margin-bottom: 6px; }
.settings-row p { margin: 0; font-size: 14px; line-height: 1.5; }

.settings-row-test {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}

.switch {
  position: relative;
  display: inline-block;
  width: 48px;
  height: 28px;
  flex-shrink: 0;
}
.switch input {
  position: absolute;
  inset: 0;
  opacity: 0;
  margin: 0;
  padding: 0;
  border: none;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
}
.switch-track {
  position: absolute;
  inset: 0;
  display: block;
  background: var(--border);
  border-radius: 999px;
  transition: background 0.2s ease;
  pointer-events: none;
}
.switch-thumb {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 22px;
  height: 22px;
  background: #fff;
  border-radius: 50%;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  transition: transform 0.2s ease;
}
.switch input:checked ~ .switch-track {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
}
.switch input:checked ~ .switch-track .switch-thumb {
  transform: translateX(20px);
}
.switch input:focus-visible ~ .switch-track {
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.35);
}

@media (max-width: 600px) {
  .topbar {
    padding: 14px 16px;
    padding-top: calc(20px + env(safe-area-inset-top));
    gap: 8px;
  }
  .topbar-actions { gap: 4px; }
  .page { padding: 28px 16px 64px; }
  .auth-card { padding: 32px 22px; }
  .settings-row { flex-wrap: wrap; }
  .icon-btn { width: 44px; height: 44px; }
  .page-header-actions .icon-btn,
  .topic-card-top-actions .icon-btn,
  .word-meta .icon-btn {
    width: 40px;
    height: 40px;
  }
}