/* 使用CSS变量，方便主题切换 */
:root {
    --bg-color: #f4f7f9;
    --text-color: #333333;
    --header-bg-color: #ffffff;
    --control-panel-bg: rgba(255, 255, 255, 0.9);
    --control-button-bg: #e0e0e0;
    --control-button-text: #333;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

body.dark-mode {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --header-bg-color: #242424;
    --control-panel-bg: rgba(30, 30, 30, 0.9);
    --control-button-bg: #444;
    --control-button-text: #e0e0e0;
    --shadow-color: rgba(0, 0, 0, 0.3);
}

/* 全局样式 */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    padding-bottom: 80px; /* 为底部的控制栏留出空间 */
}

/* 头部 */
.header {
    background-color: var(--header-bg-color);
    padding: 15px 20px;
    text-align: center;
    border-bottom: 1px solid var(--shadow-color);
    position: sticky;
    top: 0;
    z-index: 10;
    transition: background-color 0.3s;
}

#book-title {
    margin: 0;
    font-size: 1.2em;
}

/* 内容区域 */
.content-wrapper {
    height: calc(100vh - 61px); /* 100%视窗高度减去头部高度 */
    overflow-y: scroll;
    -webkit-overflow-scrolling: touch; /* 在iOS上实现更平滑的滚动 */
}

#content-display {
    padding: 20px;
    font-family: 'Georgia', 'serif';
    font-size: 16px; /* 默认字体大小，会被JS修改 */
    line-height: 1.8;
    white-space: pre-wrap;
    word-wrap: break-word;
    margin: 0 auto;
    max-width: 800px;
    transition: font-size 0.2s;
}

/* 控制栏 */
.controls {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background-color: var(--control-panel-bg);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    box-shadow: 0 -2px 10px var(--shadow-color);
    display: flex;
    justify-content: space-around;
    align-items: center;
    padding: 10px 0;
    height: 60px;
    box-sizing: border-box;
    z-index: 20;
    transition: background-color 0.3s;
}

.controls button {
    background-color: var(--control-button-bg);
    color: var(--control-button-text);
    border: none;
    border-radius: 8px;
    padding: 10px 20px;
    font-size: 1em;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
}

.controls button:active {
    transform: scale(0.95);
}