/* Word Problems - 数学应用题 */
* { margin: 0; padding: 0; box-sizing: border-box; }

.wp-fullscreen { width: 100vw; min-height: 100vh; display: flex; flex-direction: column; background: linear-gradient(180deg, #EEF2FF, #E0E7FF); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif; overflow-x: hidden; }
.wp-header { display: flex; align-items: center; padding: 12px 16px; background: linear-gradient(135deg, #6366F1, #8B5CF6); color: #fff; position: sticky; top: 0; z-index: 100; min-height: 52px; }
.back-btn-wrap { position: relative; flex-shrink: 0; }
.back-btn { display: flex; align-items: center; gap: 4px; color: #fff; text-decoration: none; font-size: 14px; padding: 4px 0; }
.back-overlay { display: none; position: absolute; top: -8px; left: -8px; right: -8px; bottom: -8px; cursor: pointer; z-index: 1; }
.back-overlay.active { display: block; }
.wp-header .title { flex: 1; text-align: center; font-size: 17px; font-weight: 600; }
.header-actions { flex-shrink: 0; display: flex; align-items: center; gap: 8px; }
.points-badge { display: flex; align-items: center; gap: 4px; background: rgba(255,255,255,0.2); padding: 4px 10px; border-radius: 14px; font-size: 13px; color: #FFD700; font-weight: 600; cursor: pointer; }
.points-badge i { font-size: 12px; }
.points-badge.pulse { animation: badgePulse 0.5s ease; }
.points-badge.pulse-big { animation: badgePulseBig 0.6s ease; }
@keyframes badgePulse { 0% { transform: scale(1); } 40% { transform: scale(1.25); background: rgba(255,215,0,0.5); } 100% { transform: scale(1); } }
@keyframes badgePulseBig { 0% { transform: scale(1); } 30% { transform: scale(1.4); background: rgba(255,100,0,0.6); } 100% { transform: scale(1); } }

.wp-main { flex: 1; display: flex; flex-direction: column; }
.screen { flex: 1; display: flex; flex-direction: column; padding: 16px; animation: fadeIn 0.3s ease; }
.screen.hidden { display: none; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }

/* Menu */
.menu-title { text-align: center; font-size: 28px; font-weight: 800; color: #4338CA; margin-bottom: 4px; }
.menu-desc { text-align: center; font-size: 14px; color: #7C3AED; margin-bottom: 20px; }
.opt-group { max-width: 400px; margin: 0 auto 16px; width: 100%; }
.opt-label { font-size: 13px; color: #6B7280; text-align: center; margin-bottom: 8px; }

.type-btns { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; }

.type-btn {
    padding: 10px 16px;
    background: #fff;
    border: 2px solid #E0E7FF;
    border-radius: 12px;
    font-size: 14px;
    font-weight: 600;
    color: #4338CA;
    cursor: pointer;
    transition: all 0.2s;
    -webkit-tap-highlight-color: transparent;
}
.type-btn:active { transform: scale(0.96); }
.type-btn.active { border-color: #6366F1; background: #EEF2FF; box-shadow: 0 2px 8px rgba(99,102,241,0.2); }

.start-btn { display: flex; align-items: center; justify-content: center; gap: 8px; margin: 16px auto 20px; padding: 14px 48px; background: linear-gradient(135deg, #6366F1, #8B5CF6); border: none; border-radius: 16px; color: #fff; font-size: 18px; font-weight: 700; cursor: pointer; box-shadow: 0 4px 16px rgba(99,102,241,0.3); }
.start-btn:active { transform: scale(0.96); }
.menu-stats { display: flex; justify-content: center; gap: 24px; margin-bottom: 20px; }
.stat-item { text-align: center; }
.stat-value { font-size: 24px; font-weight: 800; color: #6366F1; }
.stat-label { font-size: 12px; color: #9CA3AF; margin-top: 2px; }
.lottery-entry-btn { display: flex; align-items: center; justify-content: center; gap: 8px; margin: 0 auto; padding: 12px 28px; background: linear-gradient(135deg, #F59E0B, #D97706); border: none; border-radius: 24px; color: #fff; font-size: 16px; font-weight: 700; cursor: pointer; box-shadow: 0 4px 16px rgba(245,158,11,0.3); }
.lottery-entry-btn:active { transform: scale(0.96); }

