/* --- CSS 变量定义 --- */
:root {
    /* 主题色 */
    --primary-color: #766aee;
    --primary-color-dark: #6659d6;
    --primary-color-focus-glow: rgba(118, 106, 238, 0.3);

    /* 字体与文本颜色 */
    --font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --text-color-light: #e0e0e0;
    --text-color-dark: #b0b0b0;
    --text-color-white: #ffffff;
    --text-color-placeholder: #a0a0a0;

    /* 背景色 */
    --bg-glass: rgba(20, 20, 25, 0.5);
    --bg-header-footer: rgba(0, 0, 0, 0.25);
    --bg-input: rgba(0, 0, 0, 0.3);
    --bg-assistant-message: rgba(44, 48, 53, 0.8);
    --bg-user-message-gradient: linear-gradient(135deg, rgba(118, 106, 238, 0.7), rgba(102, 78, 240, 0.8));
    --bg-select-option: #2a2a30;
    --bg-error: rgba(255, 82, 82, 0.7);

    /* 边框与阴影 */
    --border-color: rgba(255, 255, 255, 0.125);
    --border-color-input: rgba(255, 255, 255, 0.2);
    --shadow-main: 0 8px 32px 0 rgba(0, 0, 0, 0.37);

    /* 圆角 */
    --border-radius-main: 20px;
    --border-radius-message: 18px;
    --border-radius-input: 24px;
    --border-radius-small: 8px;
}

/* --- 基础与背景设置 --- */
body {
    background-image: url('image.png');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    font-family: var(--font-family);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

/* --- 聊天主容器 --- */
.chat-container {
    width: 100%;
    max-width: 800px;
    height: 95vh;
    max-height: 900px;
    background-color: var(--bg-glass);
    backdrop-filter: blur(5px) saturate(150%);
    -webkit-backdrop-filter: blur(5px) saturate(150%);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-main);
    box-shadow: var(--shadow-main);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    color: var(--text-color-light);
    transition: all 0.3s ease;
}

/* --- 聊天头部区域 --- */
.chat-header {
    padding: 18px 24px;
    background-color: var(--bg-header-footer);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0;
}

.chat-header h1 {
    font-size: 20px;
    font-weight: 700;
    margin: 0;
    color: var(--text-color-white);
    text-shadow: 0 0 5px rgba(255,255,255,0.3);
}

.model-selector label {
    font-size: 14px;
    color: var(--text-color-dark);
}

.model-selector select {
    padding: 6px 10px;
    border-radius: var(--border-radius-small);
    border: 1px solid var(--border-color-input);
    background-color: var(--bg-input);
    color: var(--text-color-white);
    font-size: 14px;
    cursor: pointer;
}
.model-selector select option {
    background: var(--bg-select-option);
}
.model-selector select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--primary-color-focus-glow);
}

/* --- 聊天消息显示窗口 --- */
.chat-window {
    flex-grow: 1;
    padding: 24px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.chat-window::-webkit-scrollbar {
    width: 6px;
}
.chat-window::-webkit-scrollbar-thumb {
    background-color: var(--border-color-input);
    border-radius: 3px;
}

/* --- 聊天消息本身 --- */
.message {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    max-width: 85%;
    line-height: 1.6;
    animation: message-fade-in 0.4s ease-out;
}

@keyframes message-fade-in {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.message-content {
    padding: 12px 16px;
    border-radius: var(--border-radius-message);
    font-size: 15px;
    white-space: pre-wrap;
    word-wrap: break-word;
    min-height: 1.6em;
}

.message-content img {
    max-width: 100%;
    border-radius: 10px;
    margin-top: 8px;
    display: block;
}

/* 用户发送的消息 */
.message.user {
    align-self: flex-end;
}

.message.user .message-content {
    background: var(--bg-user-message-gradient);
    color: var(--text-color-white);
    border-bottom-right-radius: 4px;
}

/* AI 助手的回复 */
.message.assistant .message-content {
    background-color: var(--bg-assistant-message);
    color: var(--text-color-light);
    border-bottom-left-radius: 4px;
}

.message.assistant.loading .message-content {
    animation: pulse 1.5s infinite;
}

@keyframes pulse {
    0% { background-color: var(--bg-assistant-message); }
    50% { background-color: rgba(60, 65, 72, 0.8); }
    100% { background-color: var(--bg-assistant-message); }
}

.message.assistant.error .message-content {
    background-color: var(--bg-error);
    color: var(--text-color-white);
    animation: none;
}

/* --- 底部聊天输入区域 --- */
.chat-input-area {
    padding: 16px 24px;
    border-top: 1px solid var(--border-color);
    background-color: var(--bg-header-footer);
    flex-shrink: 0;
}

.chat-form {
    display: flex;
    gap: 12px;
    align-items: center;
}

.chat-form input {
    flex-grow: 1;
    padding: 12px 16px;
    border: 1px solid var(--border-color-input);
    background-color: var(--bg-input);
    border-radius: var(--border-radius-input);
    font-size: 15px;
    color: var(--text-color-white);
}
.chat-form input::placeholder {
    color: var(--text-color-placeholder);
}
.chat-form input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--primary-color-focus-glow);
}

.chat-form button {
    padding: 12px;
    width: 48px;
    height: 48px;
    border: none;
    border-radius: 50%;
    font-size: 18px;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background-color 0.2s;
}

.chat-form button.upload-button {
    background-color: transparent;
    color: var(--text-color-dark);
    border: 1px solid var(--border-color-input);
}
.chat-form button.upload-button:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--text-color-white);
}

.chat-form button[type="submit"] {
    background-color: var(--primary-color);
    color: var(--text-color-white);
}
.chat-form button[type="submit"]:hover {
    background-color: var(--primary-color-dark);
}
.chat-form button[type="submit"]:disabled {
    background-color: #555;
    cursor: not-allowed;
}

/* --- 图片预览区域 --- */
.image-preview-container {
    padding: 0 24px 10px;
    display: flex;
    gap: 10px;
    align-items: center;
}
.image-preview-item {
    position: relative;
}
.image-preview-item img {
    width: 60px;
    height: 60px;
    border-radius: var(--border-radius-small);
    object-fit: cover;
}
.remove-image-btn {
    position: absolute;
    top: -5px;
    right: -5px;
    width: 20px;
    height: 20px;
    background-color: rgba(0,0,0,0.7);
    color: var(--text-color-white);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* --- 响应式设计：针对手机端的优化 --- */
@media (max-width: 768px) {
    body {
        align-items: flex-start;
        justify-content: flex-start;
    }

    .chat-container {
        width: 100%;
        height: 100vh;
        max-height: 100vh;
        border-radius: 0;
        box-shadow: none;
        border: none;
    }

    .chat-header { padding: 12px 16px; }
    .chat-header h1 { font-size: 18px; }
    .chat-window { padding: 16px; }
    .message-content { font-size: 14px; }
    .chat-input-area { padding: 8px 12px; }
    .chat-form { gap: 8px; }
    .chat-form input { padding: 10px 14px; }
    .chat-form button {
        width: 44px;
        height: 44px;
        font-size: 16px;
    }
    .image-preview-container { padding: 0 12px 8px; }
}

/* --- 针对非常窄的屏幕（如旧款手机）的微调 --- */
@media (max-width: 360px) {
    .chat-header h1 {
        display: none;
    }
    .chat-header {
        justify-content: center;
    }
}