/* ========================================================================== */
/* 聊天区域主布局与头部 (Main Area Layout & Header) */
/* ========================================================================== */

.chat-area-content {
    display: flex;
    flex-direction: column;
    flex-grow: 1;
    min-height: 0;
}

.back-to-list-btn {
    display: none;
    margin-inline-end: var(--spacing-3);
    padding: var(--spacing-2);
    font-size: var(--font-size-icon-lg);
}

.chat-info-main {
    display: flex;
    flex-grow: 1;
    align-items: center;
}

.chat-avatar-main {
    width: var(--avatar-size-md);
    height: var(--avatar-size-md);
    margin-inline-end: var(--spacing-3);
    font-size: var(--font-size-xl);
}

.chat-details-main-header {
    display: flex;
    flex-direction: column;
}

.chat-title-main {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    transition: color var(--transition-duration-slow) ease-out;
}

.chat-status-main {
    position: relative;
    padding-left: 15px;
    min-height: 1em;
    line-height: var(--line-height-heading);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
}

.chat-status-main::before {
    content: '';
    position: absolute;
    left: 0;
    top: calc(50% - 4px);
    width: 8px;
    height: 8px;
    border-radius: var(--border-radius-circle);
    display: none;
    transition: background-color var(--transition-duration-slow) ease-out, box-shadow var(--transition-duration-slow) ease-out;
}

.chat-status-main.status-indicator-active::before {
    background-color: var(--success-bg);
    box-shadow: 0 0 4px var(--success-bg);
    display: inline-block;
}

.chat-status-main.status-indicator-inactive::before {
    background-color: var(--danger-bg);
    box-shadow: 0 0 4px var(--danger-bg);
    display: inline-block;
}

.chat-actions-main {
    display: flex;
    gap: var(--spacing-2);
}

/* ========================================================================== */
/* 消息容器与滚动 (Messages Container & Scrolling) */
/* ========================================================================== */

.chat-messages-container {
    display: flex;
    flex-direction: column;
    flex-grow: 1;
    min-height: 0;
    padding: var(--spacing-4);
    overflow-y: auto;
    overscroll-behavior-y: contain;
}

.chat-messages-container .loading-indicator-older-messages {
    display: none;
    padding: var(--spacing-3);
    text-align: center;
    width: 100%;
}

.chat-messages-container .loading-indicator-older-messages .spinner {
    display: inline-block;
    width: 24px;
    height: 24px;
    border: var(--border-width-thick) solid var(--surface-hover-bg);
    border-top-color: var(--brand-bg);
    border-radius: var(--border-radius-circle);
    animation: spin 1s linear infinite;
}

.scroll-to-latest-btn {
    position: absolute;
    bottom: 110px;
    right: 20px;
    z-index: var(--z-index-content);
    width: var(--icon-btn-size);
    height: var(--icon-btn-size);
    border-radius: var(--border-radius-circle);
    background-color: var(--brand-bg);
    color: var(--text-on-brand);
    border: none;
    box-shadow: 0 2px 5px rgba(var(--black-rgb), 0.2);
    cursor: pointer;
    font-size: var(--font-size-xxl);
    display: none;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition-duration-normal) ease-out, opacity var(--transition-duration-normal) ease-out, transform var(--transition-duration-normal) ease-out;
}

.scroll-to-latest-btn:hover {
    background-color: var(--brand-bg-dark);
}

/* ========================================================================== */
/* 欢迎页与消息气泡基础 (Welcome Screen & Base Message Bubble) */
/* ========================================================================== */

.no-chat-selected {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    width: 100%;
    margin: auto;
    color: var(--text-secondary);
    text-align: center;
}

.no-chat-selected .logo-placeholder {
    margin-bottom: 20px;
    font-size: 60px;
    color: var(--text-secondary);
}

