:root {
    /* Color Palette */
    --bg-main: #0B0F19;
    --bg-sidebar: rgba(15, 23, 42, 0.6);
    --bg-input: rgba(30, 41, 59, 0.5);
    --border-color: rgba(255, 255, 255, 0.08);
    --text-primary: #F8FAFC;
    --text-secondary: #94A3B8;
    --accent-color: #38BDF8;
    --accent-gradient: linear-gradient(135deg, #38BDF8 0%, #818CF8 100%);
    --user-msg-bg: rgba(56, 189, 248, 0.1);
    --bot-msg-bg: transparent;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-main);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    background-image: 
        radial-gradient(circle at 15% 50%, rgba(56, 189, 248, 0.03) 0%, transparent 50%),
        radial-gradient(circle at 85% 30%, rgba(129, 140, 248, 0.03) 0%, transparent 50%);
}

.app-container {
    display: flex;
    height: 100%;
    width: 100%;
}

/* --- Sidebar --- */
.sidebar {
    width: 260px;
    background: var(--bg-sidebar);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: var(--transition-smooth);
}

.sidebar-header {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo i {
    -webkit-text-fill-color: initial;
    color: var(--accent-color);
}

.new-chat-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    background: var(--accent-gradient);
    color: white;
    border: none;
    padding: 12px;
    border-radius: 8px;
    font-weight: 500;
    font-size: 0.95rem;
    cursor: pointer;
    transition: var(--transition-smooth);
    box-shadow: 0 4px 15px rgba(56, 189, 248, 0.2);
}

.new-chat-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(56, 189, 248, 0.3);
}

.new-chat-btn:active {
    transform: translateY(0);
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: 0 12px;
}

.history-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    margin-bottom: 10px;
    padding: 0 8px;
}

.chat-history {
    list-style: none;
}

.history-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px;
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition-fast);
    font-size: 0.9rem;
    margin-bottom: 4px;
}

.history-item:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
}

.history-item.active {
    background: rgba(56, 189, 248, 0.1);
    color: var(--text-primary);
    border: 1px solid rgba(56, 189, 248, 0.2);
}

.sidebar-footer {
    padding: 20px;
    border-top: 1px solid var(--border-color);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-primary);
    font-size: 0.95rem;
    cursor: pointer;
}

.avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
}

/* --- Main Chat Area --- */
.chat-main {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
}

.chat-header {
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-bottom: 1px solid var(--border-color);
    background: rgba(11, 15, 25, 0.8);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 10;
}

.model-selector {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    padding: 6px 12px;
    border-radius: 6px;
    transition: var(--transition-fast);
}

.model-selector:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
}

/* --- Messages Container --- */
.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 80px 20px 120px;
    display: flex;
    flex-direction: column;
    gap: 24px;
    scroll-behavior: smooth;
}

.messages-container::-webkit-scrollbar {
    width: 6px;
}

.messages-container::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
}

/* Welcome Screen */
.welcome-container {
    margin: auto;
    text-align: center;
    max-width: 500px;
    animation: fadeIn 0.8s ease forwards;
}

.welcome-icon {
    font-size: 3rem;
    margin-bottom: 20px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.welcome-container h1 {
    font-size: 2rem;
    margin-bottom: 12px;
    font-weight: 600;
}

.welcome-container p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    line-height: 1.5;
}

/* Message Bubbles */
.message {
    display: flex;
    gap: 20px;
    max-width: 800px;
    margin: 0 auto;
    width: 100%;
    animation: slideUp 0.3s ease forwards;
    opacity: 0;
}

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

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.user .message-avatar {
    background: rgba(255, 255, 255, 0.1);
}

.bot .message-avatar {
    background: var(--accent-gradient);
    color: white;
}

.message-content {
    flex: 1;
    font-size: 1rem;
    line-height: 1.6;
    color: var(--text-primary);
}

.message-content p {
    margin-bottom: 1rem;
}

.message-content p:last-child {
    margin-bottom: 0;
}

/* Code block styling */
.message-content pre {
    background: #000;
    padding: 16px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 12px 0;
    border: 1px solid var(--border-color);
}

.message-content code {
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.9rem;
}

/* Reasoning block */
.reasoning-block {
    background: rgba(255, 255, 255, 0.03);
    border-left: 3px solid var(--text-secondary);
    padding: 12px 16px;
    margin-bottom: 16px;
    border-radius: 0 8px 8px 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-style: italic;
    display: none; /* Hidden by default until content is added */
}

.reasoning-block.has-content {
    display: block;
}

.cursor {
    display: inline-block;
    width: 8px;
    height: 16px;
    background-color: var(--text-primary);
    vertical-align: middle;
    animation: blink 1s step-end infinite;
    margin-left: 2px;
}

@keyframes blink {
    0%, 100% { opacity: 1; }
    50% { opacity: 0; }
}

/* --- Input Area --- */
.input-container-wrapper {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    padding: 20px;
    background: linear-gradient(transparent, var(--bg-main) 30%);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.input-container {
    width: 100%;
    max-width: 800px;
    position: relative;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 12px 16px;
    display: flex;
    align-items: flex-end;
    gap: 12px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    transition: border-color var(--transition-fast);
}

.input-container:focus-within {
    border-color: rgba(56, 189, 248, 0.5);
    box-shadow: 0 8px 32px rgba(56, 189, 248, 0.1);
}

textarea {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.5;
    resize: none;
    max-height: 200px;
    outline: none;
    padding: 4px 0;
}

textarea::placeholder {
    color: var(--text-secondary);
}

#send-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition-fast);
    font-size: 1.1rem;
    flex-shrink: 0;
}

#send-btn:not(:disabled) {
    background: var(--accent-gradient);
    color: white;
}

#send-btn:not(:disabled):hover {
    transform: scale(1.05);
}

.footer-text {
    margin-top: 12px;
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-align: center;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: absolute;
        transform: translateX(-100%);
        z-index: 20;
        height: 100%;
    }
    
    .message {
        padding: 0 10px;
    }
}