:root {
            --bg-color: #ededed;
            --header-bg: #f5f5f5;
            --text-color: #333333;
            --chat-bubble-bg: #95ec69;
            --chat-bubble-color: #000000;
            --bottom-bar-bg: #f7f7f7;
            --border-color: #e5e5e5;
            --record-btn-bg: #1890ff;
            --record-btn-color: #ffffff;
            --record-btn-active: #096dd9;
        }

        [data-theme="dark"] {
            --bg-color: #111111;
            --header-bg: #1e1e1e;
            --text-color: #ffffff;
            --chat-bubble-bg: #2ba245;
            --chat-bubble-color: #ffffff;
            --bottom-bar-bg: #1e1e1e;
            --border-color: #333333;
            --record-btn-bg: #177ddc;
            --record-btn-color: #ffffff;
            --record-btn-active: #0958d9;
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        html, body {
            height: 100%;
            width: 100%;
            overflow: hidden;
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
            background-color: var(--bg-color);
            color: var(--text-color);
            transition: background-color 0.3s, color 0.3s;
            position: relative;
        }

        .header {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 50px;
            background-color: var(--header-bg);
            border-bottom: 1px solid var(--border-color);
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0 15px;
            font-weight: bold;
            z-index: 10;
        }

        .theme-toggle {
            cursor: pointer;
            padding: 5px 10px;
            border: 1px solid var(--border-color);
            border-radius: 5px;
            background: transparent;
            color: var(--text-color);
            font-size: 14px;
        }

        .chat-container {
            position: absolute;
            top: 50px;
            bottom: 65px;
            left: 0;
            width: 100%;
            padding: 15px;
            overflow-y: auto;
            scroll-behavior: smooth;
        }

        .message-row {
            display: flex;
            justify-content: flex-end;
            margin-bottom: 20px;
        }

        .message-content {
            max-width: 75%;
            display: flex;
            flex-direction: column;
            align-items: flex-end;
        }

        .message-bubble {
            background-color: var(--chat-bubble-bg);
            color: var(--chat-bubble-color);
            padding: 10px 15px;
            border-radius: 8px 0 8px 8px;
            font-size: 16px;
            line-height: 1.5;
            word-wrap: break-word;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }

        .message-image {
            margin-top: 5px;
            border-radius: 5px;
            max-width: 100%;
            height: auto;
            border: 1px solid var(--border-color);
        }

        .bottom-bar {
            position: absolute;
            bottom: 0;
            left: 0;
            width: 100%;
            height: 65px;
            background-color: var(--bottom-bar-bg);
            border-top: 1px solid var(--border-color);
            padding: 10px 15px;
            display: flex;
            justify-content: center;
            align-items: center;
            z-index: 10;
        }

        .record-btn {
            width: 100%;
            height: 100%;
            background-color: var(--record-btn-bg);
            color: var(--record-btn-color);
            border: none;
            border-radius: 5px;
            font-size: 16px;
            font-weight: bold;
            cursor: pointer;
            user-select: none;
            -webkit-touch-callout: none;
            transition: background-color 0.2s;
        }

            .record-btn.recording {
                background-color: var(--record-btn-active);
            }

        .system-msg {
            text-align: center;
            font-size: 12px;
            color: #999;
            padding:20px;
            margin-bottom: 15px;
        }