.message {
    position: relative;
    max-width: var(--message-bubble-max-width);
    margin-bottom: 10px;
    padding: var(--spacing-2) var(--spacing-3);
    border: var(--border-width-standard) solid transparent;
    border-radius: var(--border-radius-md);
    box-shadow: var(--box-shadow-md);
    line-height: var(--line-height-base);
    overflow-wrap: break-word;
    word-wrap: break-word;
    transition: background-color var(--transition-duration-slow) ease-out, border-color var(--transition-duration-slow) ease-out, color var(--transition-duration-slow) ease-out;
}

/* ========================================================================== */
/* 消息类型与状态 (Message Types & States) */
/* ========================================================================== */

.message.sent {
    align-self: flex-end;
    border-bottom-right-radius: 2px;
    background: var(--sent-bg-color);
    color: var(--text-on-sent);
}

.message.received {
    align-self: flex-start;
    border-bottom-left-radius: 2px;
    background-color: var(--received-bg-color);
    color: var(--text-on-received);
}

.message.received.character-message {
    border-color: var(--character-message-border-color);
    background-color: var(--character-message-bg-color);
}

.message.system {
    align-self: center;
    padding: 5px 10px;
    border-radius: 15px;
    background-color: rgba(var(--surface-active-rgb), 0.8);
    box-shadow: none;
    color: var(--text-secondary);
    text-align: center;
    font-size: 12px;
}

/* ========================================================================== */
/* 消息内部结构 (Message Inner Structure) */
/* ========================================================================== */

.message .message-content-wrapper {
    display: flex;
    align-items: flex-end;
}

.message .message-content {
    flex-grow: 1;
    white-space: pre-wrap;
}

.message .message-sender {
    margin-bottom: var(--spacing-1);
    color: var(--brand-bg);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    transition: color var(--transition-duration-slow) ease-out;
}

.message .timestamp {
    margin-top: 5px;
    color: var(--text-secondary);
    text-align: end;
    font-size: var(--font-size-xs);
}

.message .message-content .streaming-cursor {
    display: inline-block;
    animation: blink-animation var(--animation-duration-blink) step-end infinite;
    color: var(--brand-bg);
    font-weight: var(--font-weight-bold);
    opacity: 1;
}

.message-inline-action-button {
    display: inline-block;
    padding: 3px 8px;
    margin-inline-start: var(--spacing-2);
    border: var(--border-width-standard) solid transparent;
    border-radius: 6px;
    background-color: rgba(var(--text-primary-rgb), 0.05);
    color: var(--brand-bg);
    text-decoration: none;
    cursor: pointer;
    font-weight: var(--font-weight-medium);
    font-size: 1em;
    line-height: 1.3;
    transition: background-color var(--transition-duration-normal) ease-out, border-color var(--transition-duration-normal) ease-out, color var(--transition-duration-normal) ease-out, box-shadow var(--transition-duration-normal) ease-out;
}

.message-inline-action-button:hover {
    background-color: rgba(var(--text-primary-rgb), 0.1);
    border-color: var(--brand-bg);
    color: var(--brand-bg-dark);
}

/* ========================================================================== */
/* 文件与媒体消息 (File & Media Messages) */
/* ========================================================================== */

.message .file-info {
    display: flex;
    align-items: center;
    padding: var(--spacing-2);
    border-radius: var(--border-radius-md);
    background-color: rgba(var(--text-primary-rgb), 0.03);
    transition: background-color var(--transition-duration-normal) ease-out;
}

.message .thumbnail-placeholder {
    flex-shrink: 0;
    max-width: 150px;
    max-height: 150px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-inline-end: var(--spacing-2);
    font-size: var(--font-size-icon-lg);
    background-color: var(--surface-hover-bg);
    border-radius: var(--border-radius-sm);
    overflow: hidden;
    position: relative;
}

.message .message-thumbnail {
    display: block;
    object-fit: cover;
    border-radius: var(--border-radius-sm);
}

