:root {
    --bg-primary: #1a1a1a;
    --bg-secondary: #242424;
    --bg-hover: #333333;
    --text-primary: #e8e8e8;
    --text-secondary: #a0a0a0;
    --accent: #7c7cff;
    --accent-soft: #5c5c9e;
    --border: #3a3a3a;
    --user-msg-bg: #2a2a3a;
    --ai-msg-bg: #1e1e1e;
    --thought-bg: #1a1a2e;
    --thought-border: #3e3e5e;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    font-size: 15px;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

.sidebar {
    width: 260px;
    background: var(--bg-secondary);
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border);
}

.sidebar-header { padding: 12px; }

.new-chat-btn {
    width: 100%;
    padding: 12px;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 14px;
    transition: background 0.2s;
}

.new-chat-btn:hover { background: var(--bg-hover); }

.sidebar-content { flex: 1; overflow-y: auto; padding: 8px; }

.sidebar-footer { padding: 12px; border-top: 1px solid var(--border); }

.user-info {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px;
    border-radius: 8px;
    cursor: pointer;
    transition: background 0.2s;
}

.user-info:hover { background: var(--bg-hover); }

.user-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
}

.chat-container { flex: 1; display: flex; flex-direction: column; max-width: 100%; }

.chat-header {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.chat-header h1 { font-size: 18px; font-weight: 500; }

.model-selector {
    padding: 6px 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text);
    font-size: 13px;
    cursor: pointer;
    transition: all 0.2s;
    outline: none;
}

.model-selector:hover {
    background: var(--bg-hover);
    border-color: var(--accent);
}

.model-selector:focus {
    border-color: var(--accent);
}

.header-actions { display: flex; gap: 16px; align-items: center; }

.usage-display {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    background: var(--bg-secondary);
    border-radius: 8px;
    font-size: 13px;
    font-weight: 500;
    border: 1px solid var(--border);
    cursor: help;
    transition: all 0.2s;
    color: #4ade80;
}

.usage-display:hover {
    background: var(--bg-hover);
}

.usage-icon {
    font-size: 14px;
}

.usage-text {
    white-space: nowrap;
}

.toggle-switch { display: flex; align-items: center; gap: 8px; cursor: pointer; user-select: none; }
.toggle-switch input { display: none; }

.toggle-slider {
    width: 40px;
    height: 20px;
    background: var(--border);
    border-radius: 10px;
    position: relative;
    transition: background 0.2s;
}

.toggle-slider::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    background: white;
    border-radius: 50%;
    top: 2px;
    left: 2px;
    transition: transform 0.2s;
}

.toggle-switch input:checked + .toggle-slider { background: #4ade80; }
.toggle-switch input:checked + .toggle-slider::after { transform: translateX(20px); }

.toggle-label { font-size: 14px; color: var(--text-secondary); }

.chat-messages { flex: 1; overflow-y: auto; padding: 24px; }

.welcome-section { max-width: 920px; margin: 0 auto; padding: 60px 20px; }
.welcome-section h2 { font-size: 32px; font-weight: 400; margin-bottom: 32px; text-align: center; }

.suggestion-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 12px; }

.suggestion-card {
    padding: 16px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s;
    text-align: left;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.suggestion-card:hover { background: var(--bg-hover); transform: translateY(-2px); }

.suggestion-icon { font-size: 20px; }
.suggestion-text { font-size: 14px; color: var(--text-secondary); }

.message {
    max-width: 920px;
    margin: 0 auto 28px;
    padding: 24px 28px;
    border-radius: 16px;
    animation: fadeIn 0.3s;
}

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

.message.user { 
    background: var(--user-msg-bg); 
    margin-left: auto;
    border: 1px solid var(--border);
}

.message.ai { 
    background: var(--ai-msg-bg);
    border: 1px solid var(--border);
}

.message-header { 
    display: flex; 
    align-items: center; 
    gap: 12px; 
    margin-bottom: 16px; 
    font-weight: 600; 
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.message-avatar {
    width: 32px;
    height: 32px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 700;
}

.message.user .message-avatar { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
.message.ai .message-avatar { background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%); }

.message-content { 
    font-size: 16px; 
    line-height: 1.8; 
    color: var(--text-primary);
    white-space: pre-wrap;
    word-wrap: break-word;
}

.message-content p {
    margin-bottom: 16px;
}

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

.thought-content {
    background: var(--thought-bg);
    border: 1px solid var(--thought-border);
    border-radius: 12px;
    padding: 16px 20px;
    margin-bottom: 16px;
    font-size: 13px;
    line-height: 1.7;
    color: var(--text-secondary);
}

.thought-content.collapsed .thought-body {
    display: none;
}

.thought-header { 
    display: flex; 
    align-items: center; 
    justify-content: space-between;
    gap: 8px; 
    font-weight: 600; 
    margin-bottom: 0;
    color: var(--accent);
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    user-select: none;
}

