/* --- GLOBAL STYLES & VARIABLES --- */
:root {
    --bg-primary: #121212;
    --bg-secondary: #1E1E1E;
    --bg-tertiary: #282828;
    --bg-hover: #333333;
    --text-primary: #E0E0E0;
    --text-secondary: #A0A0A0;
    --text-tertiary: #707070;
    --border-color: #383838;
    --accent-primary: #4A90E2;
    --accent-secondary: #50E3C2;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --border-radius: 12px;
    --transition-speed: 0.2s;
    --header-height: 56px;
    --input-height: 80px;
}

/* --- BASE & LAYOUT --- */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
}

.ai-page-body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    overflow: hidden;
}

.page-container {
    display: flex;
    height: 100vh;
}

/* --- SIDEBAR --- */
.sidebar {
    background-color: var(--bg-secondary);
    width: 280px;
    height: 100%;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
    transition: transform var(--transition-speed) ease-in-out;
    position: fixed;
    left: 0;
    top: 0;
    z-index: 1003;
    transform: translateX(-100%);
}

.sidebar-header, .sidebar-footer {
    padding: 1rem;
    flex-shrink: 0;
}

.sidebar-header {
    border-bottom: 1px solid var(--border-color);
}

.sidebar-footer {
    border-top: 1px solid var(--border-color);
}

.sidebar-content {
    flex-grow: 1;
    overflow-y: auto;
    padding: 1rem 0.5rem;
}

.new-chat-btn, .auth-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    width: 100%;
    padding: 0.75rem 1rem;
    border-radius: var(--border-radius);
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
}

.new-chat-btn:hover, .auth-btn:hover {
    background-color: var(--bg-hover);
    border-color: var(--text-secondary);
}

.history-title {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    padding: 0 0.5rem 0.5rem;
}

#chat-history-list {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.history-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-radius: 8px;
    transition: background-color var(--transition-speed) ease;
    position: relative;
}

.history-item:hover {
    background-color: var(--bg-tertiary);
}

.history-item .title-display, .history-item .title-input {
    flex-grow: 1;
    padding: 0.6rem 0.75rem;
    color: var(--text-secondary);
    text-decoration: none;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    cursor: pointer;
    border: none;
    background: transparent;
    font-family: var(--font-family);
    font-size: 0.9rem;
}

.history-item .title-display:hover {
    color: var(--text-primary);
}

.history-item .title-input {
    color: var(--text-primary);
    outline: none;
    border-bottom: 1px solid var(--accent-primary);
}

.history-item-actions {
    display: flex;
    align-items: center;
    position: absolute;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    background-color: var(--bg-tertiary);
    border-radius: 6px;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed) ease, visibility var(--transition-speed) ease;
}

.history-item:hover .history-item-actions {
    opacity: 1;
    visibility: visible;
}

.delete-chat-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.4rem;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color var(--transition-speed) ease;
}

.delete-chat-btn:hover {
    color: #ef4444;
}

/* --- MAIN CONTENT --- */
.ai-main {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    transition: margin-left var(--transition-speed) ease-in-out;
}

.ai-header {
    display: flex;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    background-color: rgba(18, 18, 18, 0.8);
    backdrop-filter: blur(10px);
    flex-shrink: 0;
    z-index: 1001;
    position: fixed;
    top: 0;
    padding: calc(0.75rem + env(safe-area-inset-top)) calc(1.5rem + env(safe-area-inset-right)) 0.75rem calc(1.5rem + env(safe-area-inset-left));
}

.menu-toggle {
    display: none; /* Hidden by default, shown on mobile */
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    margin-right: 1rem;
    padding: 0.5rem;
}

.ai-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
}

.active-model-display {
    margin-left: auto;
    font-size: 0.85rem;
    color: var(--text-secondary);
    background-color: var(--bg-secondary);
    padding: 0.25rem 0.75rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    transition: all var(--transition-speed) ease;
}

.chat-view-container {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    padding-top: var(--header-height);
    padding-bottom: var(--input-height);
    box-sizing: border-box;
    /* FIXED: Removed 'height: 100vh;' for better flexbox behavior */
}