.message .file-info .play-overlay-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 2em;
    color: rgba(var(--text-on-brand-rgb), 0.9);
    background-color: rgba(var(--black-rgb), 0.5);
    border-radius: var(--border-radius-circle);
    padding: 10px;
    display: none;
    pointer-events: none;
    transition: opacity var(--transition-duration-normal) ease-out;
}

.message .file-info:hover .play-overlay-icon {
    display: block;
    opacity: 1;
}

.message .file-name {
    font-weight: var(--font-weight-medium);
}

.message .file-meta {
    color: var(--text-secondary);
    font-size: 12px;
}

.message .download-btn,
.message .play-media-btn {
    margin-inline-start: var(--spacing-2);
    color: var(--brand-bg);
    font-size: var(--font-size-sm);
    text-decoration: none;
    background-color: var(--surface-hover-bg);
    padding: 5px 8px;
    border-radius: var(--border-radius-sm);
    border: var(--border-width-standard) solid var(--border-color);
    cursor: pointer;
    transition: background-color var(--transition-duration-normal) ease-out;
}

.message .download-btn:hover,
.message .play-media-btn:hover {
    background-color: var(--surface-active-bg);
}

.message .voice-message {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
}

.message .voice-message button.play-voice-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 30px;
    height: 30px;
    border: none;
    border-radius: var(--border-radius-circle);
    background: var(--brand-bg);
    color: var(--text-on-brand);
    cursor: pointer;
    font-size: var(--font-size-base);
    transition: background-color var(--transition-duration-normal) ease-out;
}

.message .voice-message button.play-voice-btn:hover {
    background-color: var(--brand-bg-dark);
}

.message .voice-duration {
    color: var(--text-secondary);
    font-size: 12px;
}

/* ========================================================================== */
/* TTS 语音控制 (TTS Controls) */
/* ========================================================================== */

.tts-control-container {
    display: inline-flex;
    align-items: center;
    flex-shrink: 0;
    margin-inline-start: var(--spacing-2);
    padding-top: 2px;
}

.tts-loading-spinner {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid var(--border-color);
    border-top-color: var(--brand-bg);
    border-radius: var(--border-radius-circle);
    animation: tts-spin 1s linear infinite;
}

.tts-play-button,
.tts-retry-button {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 20px;
    height: 20px;
    padding: 0;
    border: none;
    background: none;
    cursor: pointer;
    line-height: 1;
    font-size: 1.1em;
    transition: color var(--transition-duration-normal) ease-out;
}

.tts-play-button {
    color: var(--brand-bg);
}

.tts-play-button:hover {
    color: var(--brand-bg-dark);
}

.tts-retry-button {
    color: var(--danger-bg);
}

.tts-retry-button:hover {
    filter: brightness(0.8);
}

.tts-error-icon {
    color: var(--danger-bg);
    font-size: 1.1em;
}

/* ========================================================================== */
/* 拖放覆盖层 (Drag & Drop Overlay) */
/* ========================================================================== */

.drop-overlay {
    position: absolute;
    z-index: var(--z-index-dropdown);
    inset: 0;
    display: none;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    border: 3px dashed var(--surface-2-bg);
    border-radius: var(--border-radius-md);
    background-color: rgba(var(--brand-rgb), 0.7);
    color: var(--text-on-brand);
    pointer-events: none;
    transition: background-color var(--transition-duration-normal) ease-out, border-color var(--transition-duration-normal) ease-out;
}

.chat-area.drag-over .drop-overlay {
    display: flex;
}

.drop-overlay-text {
    font-size: var(--font-size-icon-lg);
    font-weight: var(--font-weight-bold);
    text-shadow: 1px 1px 2px rgba(var(--black-rgb), 0.5);
}

/* ========================================================================== */
/* 聊天输入区域 (Chat Input Area) */
/* ========================================================================== */

.chat-input-container {
    display: flex;
    flex-direction: column;
    padding: var(--spacing-3) var(--spacing-4);
    border-top: var(--border-width-standard) solid var(--border-color);
    background: var(--header-bg-color);
    position: relative;
}

