:root {
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --light-color: #f8f9fa;
    --dark-color: #343a40;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: orange;
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --border-radius: 8px;
    --box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);

    --bg-color: var(--light-color);
    --text-color: var(--dark-color);
    --card-bg-color: #fff;
    --card-border-color: #ddd;
    --input-bg-color: #fff;
    --input-border-color: #ccc;
    --chat-bubble-bot-bg: #e9ecef;
    --chat-bubble-bot-text: var(--dark-color);
    --chat-bubble-user-bg: var(--primary-color);
    --chat-bubble-user-text: #fff;
    --header-border-color: #eee;
    --system-message-bg: #fff3cd;
    --system-message-text: #856404;
}

body.dark-mode {
    --primary-color: #0d6efd;
    --secondary-color: #adb5bd;
    --success-color: #198754;
    --danger-color: #dc3545;
    --warning-color: #fd7e14;

    --bg-color: #212529;
    --text-color: #f8f9fa;
    --card-bg-color: #343a40;
    --card-border-color: #495057;
    --input-bg-color: #495057;
    --input-border-color: #6c757d;
    --chat-bubble-bot-bg: #495057;
    --chat-bubble-bot-text: #f8f9fa;
    --chat-bubble-user-bg: var(--primary-color);
    --chat-bubble-user-text: #fff;
    --header-border-color: #495057;
    --system-message-bg: #332701;
    --system-message-text: #ffeb8f;
}

body {
    font-family: var(--font-family);
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 20px auto;
    padding: 20px;
    background-color: var(--card-bg-color);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    transition: background-color 0.3s;
}

header {
    text-align: center;
    margin-bottom: 15px;
    border-bottom: 1px solid var(--header-border-color);
    padding-bottom: 15px;
}

header h1 {
    color: var(--primary-color);
    margin: 0;
    font-size: 2em;
}

.toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--header-border-color);
    flex-wrap: wrap; 
    gap: 10px;
}

.toolbar-group { display: flex; gap: 10px; align-items: center; }

.toolbar button, .custom-file-upload, .toolbar a.btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 8px 15px;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.9em;
    transition: background-color 0.2s ease;
    text-decoration: none;
}
.toolbar button:hover, .custom-file-upload:hover, .toolbar a.btn:hover { background-color: #0056b3; }
body.dark-mode .toolbar button:hover, body.dark-mode .custom-file-upload:hover, body.dark-mode .toolbar a.btn:hover { background-color: #0b5ed7; }

.toolbar button#toggle-theme-button { background-color: var(--secondary-color); }
body.dark-mode .toolbar button#toggle-theme-button { background-color: #5c636a; }
.toolbar button#toggle-theme-button:hover { background-color: #545b62; }
body.dark-mode .toolbar button#toggle-theme-button:hover { background-color: #495057; }
.toolbar button:disabled {
    background-color: var(--secondary-color) !important;
    opacity: 0.65;
    cursor: not-allowed;
}
body.dark-mode .toolbar button:disabled {
     background-color: #52585d !important;
}

.api-key-container {
    display: flex;
    gap: 10px;
    align-items: center;
}

.api-key-container input {
    padding: 8px;
    border: 1px solid var(--input-border-color);
    border-radius: var(--border-radius);
    background-color: var(--input-bg-color);
    color: var(--text-color);
}

.main-content-area {
    display: flex;
    gap: 20px;
    flex-grow: 1;
    min-height: 0; 
}

.chat-and-loader-column {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 20px;
    min-width: 300px; 
}

.pdf-loader, .chat-area {
    padding: 15px;
    border: 1px solid var(--card-border-color);
    border-radius: var(--border-radius);
    background-color: var(--card-bg-color);
    transition: background-color 0.3s, border-color 0.3s;
}

.pdf-loader h2, .chat-area h2 {
    margin-top: 0;
    color: var(--primary-color);
    font-size: 1.3em;
    margin-bottom: 10px;
}

.file-input-wrapper {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px;
}
.file-input-wrapper input[type="file"] { display: none; }