.empty-chat-view {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 2rem;
    transition: opacity 0.5s ease;
}

.logo-arch {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
}

.welcome-message {
    font-size: 1.5rem;
    color: var(--text-secondary);
    max-width: 400px;
}

.chat-history-wrapper {
    flex-grow: 1;
    overflow-y: auto;
    padding: 1rem 0;
    display: none; /* Hidden by default */
}

.chat-history {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Show chat history when it has content */
.chat-view-container.has-history .empty-chat-view { display: none; }
.chat-view-container.has-history .chat-history-wrapper { display: block; }

/* --- MESSAGES --- */
.message-wrapper {
    display: flex;
    gap: 0.75rem;
    animation: messageFadeIn 0.4s ease-out;
}

.message-wrapper.user { justify-content: flex-end; }
.message-wrapper.bot { justify-content: flex-start; }

.avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 500;
    font-size: 0.85rem;
    flex-shrink: 0;
    margin-top: 4px;
}

.avatar.user-avatar { background-color: var(--accent-primary); color: white; }
.avatar.bot-avatar { background-color: var(--bg-tertiary); color: var(--accent-secondary); }

.message-content {
    max-width: 85%;
    display: flex;
    flex-direction: column;
}

.message-wrapper.user .message-content { align-items: flex-end; }
.message-wrapper.bot .message-content { align-items: flex-start; }

.message-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.4rem;
}

.message-wrapper.user .message-header {
    justify-content: flex-end;
}

.model-badge {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-tertiary);
    padding: 0.1rem 0.5rem;
    background-color: var(--bg-tertiary);
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.timestamp {
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

.message {
    padding: 0.75rem 1.25rem;
    border-radius: var(--border-radius);
    line-height: 1.6;
    word-break: break-word;
    color: var(--text-primary);
}

.message.user { background: var(--accent-primary); color: white; border-bottom-right-radius: 4px; }
.message.bot { background: var(--bg-secondary); border: 1px solid var(--border-color); border-bottom-left-radius: 4px; }

/* Markdown styles */
.message p { margin-bottom: 0.5rem; }
.message p:last-child { margin-bottom: 0; }
.message h1, .message h2, .message h3 { margin-top: 1rem; margin-bottom: 0.5rem; font-weight: 600; }
.message ul, .message ol { padding-left: 1.5rem; margin-bottom: 0.5rem; }
.message li { margin-bottom: 0.25rem; }
.message a { color: var(--accent-primary); text-decoration: none; }
.message a:hover { text-decoration: underline; }
.message code:not(pre code) { background-color: var(--bg-tertiary); padding: 0.2em 0.4em; margin: 0; font-size: 85%; border-radius: 6px; }
.message pre { background-color: var(--bg-primary); border: 1px solid var(--border-color); border-radius: 8px; margin: 1rem 0; position: relative; }
.message pre code { font-family: 'SF Mono', 'Fira Code', 'Consolas', monospace; font-size: 0.9rem; line-height: 1.5; display: block; padding: 1rem; overflow-x: auto; }
.copy-code-btn { position: absolute; top: 0.5rem; right: 0.5rem; background-color: var(--bg-hover); color: var(--text-secondary); border: 1px solid var(--border-color); border-radius: 6px; padding: 0.25rem 0.5rem; font-size: 0.8rem; cursor: pointer; opacity: 0; transition: opacity var(--transition-speed) ease, background-color var(--transition-speed) ease; }
.message pre:hover .copy-code-btn { opacity: 1; }
.copy-code-btn:hover { background-color: var(--border-color); color: var(--text-primary); }

.message-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0.5rem;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed) ease;
}

.message-content:hover .message-actions {
    opacity: 1;
    visibility: visible;
}

.action-btn {
    background: none;
    border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    padding: 0.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    transition: color var(--transition-speed) ease, background-color var(--transition-speed) ease;
}
.action-btn:hover { color: var(--text-primary); background-color: var(--bg-tertiary); }