.input-row {
    display: flex;
    align-items: flex-end;
    width: 100%;
}

#messageInput {
    border: var(--border-width-standard) solid var(--border-color);
    border-radius: var(--border-radius-pill);
    background-color: var(--input-bg-color);
    color: var(--text-primary); /* --- FIX: 新增 --- */
    flex-grow: 1;
    min-height: 24px;
    max-height: 120px;
    margin-inline: var(--spacing-1);
    padding: 10px 12px;
    overflow-y: auto;
    font-size: var(--font-size-md);
    line-height: var(--line-height-base);
    resize: none;
    transition: border-color var(--transition-duration-normal) ease-out, box-shadow var(--transition-duration-normal) ease-out;
}

#messageInput:hover {
    border-color: var(--border-color-strong);
}

#messageInput:focus {
    outline: none;
    border-color: var(--brand-bg);
    box-shadow: 0 0 0 var(--border-width-focus) rgba(var(--brand-rgb), 0.2);
}

#sendButtonMain {
    color: var(--brand-bg);
}

#filePreviewContainer,
#audioPreviewContainer {
    border-radius: var(--border-radius-md);
    background: var(--surface-active-bg);
    font-size: var(--font-size-sm);
}

.file-preview-item button,
.voice-message-preview button {
    margin-inline-start: 10px;
    padding: 3px var(--spacing-2);
    border: none;
    border-radius: var(--border-radius-sm);
    background: var(--danger-bg);
    cursor: pointer;
    color: var(--text-on-danger);
    font-size: 12px;
    transition: background-color var(--transition-duration-normal) ease-out;
}

.file-preview-item button:hover,
.voice-message-preview button:hover {
    background-color: var(--danger-bg-dark);
}

.file-preview-item,
.voice-message-preview {
    display: flex;
    align-items: center;
    padding: 5px var(--spacing-2);
}

.voice-message-preview .btn-play-preview {
    background: var(--success-bg);
    color: var(--text-on-success);
}

.voice-message-preview .btn-play-preview:hover {
    background-color: var(--success-bg-dark);
}

#voiceButtonMain .audio-timer-indicator {
    position: absolute;
    inset-block-end: 35px;
    inset-inline-start: 50%;
    padding: 2px 5px;
    border-radius: 3px;
    background-color: rgba(var(--black-rgb), 0.7);
    color: var(--text-on-brand);
    font-size: 10px;
    white-space: nowrap;
    transform: translateX(-50%);
}

/* ========================================================================== */
/* 截图与提及功能 (Screenshot & Mention Features) */
/* ========================================================================== */

.screenshot-options {
    position: absolute;
    bottom: calc(100% + 5px);
    right: 0;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-1);
    padding: var(--spacing-2);
    border: var(--border-width-standard) solid var(--border-color);
    border-radius: var(--border-radius-md);
    background-color: var(--surface-2-bg);
    box-shadow: var(--box-shadow-md);
    z-index: var(--z-index-content);
    opacity: 0;
    transform: translateY(10px);
    visibility: hidden;
    transition: opacity var(--transition-duration-normal) ease-out, transform var(--transition-duration-normal) ease-out, visibility 0s linear var(--transition-duration-normal);
}

.screenshot-options.show {
    opacity: 1;
    transform: translateY(0);
    visibility: visible;
    transition-delay: 0s;
}

.screenshot-option-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-1);
    padding: var(--spacing-2);
    border: none;
    border-radius: var(--border-radius-sm);
    background-color: transparent;
    color: var(--text-color);
    text-align: left;
    font-size: var(--font-size-base);
    cursor: pointer;
    white-space: nowrap;
    transition: background-color var(--transition-duration-normal) ease-out;
}