#pdf-name {
    font-style: italic;
    color: var(--secondary-color);
    font-size: 0.9em;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
#pdf-status {
    font-weight: bold;
    margin-top: 5px;
    font-size: 0.9em;
}

.chat-display {
    height: 300px;
    overflow-y: auto;
    border: 1px solid var(--input-border-color);
    border-radius: var(--border-radius);
    padding: 10px;
    margin-bottom: 10px;
    background-color: var(--bg-color);
    line-height: 1.6;
    transition: background-color 0.3s, border-color 0.3s;
}

.chat-display .user-message, .chat-display .bot-message, .chat-display .system-message {
    margin-bottom: 10px;
    padding: 8px 12px;
    border-radius: var(--border-radius);
    max-width: 85%;
    word-wrap: break-word;
}
.chat-display .user-message {
    background-color: var(--chat-bubble-user-bg);
    color: var(--chat-bubble-user-text);
    margin-left: auto;
    text-align: right;
}
.chat-display .bot-message {
    background-color: var(--chat-bubble-bot-bg);
    color: var(--chat-bubble-bot-text);
    margin-right: auto;
}
.chat-display .bot-message strong { color: var(--primary-color); }

/* Markdown styling inside bot messages */
.chat-display .bot-message p { margin: 0 0 10px 0; }
.chat-display .bot-message p:last-child { margin: 0; }
.chat-display .bot-message pre { background: var(--dark-color); color: var(--light-color); padding: 10px; border-radius: 5px; overflow-x: auto; }
.chat-display .bot-message code { background: rgba(0,0,0,0.1); padding: 2px 4px; border-radius: 3px; }
body.dark-mode .chat-display .bot-message code { background: rgba(255,255,255,0.1); }

.chat-display .system-message {
    background-color: var(--system-message-bg);
    color: var(--system-message-text);
    text-align: center;
    font-style: italic;
    font-size: 0.9em;
}
.chat-display .system-message.error {
    background-color: #f8d7da;
    color: #721c24;
}

.question-input-area { display: flex; gap: 10px; }
#question-input {
    flex-grow: 1;
    padding: 10px;
    border: 1px solid var(--input-border-color);
    border-radius: var(--border-radius);
    font-size: 1em;
    resize: none;
    background-color: var(--input-bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}
#send-button {
    background-color: var(--success-color);
    color: white;
    border: none;
    padding: 0 20px;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.2s ease;
    display: flex; align-items: center; justify-content: center;
}
#send-button:hover { background-color: #1e7e34; }
body.dark-mode #send-button:hover { background-color: #157347; }
#send-button:disabled {
    background-color: var(--secondary-color) !important;
    opacity: 0.65;
    cursor: not-allowed;
}
body.dark-mode #send-button:disabled { 
    background-color: #52585d !important;
}

.loader {
    border: 3px solid #f3f3f3;
    border-top: 3px solid var(--primary-color);
    border-radius: 50%;
    width: 16px; height: 16px;
    animation: spin 1s linear infinite;
    display: none; margin-left: 8px;
}
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }

.pdf-viewer-container {
    flex: 1.5; 
    border: 1px solid var(--card-border-color);
    border-radius: var(--border-radius);
    overflow: hidden; 
    display: none; 
    flex-direction: column;
    min-width: 300px; 
}
.pdf-viewer-container.visible { display: flex; }
#pdf-iframe { width: 100%; height: 100%; border: none; }

footer {
    text-align: center;
    padding: 15px;
    background-color: var(--dark-color);
    color: var(--light-color);
    font-size: 0.8em;
    margin-top: 20px;
}
body.dark-mode footer { background-color: #1c1f23; }

@media (max-width: 992px) {
    .main-content-area { flex-direction: column; }
    .pdf-viewer-container.visible { min-height: 500px; }
}
@media (max-width: 768px) {
    .toolbar { flex-direction: column; align-items: stretch; }
    .toolbar-group { justify-content: center; width: 100%; flex-wrap: wrap; }
    .toolbar-group button, .toolbar-group .custom-file-upload { flex-grow: 1; }
    .question-input-area { flex-direction: column; }
    #send-button { width: 100%; padding: 12px; margin-top: 10px; }
    .chat-display { height: 250px; }
}