/* Game */
.game-top { display: flex; align-items: center; justify-content: space-between; margin-bottom: 6px; }
.game-progress-info { font-size: 14px; font-weight: 600; color: #4338CA; }
.game-score { font-size: 14px; font-weight: 600; color: #10B981; }
.streak-badge { display: inline-block; }
.streak-badge span { display: inline-block; background: linear-gradient(135deg, #FF6B35, #F7931E); color: #fff; padding: 3px 10px; border-radius: 12px; font-size: 12px; font-weight: 700; animation: streakPop 0.4s ease; }
.streak-badge.hidden { display: none; }
.streak-badge.fire span { background: linear-gradient(135deg, #FF4136, #FF6B35); }
@keyframes streakPop { 0% { transform: scale(0.5); opacity: 0; } 60% { transform: scale(1.15); } 100% { transform: scale(1); opacity: 1; } }
.game-progress-bar { height: 4px; background: #E0E7FF; border-radius: 2px; margin-bottom: 12px; overflow: hidden; }
.progress-fill { height: 100%; background: linear-gradient(90deg, #6366F1, #8B5CF6); border-radius: 2px; transition: width 0.3s ease; width: 0; }

/* Problem Card */
.problem-card {
    background: #fff;
    border-radius: 16px;
    padding: 18px 16px;
    margin-bottom: 14px;
    box-shadow: 0 2px 12px rgba(99,102,241,0.06);
    position: relative;
}

.problem-type-tag {
    display: inline-block;
    padding: 2px 10px;
    background: #EEF2FF;
    border-radius: 8px;
    font-size: 12px;
    font-weight: 600;
    color: #6366F1;
    margin-bottom: 10px;
}

.problem-text {
    font-size: 16px;
    line-height: 1.7;
    color: #1E1B4B;
}

/* Choices */
.choices {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 14px;
}

.choice-btn {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 14px 16px;
    background: #fff;
    border: 2px solid #E0E7FF;
    border-radius: 14px;
    font-size: 15px;
    font-weight: 600;
    color: #1E1B4B;
    cursor: pointer;
    transition: all 0.15s;
    -webkit-tap-highlight-color: transparent;
}

.choice-btn:active { transform: scale(0.98); }

.choice-label {
    width: 28px; height: 28px;
    background: #EEF2FF;
    border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    font-size: 13px; font-weight: 700; color: #6366F1;
    flex-shrink: 0;
}

.choice-btn.correct { border-color: #6EE7B7; background: #ECFDF5; }
.choice-btn.correct .choice-label { background: #6EE7B7; color: #065F46; }
.choice-btn.wrong { border-color: #FCA5A5; background: #FEF2F2; }
.choice-btn.wrong .choice-label { background: #FCA5A5; color: #991B1B; }
.choice-btn.disabled { pointer-events: none; opacity: 0.6; }

/* Explain Card */
.explain-card {
    background: #FFF7ED;
    border: 2px solid #FED7AA;
    border-radius: 14px;
    padding: 14px 16px;
    animation: fadeIn 0.3s ease;
}
.explain-card.hidden { display: none; }
.explain-title { font-size: 14px; font-weight: 700; color: #D97706; margin-bottom: 6px; }
.explain-text { font-size: 14px; color: #78350F; line-height: 1.6; margin-bottom: 12px; }
.next-btn {
    display: flex; align-items: center; justify-content: center; gap: 6px;
    width: 100%; padding: 12px; background: linear-gradient(135deg, #6366F1, #8B5CF6);
    border: none; border-radius: 12px; color: #fff; font-size: 16px; font-weight: 600; cursor: pointer;
}
.next-btn:active { transform: scale(0.97); }

/* Points Popup */
.points-popup { position: fixed; top: 50%; left: 50%; transform: translate(-50%,-50%); font-size: 28px; font-weight: 800; color: #F59E0B; text-shadow: 0 2px 8px rgba(0,0,0,0.15); pointer-events: none; z-index: 200; }
.points-popup.hidden { display: none; }
.points-popup.show { display: block; animation: pointsFly 0.8s ease-out forwards; }
@keyframes pointsFly { 0% { opacity:1; transform: translate(-50%,-50%) scale(0.5); } 30% { opacity:1; transform: translate(-50%,-70%) scale(1.2); } 100% { opacity:0; transform: translate(-50%,-120%) scale(1); } }