.screenshot-option-btn:hover {
    background-color: var(--surface-hover-bg);
}

.ai-mention-suggestions {
    position: absolute;
    left: 15px;
    right: 15px;
    background-color: var(--surface-2-bg);
    border-radius: var(--border-radius-md) var(--border-radius-md) 0 0;
    box-shadow: 0 -4px 12px rgba(var(--black-rgb), 0.1);
    max-height: 220px;
    overflow-y: auto;
    z-index: var(--z-index-modal);
    padding: 6px;
    opacity: 0;
    transform: translateY(10px);
    transform-origin: bottom center;
    visibility: hidden;
    transition: opacity var(--transition-duration-fast) ease-out, transform var(--transition-duration-fast) ease-out, visibility 0s linear var(--transition-duration-fast);
}

.ai-mention-suggestions[style*="display: block"] {
    opacity: 1;
    transform: translateY(0);
    visibility: visible;
    transition-delay: 0s;
}

.mention-suggestion-item {
    display: flex;
    align-items: center;
    padding: var(--spacing-2);
    border-radius: 6px;
    cursor: pointer;
    transition: background-color var(--transition-duration-fast) ease-in-out;
    overflow: hidden;
}

.mention-suggestion-item:hover {
    background-color: var(--surface-hover-bg);
}

.mention-suggestion-avatar {
    width: var(--avatar-size-sm);
    height: var(--avatar-size-sm);
    border-radius: var(--border-radius-circle);
    margin-right: var(--spacing-3);
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: var(--font-weight-medium);
    font-size: var(--font-size-base);
    color: var(--text-on-brand);
    background-color: var(--brand-bg);
    overflow: hidden;
}

.mention-suggestion-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.mention-suggestion-name {
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-medium);
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* ========================================================================== */
/* 特殊状态与修饰符 (Special States & Modifiers) */
/* ========================================================================== */

.chat-header-main.character-active .chat-title-main {
    color: var(--character-title-color);
}

.chat-header-main.character-active .chat-avatar-main {
    background-color: var(--character-avatar-bg);
    color: var(--character-avatar-text-color);
}

.message.received.character-message .message-sender {
    color: var(--character-message-sender-color);
}

.message.system.thinking .message-content {
    color: var(--text-secondary);
    font-style: italic;
}

#voiceButtonMain {
    position: relative;
}

#voiceButtonMain.recording {
    color: var(--danger-bg);
}

#voiceButtonMain.recording::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: var(--border-radius-circle);
    box-shadow: 0 0 0 0 rgba(var(--accent-danger-rgb), 0.7);
    animation: pulse var(--animation-duration-pulse) infinite;
    z-index: -1;
}

.tts-play-button.playing::after {
    content: "❚❚";
    font-size: 0.8em;
}

.tts-play-button:not(.playing)::after {
    content: "▶";
    font-size: 0.9em;
}

.message.retracted .message-content {
    font-style: italic;
    color: var(--text-secondary);
}

.chat-info-main.clickable-chat-header {
    cursor: pointer;
}

.chat-info-main.clickable-chat-header:hover .chat-avatar-main {
    filter: brightness(0.95);
}

.message.sticker .file-info {
    cursor: default !important;
    background-color: transparent;
    padding: 0;
}

.message.sticker .file-info .thumbnail-placeholder {
    max-width: 120px;
    max-height: 120px;
    background-color: transparent;
}

.message .download-file-btn {
    margin-inline-start: var(--spacing-2);
    color: var(--brand-bg);
    font-size: var(--font-size-sm);
    text-decoration: none;
    background-color: var(--surface-hover-bg);
    padding: 5px 8px;
    border-radius: var(--border-radius-sm);
    border: var(--border-width-standard) solid var(--border-color);
    cursor: pointer;
    transition: background-color var(--transition-duration-normal) ease-out;
}

/* ========================================================================== */
/* 响应式设计 (Responsive Design) */
/* ========================================================================== */

@media screen and (max-width: 768px) {
    .back-to-list-btn {
        display: block;
    }

    .chat-details-main-header {
        display: none;
    }

    #messageInput {
        line-height: 1;
        padding: 5px 10px;
    }
}