/* ============================================================
   Design System
   ============================================================ */
:root {
    /* Colors — dark theme with violet accent */
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-tertiary: #1a1a26;
    --bg-hover: #22222f;
    --bg-active: #2a2a3a;

    --surface-user: #2d1f5e;
    --surface-assistant: #1a1a26;

    --text-primary: #e8e8ed;
    --text-secondary: #9494a8;
    --text-muted: #5e5e72;

    --accent: #8b5cf6;
    --accent-hover: #7c3aed;
    --accent-glow: rgba(139, 92, 246, 0.15);
    --accent-subtle: rgba(139, 92, 246, 0.08);

    --border: #2a2a3a;
    --border-subtle: #1e1e2e;

    --success: #34d399;
    --error: #f87171;
    --warning: #fbbf24;

    /* Typography */
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;

    /* Spacing */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);

    /* Layout */
    --sidebar-width: 280px;
}

/* ============================================================
   Reset & Base
   ============================================================ */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    overflow: hidden;
}

body {
    font-family: var(--font);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 14px;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* ============================================================
   Layout
   ============================================================ */
.app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* ============================================================
   Sidebar
   ============================================================ */
.sidebar {
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-subtle);
    display: flex;
    flex-direction: column;
    padding: 16px;
    gap: 16px;
    flex-shrink: 0;
    transition: transform var(--transition-base);
    z-index: 100;
}

.sidebar-header {
    padding: 4px 0 8px;
}

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

.logo-icon {
    font-size: 22px;
    background: linear-gradient(135deg, var(--accent), #c084fc);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: pulse-glow 3s ease-in-out infinite;
}

@keyframes pulse-glow {
    0%, 100% { filter: brightness(1); }
    50% { filter: brightness(1.3); }
}

.logo-text {
    font-size: 17px;
    font-weight: 700;
    letter-spacing: -0.3px;
    background: linear-gradient(135deg, var(--text-primary), var(--text-secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.new-chat-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 16px;
    background: var(--accent-subtle);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: var(--radius-md);
    color: var(--accent);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.new-chat-btn:hover {
    background: var(--accent-glow);
    border-color: rgba(139, 92, 246, 0.4);
    transform: translateY(-1px);
}

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

.model-selector {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.model-selector label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    color: var(--text-muted);
}

.model-selector select {
    padding: 10px 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 13px;
    cursor: pointer;
    transition: border-color var(--transition-fast);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M3 4.5l3 3 3-3' stroke='%239494a8' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 32px;
}

.model-selector select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.sidebar-footer {
    margin-top: auto;
    padding-top: 16px;
    border-top: 1px solid var(--border-subtle);
}

.status-indicator {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 12px;
    color: var(--text-muted);
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-muted);
    transition: background var(--transition-base);
}

.status-dot.online {
    background: var(--success);
    box-shadow: 0 0 6px rgba(52, 211, 153, 0.4);
}

.status-dot.error {
    background: var(--error);
}

/* ============================================================
   Chat Main
   ============================================================ */
.chat-main {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
    position: relative;
}

.chat-header {
    display: none; /* shown on mobile */
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-bottom: 1px solid var(--border-subtle);
    background: var(--bg-secondary);
}

.menu-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 4px;
}

.header-model {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
}

/* ============================================================
   Messages
   ============================================================ */
.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 24px 0;
    scroll-behavior: smooth;
}

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

.messages-container::-webkit-scrollbar-track {
    background: transparent;
}

.messages-container::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

.welcome-screen {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    text-align: center;
    padding: 40px 20px;
    animation: fadeIn 0.6s ease;
}

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

.welcome-icon {
    font-size: 48px;
    margin-bottom: 20px;
    background: linear-gradient(135deg, var(--accent), #c084fc, #818cf8);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: pulse-glow 3s ease-in-out infinite;
}

.welcome-screen h1 {
    font-size: 24px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.welcome-screen p {
    font-size: 14px;
    color: var(--text-secondary);
}

/* Message bubbles */
.message {
    padding: 4px 0;
    animation: messageIn 0.3s ease;
}

@keyframes messageIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.message-inner {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    gap: 12px;
}

.message-avatar {
    width: 32px;
    height: 32px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    flex-shrink: 0;
    margin-top: 4px;
}

.message.user .message-avatar {
    background: var(--surface-user);
    color: #c4b5fd;
}

.message.assistant .message-avatar {
    background: linear-gradient(135deg, var(--accent), #818cf8);
    color: white;
}

.message-content {
    flex: 1;
    min-width: 0;
}

.message-role {
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 4px;
    color: var(--text-secondary);
}

