* { box-sizing: border-box; }

body {
    font-family: Arial, sans-serif;
    text-align: center;
    background-color: #f0f0f0;
    margin: 0;
    padding: 16px 20px 40px;
}

h1 { color: #333; margin: 8px 0 16px; }

/* ===== TOP BAR (nav + auth) ===== */
.top-bar {
    display: flex; align-items: center; justify-content: space-between;
    margin-bottom: 4px;
}
.nav-back { text-align: left; }
.nav-back a { color: #666; text-decoration: none; font-size: 14px; }
.nav-back a:hover { color: #333; }

/* ===== AUTH BAR ===== */
.auth-bar {
    display: flex; align-items: center; gap: 8px; font-size: 13px;
}
.auth-avatar {
    width: 28px; height: 28px; border-radius: 50%; object-fit: cover;
}
.auth-name { color: #555; max-width: 140px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.auth-btn {
    padding: 5px 12px; font-size: 12px; border-radius: 20px; margin: 0;
}
.auth-btn-in  { background: #4285F4; }
.auth-btn-in:hover  { background: #3367D6; }
.auth-btn-out { background: #888; }
.auth-btn-out:hover { background: #666; }

/* ===== BATCH BANNER ===== */
.batch-banner {
    max-width: 620px; margin: 0 auto 12px;
    background: #43a047; color: white;
    border-radius: 10px; padding: 10px 18px;
    font-size: 15px; font-weight: bold;
    animation: slideIn 0.3s ease;
}
@keyframes slideIn {
    from { opacity: 0; transform: translateY(-8px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ===== PROGRESS ===== */
#progress-container { max-width: 620px; margin: 0 auto 18px; }
#progress-text { font-size: 14px; color: #555; margin-bottom: 5px; }
#progress-bar { background:#ddd; border-radius:8px; height:11px; overflow:hidden; }
#progress-bar-fill {
    height:100%; width:0%;
    background: linear-gradient(90deg,#4CAF50,#81c784);
    border-radius:8px; transition: width 0.4s;
}

/* ===== TABS ===== */
.tabs { margin-bottom: 18px; display:flex; flex-wrap:wrap; justify-content:center; gap:6px; }
.tab-btn {
    padding: 9px 16px;
    background-color: #bbb; color: white;
    border: none; cursor: pointer; border-radius: 6px;
    font-size: 14px; transition: background 0.2s;
}
.tab-btn:hover  { background-color: #999; }
.tab-btn.active { background-color: #4CAF50; }

/* ===== CONTENT ===== */
.content {
    max-width: 620px; margin: 0 auto;
    background: white; padding: 22px 18px;
    border-radius: 12px; box-shadow: 0 2px 12px rgba(0,0,0,0.11);
}
.section-hint { color:#888; font-size:14px; margin-top:0; }

/* ===== CARD ===== */
#card, #review-card, #tone-card, #speak-card, #rv-card {
    min-height: 170px; display:flex; flex-direction:column;
    justify-content:center; align-items:center;
    border: 2px solid #ddd; border-radius:12px;
    margin-bottom:16px; padding:18px; position:relative;
}
#card-front, #card-back, #rv-front, #rv-back {
    display:flex; flex-direction:column; align-items:center; width:100%;
}
#chinese, #rad-char, #tone-chinese, #speak-chinese, #review-chinese {
    font-size: 60px; line-height:1.2; margin-bottom:6px;
}
#tone-card #tone-chinese { font-size: 52px; }
#speak-card #speak-chinese { font-size: 56px; }
#pinyin, #rad-pinyin, #speak-pinyin, #review-pinyin { font-size:20px; color:#666; }
#russian, #rad-russian, #review-russian { font-size:22px; color:#333; }

.strokes-badge {
    font-size:12px; color:#888; background:#f0f0f0;
    border-radius:10px; padding:2px 8px; margin-top:4px;
}

.empty-msg { color:#999; font-size:16px; line-height:1.7; padding:10px 0; }

/* ===== TTS / PLAY / MIC buttons ===== */
button {
    padding: 9px 20px; background:#2196F3; color:white;
    border:none; border-radius:6px; cursor:pointer; margin:4px;
    font-size:14px; transition:background 0.18s;
}
button:hover { background:#1976D2; }

.tts-button {
    background:none; border:1px solid #ccc; border-radius:50%;
    width:34px; height:34px; font-size:15px; cursor:pointer;
    margin-top:8px; padding:0; transition:background 0.18s;
}
.tts-button:hover { background:#f0f0f0; }

