:root {
    --primary-color: #58cc02;
    --primary-shadow: #58a700;
    --secondary-color: #1cb0f6; /* 蓝色用于输入模式 */
    --secondary-shadow: #1899d6;
    --bg-color: #f7f7f7;
    --text-color: #4b4b4b;
    --btn-radius: 16px;
}

* {
    box-sizing: border-box; /* 关键：防止padding撑大元素导致重叠 */
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: 'Nunito', 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

.container {
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    z-index: 2;
}

/* --- 按钮基础修复 --- */
.btn {
    background: white;
    border: 2px solid #e5e5e5;
    border-bottom: 5px solid #e5e5e5; /* 增加厚度 */
    border-radius: var(--btn-radius);
    padding: 12px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: transform 0.1s, border-bottom-width 0.1s;
    color: var(--text-color);
    text-align: center;
    user-select: none;
    margin-bottom: 0; /* 让Grid gap控制间距，移除默认margin */
    width: 100%;
    position: relative;
}

.btn:active {
    transform: translateY(3px);
    border-bottom-width: 2px;
}

.btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-shadow);
    color: white;
}

/* --- 设置页布局优化 --- */
.setup-header {
    background: white;
    padding: 20px;
    border-radius: 20px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05);
    margin-bottom: 25px;
}

.control-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.control-row label {
    font-weight: bold;
    font-size: 1rem;
}

/* 模式切换按钮组 */
.toggle-group {
    display: flex;
    gap: 10px;
}

.toggle-btn {
    border: 2px solid #e5e5e5;
    padding: 8px 15px;
    border-radius: 12px;
    background: #fff;
    cursor: pointer;
    font-size: 0.9rem;
    color: #999;
}

.toggle-btn.active {
    background: #ddf4ff;
    border-color: #1cb0f6;
    color: #1cb0f6;
    font-weight: bold;
}

.radio-btn {
    border: 2px solid #e5e5e5;
    padding: 8px 15px;
    border-radius: 12px;
    background: #fff;
    cursor: pointer;
    font-size: 0.9rem;
    color: #999;
}

.radio-btn.active {
    background: #ddf4ff;
    border-color: #1cb0f6;
    color: #1cb0f6;
    font-weight: bold;
}

/* 章节卡片网格 */
.chapter-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    padding-bottom: 40px;
}
@media (max-width: 500px) {
    .chapter-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 320px) {
    .chapter-grid { grid-template-columns: 1fr; }
}

.chapter-section-title {
    grid-column: 1 / -1;
    font-size: 0.9rem;
    color: #777;
    margin: 15px 0 5px 0;
    padding-bottom: 5px;
    border-bottom: 1px solid #ddd;
}

.chapter-card {
    background: white;
    border: 2px solid #e5e5e5;
    border-bottom: 5px solid #e5e5e5;
    border-radius: 16px;
    padding: 12px 8px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
}
.chapter-card:active {
    transform: translateY(4px);
    border-bottom-width: 1px;
}
.chapter-card h3 { margin: 8px 0 4px; font-size: 0.95rem; }
.chapter-card p { margin: 0; color: #888; font-size: 0.75rem; }
.chapter-icon { font-size: 1.8rem; display: block; }

/* --- 游戏区布局 --- */
.question-area {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 3.5rem; /* 字体加大 */
    font-weight: 800;
    margin: 20px 0;
    min-height: 150px;
}

/* 选项网格 */
.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px; /* 增加间距 */
    width: 100%;
    margin-bottom: 20px;
}

.btn-choice {
    font-size: 2rem;
    padding: 20px 0; /* 增加点击区域 */
    height: 100%;
}

/* 键盘布局 */
.keypad {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    width: 100%;
    margin-bottom: 20px;
}

/* 显示框 */
.display-box {
    border: 3px solid #e5e5e5;
    border-radius: 16px;
    height: 70px;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: bold;
    background: white;
    margin-bottom: 20px;
    color: #333;
}

/* --- 特效层 --- */
#effects-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1; /* 在背景之上，内容之下 */
    pointer-events: none;
}

/* 结算页表情 */
.result-emoji { font-size: 5rem; display: block; margin-bottom: 10px; animation: pop 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275); }
@keyframes pop { from { transform: scale(0); } to { transform: scale(1); } }

/* 反馈条 */
.feedback-overlay {
    position: fixed;
    bottom: 0; left: 0; right: 0;
    padding: 20px;
    text-align: center;
    transform: translateY(110%);
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 100;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 -4px 20px rgba(0,0,0,0.1);
}
.feedback-overlay.show { transform: translateY(0); }
.feedback-correct { background: #d7ffb8; color: #58a700; }
.feedback-wrong { background: #ffdfe0; color: #ea2b2b; }

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-3px); }
    75% { transform: translateX(3px); }
}

.countdown-warning { background: #ffc107 !important; }
.countdown-danger { 
    background: #ff4b4b !important; 
    animation: shake 0.2s ease-in-out infinite;
}