/* ===================================================================
   1. GLOBAL VARIABLES & RESET
   ================================================================= */
:root {
    --bg-deep-dark: #0a192f;
    --bg-medium-dark: #172a46;
    --bg-light-dark: #2c3e50;
    --text-bright: #ccd6f6;
    --text-normal: #bdc3c7;
    --text-muted: #8892b0;
    --accent-primary: #64ffda;
    --accent-primary-darker: #52d3b4;
    --accent-primary-text: #0a192f;
    --border-color: #304a6e;
    --card-shadow: 0 10px 30px -15px rgba(2, 12, 27, 0.7);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-deep-dark);
    color: var(--text-normal);
    /* Vital for a full-screen chat app layout */
    height: 100vh; 
    height: 100dvh; /* Dynamic viewport height for mobile browsers */
    display: flex;
    flex-direction: column;
    overflow: hidden; /* Prevent body scroll, only chat window scrolls */
}

a { text-decoration: none; color: inherit; }

/* ===================================================================
   2. HEADER & NAVIGATION (Responsive)
   ================================================================= */
header {
    background-color: var(--bg-medium-dark);
    padding: 1rem 5%;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0; /* Header never shrinks */
    z-index: 100;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    flex-wrap: wrap;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--accent-primary);
}

nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
}

nav a {
    color: var(--text-normal);
    font-weight: 500;
    padding: 0.5rem 0;
    transition: color 0.3s;
    font-size: 0.95rem;
}

nav a:hover, nav a.active {
    color: var(--accent-primary);
    border-bottom: 2px solid var(--accent-primary);
}

/* ===================================================================
   3. MAIN CHAT LAYOUT
   ================================================================= */
main {
    flex-grow: 1; /* Takes up all remaining vertical space */
    display: flex;
    flex-direction: column;
    width: 100%;
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
    overflow: hidden; /* Contains the scrollable chat area */
}

.chat-container {
    background-color: var(--bg-medium-dark);
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    height: 100%; /* Fills the main area */
    overflow: hidden;
    position: relative;
}

/* --- Header Area --- */
.chat-header {
    padding: 15px 20px;
    background-color: var(--bg-light-dark);
    border-bottom: 1px solid var(--border-color);
    text-align: center;
    flex-shrink: 0;
}

.chat-header h1 {
    margin: 0;
    font-size: 1.25rem;
    color: var(--accent-primary);
}

.chat-header p {
    margin: 5px 0 0;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* --- Chat Window (Scrollable Area) --- */
.chat-window {
    flex-grow: 1;
    padding: 20px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 15px;
    scroll-behavior: smooth;
    background-color: rgba(10, 25, 47, 0.5); /* Subtle inner shadow */
}

/* Custom Scrollbar */
.chat-window::-webkit-scrollbar {
    width: 8px;
}
.chat-window::-webkit-scrollbar-track {
    background: var(--bg-deep-dark);
}
.chat-window::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

/* --- Messages --- */
.message {
    max-width: 80%;
    padding: 12px 16px;
    border-radius: 18px;
    line-height: 1.5;
    word-wrap: break-word;
    animation: fadeIn 0.3s ease-in;
    font-size: 0.95rem;
}

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

.bot-message {
    align-self: flex-start;
    background-color: var(--bg-light-dark);
    color: var(--text-bright);
    border-bottom-left-radius: 2px;
    border: 1px solid var(--border-color);
}

.user-message {
    align-self: flex-end;
    background-color: var(--accent-primary);
    color: var(--accent-primary-text);
    border-bottom-right-radius: 2px;
    font-weight: 500;
    box-shadow: 0 2px 10px rgba(100, 255, 218, 0.2);
}

/* --- Input Area --- */
.chat-input-area {
    display: flex;
    padding: 15px;
    background-color: var(--bg-light-dark);
    border-top: 1px solid var(--border-color);
    gap: 10px;
    flex-shrink: 0;
}

#user-input {
    flex-grow: 1;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 25px;
    background-color: var(--bg-deep-dark);
    color: var(--text-bright);
    font-size: 1rem; /* Keeps iOS from zooming in */
    transition: border-color 0.3s;
}

#user-input:focus {
    outline: none;
    border-color: var(--accent-primary);
}

.chat-input-area button {
    background-color: var(--accent-primary);
    color: var(--accent-primary-text);
    border: none;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s, background-color 0.2s;
    flex-shrink: 0;
}

.chat-input-area button:hover {
    background-color: var(--accent-primary-darker);
    transform: scale(1.05);
}

.chat-input-area button svg {
    width: 20px;
    height: 20px;
}

/* ===================================================================
   4. CONTENT FORMATTING (Markdown Support)
   ================================================================= */
.bot-message ul, .bot-message ol {
    margin: 8px 0 !important;
    padding-left: 20px !important;
    list-style-type: disc !important;
    display: block !important;
}

.bot-message li {
    margin-bottom: 4px !important;
    display: list-item !important;
}

.bot-message b, .bot-message strong {
    color: var(--accent-primary);
    font-weight: 700;
}

.bot-message i {
    opacity: 0.8;
    font-size: 0.85em;
    display: block;
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

/* ===================================================================
   5. RESPONSIVE MEDIA QUERIES
   ================================================================= */

/* Tablet & Mobile Navigation */
@media (max-width: 900px) {
    header { padding: 0.75rem 5%; }
    
    nav {
        flex-direction: column;
        gap: 0.75rem;
    }

    nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1rem;
        width: 100%;
    }
}

/* Mobile Phones (Full Screen Chat Experience) */
@media (max-width: 600px) {
    main {
        padding: 0; /* Remove padding to make it edge-to-edge */
        margin: 0;
        max-width: 100%;
        /* Calculate height carefully to fit between header and bottom */
        height: auto; 
    }

    .chat-container {
        border-radius: 0;
        border-left: none;
        border-right: none;
        border-bottom: none;
    }

    .chat-header {
        padding: 10px 15px;
    }

    .chat-window {
        padding: 15px;
    }

    .message {
        max-width: 85%; /* Slightly wider bubbles on small screens */
    }

    .chat-input-area {
        padding: 10px;
    }

    #user-input {
        padding: 10px 15px;
    }
    
    .chat-input-area button {
        width: 40px;
        height: 40px;
    }
}