.thought-content:not(.collapsed) .thought-header {
    margin-bottom: 12px;
}

.toggle-icon {
    font-size: 10px;
    transition: transform 0.2s;
}

.thought-body {
    max-height: 300px;
    overflow-y: auto;
}

.loading-indicator { display: flex; gap: 4px; padding: 12px 0; }

.loading-dot {
    width: 8px;
    height: 8px;
    background: var(--accent);
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out both;
}

.loading-dot:nth-child(1) { animation-delay: -0.32s; }
.loading-dot:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}

.chat-input-container { padding: 20px 24px; border-top: 1px solid var(--border); }

.chat-input-wrapper {
    max-width: 920px;
    margin: 0 auto;
    display: flex;
    gap: 12px;
    align-items: flex-end;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 12px 16px;
    transition: border-color 0.2s;
}

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

#chatInput {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 15px;
    resize: none;
    outline: none;
    max-height: 200px;
    font-family: inherit;
}

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

.send-btn {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.send-btn:not(:disabled):hover { background: var(--bg-hover); color: var(--text-primary); }
.send-btn:not(:disabled) { color: var(--text-primary); background: var(--accent); }
.send-btn:disabled { cursor: not-allowed; opacity: 0.5; }

.input-footer { text-align: center; margin-top: 12px; }
.info-text { font-size: 11px; color: var(--text-secondary); opacity: 0.7; }

.token-usage {
    margin-top: 16px;
    padding: 10px 14px;
    background: var(--bg-secondary);
    border-radius: 10px;
    font-size: 11px;
    color: var(--text-secondary);
    display: flex;
    gap: 20px;
    border: 1px solid var(--border);
}

.token-usage span {
    display: flex;
    align-items: center;
    gap: 6px;
}

/* Typography for formatted content */
.message-content p {
    margin-bottom: 14px;
}

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

.message-content h2, .message-content h3, .message-content h4 {
    margin: 20px 0 12px;
    font-weight: 600;
    color: var(--text-primary);
}

.message-content h2 { font-size: 20px; }
.message-content h3 { font-size: 17px; }
.message-content h4 { font-size: 15px; color: var(--accent); }

.message-content ul {
    margin: 12px 0;
    padding-left: 24px;
}

.message-content li {
    margin-bottom: 8px;
    line-height: 1.7;
}

.message-content strong {
    font-weight: 600;
    color: var(--text-primary);
}

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

.message-content code {
    background: var(--bg-secondary);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'SF Mono', 'Fira Code', Consolas, monospace;
    font-size: 13px;
    border: 1px solid var(--border);
}

::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

/* Mobile Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -260px;
        top: 0;
        height: 100vh;
        z-index: 1000;
        transition: left 0.3s;
    }

    .sidebar.open {
        left: 0;
    }

    .chat-container {
        width: 100%;
    }

    .chat-header {
        padding: 12px 16px;
    }

    .chat-header h1 {
        font-size: 16px;
    }

    .header-left {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .model-selector {
        font-size: 12px;
        padding: 5px 10px;
    }

    .chat-messages {
        padding: 16px 12px;
    }

    .message {
        max-width: 100%;
        padding: 16px;
        margin-bottom: 20px;
    }

    .message-content {
        font-size: 15px;
    }

    .welcome-section {
        max-width: 100%;
        padding: 40px 16px;
    }

    .welcome-section h2 {
        font-size: 24px;
        margin-bottom: 24px;
    }

    .suggestion-cards {
        grid-template-columns: 1fr;
    }

    .chat-input-container {
        padding: 12px 16px;
    }

    .chat-input-wrapper {
        max-width: 100%;
        border-radius: 20px;
        padding: 10px 12px;
    }

    #chatInput {
        font-size: 16px;
    }

    .token-usage {
        flex-wrap: wrap;
        gap: 12px;
        font-size: 10px;
    }

    .message-content h2 { font-size: 18px; }
    .message-content h3 { font-size: 16px; }
    .message-content h4 { font-size: 14px; }

    .message-avatar {
        width: 28px;
        height: 28px;
        font-size: 11px;
    }

    .toggle-label {
        display: none;
    }

    .usage-display {
        padding: 5px 10px;
        font-size: 11px;
    }

    .usage-icon {
        font-size: 12px;
    }
}

@media (max-width: 480px) {
    .chat-header h1 {
        font-size: 14px;
    }

    .message {
        padding: 12px;
    }

    .message-content {
        font-size: 14px;
    }

    .welcome-section h2 {
        font-size: 20px;
    }

    .suggestion-card {
        padding: 12px;
    }

    .header-actions {
        gap: 8px;
    }
}