.message-text {
    font-size: 14px;
    line-height: 1.7;
    color: var(--text-primary);
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.message-text p {
    margin-bottom: 8px;
}

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

.message-text code {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    padding: 1px 5px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 12.5px;
}

.message-text pre {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 14px 16px;
    overflow-x: auto;
    margin: 8px 0;
}

.message-text pre code {
    background: none;
    border: none;
    padding: 0;
}

/* Typing indicator */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 8px 0;
}

.typing-indicator span {
    width: 6px;
    height: 6px;
    background: var(--text-muted);
    border-radius: 50%;
    animation: typingBounce 1.4s ease-in-out infinite;
}

.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }

@keyframes typingBounce {
    0%, 60%, 100% { transform: translateY(0); opacity: 0.4; }
    30% { transform: translateY(-6px); opacity: 1; }
}

/* ============================================================
   Input Area
   ============================================================ */
.input-area {
    padding: 0 24px 20px;
}

.input-wrapper {
    max-width: 720px;
    margin: 0 auto;
    display: flex;
    align-items: flex-end;
    gap: 8px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 8px 8px 8px 16px;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.input-wrapper:focus-within {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.input-wrapper textarea {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 14px;
    line-height: 1.5;
    resize: none;
    max-height: 160px;
    padding: 4px 0;
}

.input-wrapper textarea::placeholder {
    color: var(--text-muted);
}

.input-wrapper textarea:focus {
    outline: none;
}

.send-btn {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
    background: var(--accent);
    border: none;
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: all var(--transition-fast);
}

.send-btn:hover:not(:disabled) {
    background: var(--accent-hover);
    transform: scale(1.05);
}

.send-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.input-footer {
    max-width: 720px;
    margin: 6px auto 0;
    font-size: 11px;
    color: var(--text-muted);
    text-align: center;
}

/* ============================================================
   Welcome screen model selector
   ============================================================ */
.welcome-model-selector {
    margin-top: 20px;
    width: 100%;
    max-width: 300px;
}

.welcome-model-selector select {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 14px;
    cursor: pointer;
    transition: border-color var(--transition-fast);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M3 4.5l3 3 3-3' stroke='%239494a8' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    padding-right: 36px;
}

.welcome-model-selector select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

/* ============================================================
   Mobile header model selector
   ============================================================ */
.header-model-select {
    flex: 1;
    min-width: 0;
    padding: 6px 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath d='M3 4.5l3 3 3-3' stroke='%239494a8' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 10px center;
    padding-right: 28px;
}

.header-model-select:focus {
    outline: none;
    border-color: var(--accent);
}

/* ============================================================
   Sidebar overlay (mobile)
   ============================================================ */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    z-index: 99;
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        bottom: 0;
        transform: translateX(-100%);
    }

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

    .sidebar-overlay.open {
        display: block;
    }

    .chat-header {
        display: flex;
    }

    .messages-container {
        padding-top: 8px;
    }

    .message-inner {
        padding: 0 16px;
    }

    .input-area {
        padding: 0 12px 12px;
    }
}

/* ============================================================
   Login Overlay & Card
   ============================================================ */
.login-overlay {
    position: fixed;
    inset: 0;
    background: rgba(10, 10, 15, 0.85);
    backdrop-filter: blur(16px);
    display: none; /* Controlled via JS */
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 20px;
}

.login-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 40px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6);
    display: flex;
    flex-direction: column;
    gap: 24px;
    animation: cardSlideIn 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes cardSlideIn {
    from {
        transform: translateY(24px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.login-header {
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.login-header .logo-icon {
    font-size: 28px;
    background: linear-gradient(135deg, var(--accent), #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 8px;
}

.login-header h2 {
    font-size: 22px;
    font-weight: 700;
    color: var(--text-primary);
}

.login-header p {
    font-size: 13px;
    color: var(--text-secondary);
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.form-group label {
    font-size: 12px;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group input {
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 12px 16px;
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 14px;
    outline: none;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-group input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.error-message {
    color: #f87171;
    font-size: 13px;
    text-align: center;
    display: none;
    line-height: 1.4;
}

.submit-btn {
    background: var(--accent);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    padding: 14px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition-fast), transform var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.submit-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
}

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

.login-footer {
    text-align: center;
    font-size: 13px;
    color: var(--text-secondary);
}

.toggle-auth-btn {
    background: none;
    border: none;
    color: var(--accent);
    font-weight: 600;
    cursor: pointer;
    margin-left: 4px;
    padding: 0;
    transition: color var(--transition-fast);
}

.toggle-auth-btn:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}