/* --- INPUT AREA --- */
.chat-input-container {
    width: 100%;
    flex-shrink: 0;
    background: var(--bg-primary);
    position: fixed;
    bottom: 0;
    z-index: 1001;
    padding: 0.5rem env(safe-area-inset-right) calc(0.5rem + env(safe-area-inset-bottom)) env(safe-area-inset-left);
}

.suggestion-area {
    max-width: 800px;
    margin: 0 auto 0.75rem;
    padding: 0 1.5rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.suggestion-chip {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
    transition: background-color var(--transition-speed) ease, border-color var(--transition-speed) ease;
    font-size: 0.9rem;
}

.suggestion-chip:hover {
    background: var(--bg-tertiary);
    border-color: var(--text-secondary);
    color: var(--text-primary);
}

.chat-input-area {
    display: flex;
    align-items: flex-end;
    gap: 0.75rem;
    max-width: 800px;
    margin: 0 auto;
    padding: 0.5rem 0.75rem;
    border-radius: var(--border-radius);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    transition: border-color var(--transition-speed) ease;
}

.chat-input-area:focus-within {
    border-color: var(--accent-primary);
}

.model-selector-container { position: relative; }
.model-selector-btn {
    width: 38px;
    height: 38px;
    background: transparent;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
}
.model-selector-btn:hover { background-color: var(--bg-hover); color: var(--text-primary); }

.model-selector-menu {
    position: absolute;
    bottom: calc(100% + 0.5rem);
    left: 0;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    list-style: none;
    padding: 0.5rem;
    margin: 0;
    width: 180px;
    z-index: 1005;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: opacity var(--transition-speed) ease, transform var(--transition-speed) ease, visibility var(--transition-speed) ease;
}

.model-selector-menu.active { opacity: 1; visibility: visible; transform: translateY(0); }

.model-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.6rem;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: 6px;
    transition: background-color var(--transition-speed) ease, color var(--transition-speed) ease;
}
.model-option:hover { background-color: var(--bg-hover); color: var(--text-primary); }
.model-option[aria-selected="true"] { color: var(--accent-primary); font-weight: 500; }

#chat-input {
    flex-grow: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    resize: none;
    max-height: 200px;
    padding: 0.6rem 0.25rem;
    line-height: 1.5;
    overflow-y: auto;
}

#chat-input:focus { outline: none; }
#chat-input::placeholder { color: var(--text-tertiary); }

#send-btn {
    width: 38px;
    height: 38px;
    border-radius: 8px;
    border: none;
    background: var(--accent-primary);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition-speed) ease, transform var(--transition-speed) ease;
    flex-shrink: 0;
}

#send-btn:hover { background: #3a80d1; }
#send-btn:disabled { background: var(--bg-tertiary); color: var(--text-tertiary); cursor: not-allowed; transform: none; }

/* --- UTILITIES & ANIMATIONS --- */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed) ease, visibility var(--transition-speed) ease;
    z-index: 1002;
}
.overlay.active { opacity: 1; visibility: visible; }

@keyframes messageFadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* --- RESPONSIVE DESIGN --- */
@media (max-width: 768px) {
    .sidebar {
        width: 85vw;
        max-width: 320px;
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .menu-toggle {
        display: block;
    }

    .ai-header { 
        left: 0;
        width: 100%;
        padding-left: calc(1rem + env(safe-area-inset-left));
        padding-right: calc(1rem + env(safe-area-inset-right));
    }

    .chat-input-container {
        left: 0;
        width: 100%;
    }

    .chat-history, .suggestion-area {
        padding: 0 1rem;
    }

    .chat-input-area {
        margin: 0 1rem;
    }

    .message-content { max-width: 90%; }

    .active-model-display { display: none; }
}

@media (min-width: 769px) {
    .sidebar {
        position: static;
        transform: translateX(0);
    }

    .ai-header {
        left: 280px;
        width: calc(100% - 280px);
    }

    .chat-input-container {
        left: 280px;
        width: calc(100% - 280px);
    }

    .ai-main {
        width: calc(100% - 280px);
    }
}