/* Complete */
.complete-card { background: #fff; border-radius: 20px; padding: 32px 24px; text-align: center; box-shadow: 0 4px 20px rgba(99,102,241,0.1); max-width: 360px; margin: auto; width: 100%; animation: completeIn 0.5s ease; }
@keyframes completeIn { from { opacity:0; transform: scale(0.9) translateY(20px); } to { opacity:1; transform: scale(1) translateY(0); } }
.complete-icon { font-size: 48px; margin-bottom: 12px; }
.complete-title { font-size: 22px; font-weight: 700; color: #1E1B4B; margin-bottom: 12px; }
.complete-stars { font-size: 36px; margin-bottom: 16px; letter-spacing: 8px; color: #F59E0B; }
.complete-stars .star-empty { color: #E5E7EB; }
.complete-stats { font-size: 14px; color: #6B7280; line-height: 1.8; margin-bottom: 20px; }
.complete-stats strong { color: #F59E0B; }
.complete-actions { display: flex; flex-direction: column; gap: 10px; }
.action-btn { padding: 14px 24px; font-size: 16px; font-weight: 600; border-radius: 12px; border: 2px solid #C7D2FE; background: #fff; color: #6366F1; cursor: pointer; transition: all 0.2s; }
.action-btn:active { transform: scale(0.97); }
.action-btn.primary { background: linear-gradient(135deg, #6366F1, #8B5CF6); border-color: transparent; color: #fff; }

/* Lottery */
.lottery-card { background: #fff; border-radius: 20px; padding: 32px 24px; text-align: center; box-shadow: 0 4px 20px rgba(99,102,241,0.1); max-width: 360px; margin: auto; width: 100%; animation: completeIn 0.5s ease; }
.lottery-title { font-size: 24px; font-weight: 700; color: #F59E0B; margin-bottom: 8px; }
.lottery-cost { font-size: 14px; color: #9CA3AF; margin-bottom: 4px; }
.lottery-cost strong { color: #F59E0B; }
.lottery-balance { font-size: 14px; color: #9CA3AF; margin-bottom: 20px; }
.lottery-balance strong { color: #F59E0B; font-size: 18px; }
.lottery-box { width: 120px; height: 120px; margin: 0 auto 16px; display: flex; align-items: center; justify-content: center; }
.lottery-gift { font-size: 72px; line-height: 1; transition: transform 0.3s; }
.lottery-gift.spinning { animation: giftSpin 1.2s cubic-bezier(0.4,0,0.2,1); }
.lottery-gift.opened { animation: giftOpen 0.5s ease forwards; }
@keyframes giftSpin { 0% { transform: scale(1) rotate(0); } 100% { transform: scale(1.3) rotate(0); } }
@keyframes giftOpen { 0% { transform: scale(1.3); } 50% { transform: scale(1.5); } 100% { transform: scale(1.1); } }
.lottery-result { min-height: 56px; margin-bottom: 16px; opacity: 0; transition: opacity 0.3s; }
.lottery-result.show { opacity: 1; }
.lottery-result .prize-name { font-size: 22px; font-weight: 700; color: #1E1B4B; margin-bottom: 4px; }
.lottery-result .prize-desc { font-size: 14px; color: #9CA3AF; }
.lottery-draw-btn { margin-bottom: 10px; width: 100%; }
.lottery-draw-btn:disabled { opacity: 0.4; cursor: default; }

/* Detail explanation steps */
.exp-step { margin-bottom: 10px; }
.exp-step:last-child { margin-bottom: 0; }
.exp-label { font-size: 13px; font-weight: 700; color: #B45309; margin-bottom: 3px; }
.exp-body { font-size: 14px; color: #78350F; line-height: 1.7; padding-left: 2px; }
.exp-body b { color: #D97706; }
.exp-highlight { display: inline-block; background: #FEF3C7; padding: 2px 8px; border-radius: 6px; font-weight: 700; margin: 4px 0; }

@media (max-width: 360px) { .problem-text { font-size: 15px; } .choice-btn { padding: 12px 14px; font-size: 14px; } }
@media (min-width: 500px) { .wp-main { max-width: 480px; margin: 0 auto; width: 100%; } }