.play-button {
    background:#ff7043; color:white; font-size:15px;
    padding:10px 24px; margin-bottom:14px;
}
.play-button:hover { background:#e64a19; }

.mic-button {
    background:#7b1fa2; color:white; font-size:22px;
    width:60px; height:60px; border-radius:50%; padding:0;
    margin:0 8px; transition: transform 0.15s, background 0.18s;
}
.mic-button:hover    { background:#6a1b9a; }
.mic-button.recording { background:#c62828; transform:scale(1.12); animation: pulse 1s infinite; }

@keyframes pulse {
    0%,100% { box-shadow:0 0 0 0 rgba(198,40,40,0.4); }
    50%      { box-shadow:0 0 0 10px rgba(198,40,40,0); }
}

/* ===== SRS BUTTONS ===== */
#srs-buttons, #review-srs-buttons, #rv-srs {
    display:flex; justify-content:center; gap:14px; margin-top:10px;
}
.btn-unknown { background:#e53935; min-width:120px; }
.btn-unknown:hover { background:#c62828; }
.btn-known   { background:#43a047; min-width:120px; }
.btn-known:hover   { background:#2e7d32; }

/* ===== QUIZ ===== */
.quiz-prompt { font-size:13px; color:#888; margin-bottom:4px; }
.quiz-question {
    font-size:26px; font-weight:bold; margin:8px 0 16px; color:#222;
}
.quiz-options {
    display:grid; grid-template-columns:1fr 1fr; gap:10px; margin-bottom:14px;
}
.option-button {
    display:flex; flex-direction:column; align-items:center;
    padding:12px 8px; background:#f5f5f5; color:#222;
    border:2px solid #ddd; border-radius:10px;
    cursor:pointer; font-size:14px; transition:background 0.15s,border-color 0.15s;
    margin:0;
}
.option-button:hover:not(:disabled) { background:#e3f2fd; border-color:#90caf9; }
.option-button:disabled { cursor:default; }
.option-button.correct  { background:#e8f5e9; border-color:#43a047; }
.option-button.incorrect{ background:#ffebee; border-color:#e53935; }

.opt-chinese { font-size:30px; margin-bottom:3px; line-height:1.2; }
.opt-pinyin  { font-size:12px; color:#666; }
.opt-russian { font-size:12px; color:#444; margin-top:2px; }

/* Radicals quiz: 2×2 grid with big characters */
.rad-grid { grid-template-columns:1fr 1fr; }
.rad-option { font-size:48px; padding:16px; min-height:80px; }

.quiz-feedback {
    min-height:24px; font-size:14px; margin-bottom:10px;
    display:flex; align-items:center; justify-content:center;
    flex-wrap:wrap; gap:4px;
}
.fb-ok  { color:#2e7d32; font-weight:bold; }
.fb-err { color:#c62828; font-weight:bold; }

/* ===== TONE EXERCISE ===== */
#tone-pinyin-stripped {
    font-size:20px; color:#999; letter-spacing:2px;
}
#tone-syllables {
    display:flex; flex-wrap:wrap; justify-content:center; gap:16px;
    margin:16px 0;
}
.tone-block { display:flex; flex-direction:column; align-items:center; }
.tone-label { font-size:18px; color:#555; margin-bottom:6px; }
.tone-btns  { display:flex; gap:5px; }
.tone-btn {
    width:36px; height:36px; border-radius:8px;
    background:#f0f0f0; color:#333; border:2px solid #ddd;
    font-size:15px; font-weight:bold; cursor:pointer; padding:0;
    transition:background 0.15s, border-color 0.15s;
}
.tone-btn:hover:not(:disabled)  { background:#e3f2fd; border-color:#90caf9; }
.tone-btn.selected   { background:#bbdefb; border-color:#2196F3; color:#1565c0; }
.tone-btn.tone-correct { background:#c8e6c9; border-color:#43a047; color:#1b5e20; }
.tone-btn.tone-wrong   { background:#ffcdd2; border-color:#e53935; color:#b71c1c; }
.tone-btn:disabled { opacity:0.7; cursor:default; }

/* ===== SPEAKING EXERCISE ===== */
#speak-controls { display:flex; align-items:center; justify-content:center; gap:12px; margin:14px 0; }
#speak-result   { font-size:16px; color:#333; margin:6px 0; min-height:22px; }

/* ===== HUB PAGE (index.html inline styles supplement) ===== */
@media(max-width:500px) {
    .opt-chinese { font-size:24px; }
    .rad-option  { font-size:36px; }
    #chinese, #rad-char { font-size:48px; }
}