body {
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: var(--font-ui);
    overflow: hidden;
    transition: background-color var(--duration-normal) var(--ease-standard),
                color var(--duration-normal) var(--ease-standard);
}

#app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* --- Sidebar --- */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--surface-color);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    transition: background-color var(--duration-normal) var(--ease-standard),
                border-color var(--duration-normal) var(--ease-standard);
}

.sidebar-header {
    padding: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
}

/* --- Main Reading Zone --- */
.reading-zone {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    min-width: 0; /* Prevent flex blowout */
}

.content-stream {
    flex: 1;
    overflow-y: auto;
    padding: 64px 10% 120px 10%; /* 底部留白给播放器 */
    scroll-behavior: smooth;
}

/* 隐藏滚动条但保留功能 */
.content-stream::-webkit-scrollbar, .chat-stream::-webkit-scrollbar {
    width: 4px;
}

.content-stream::-webkit-scrollbar-thumb, .chat-stream::-webkit-scrollbar-thumb {
    background-color: var(--border-color);
    border-radius: 2px;
}

/* --- Minimal Player --- */
.minimal-player {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: var(--player-height);
    background-color: var(--bg-color);
    border-top: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    z-index: 10;
}