/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
    /* Colors */
    --bg-primary: #0f0f0f;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #2a2a2a;
    --bg-hover: #2f2f2f;
    --bg-input: #1f1f1f;
    
    --text-primary: #ececec;
    --text-secondary: #b4b4b4;
    --text-tertiary: #8e8e8e;
    
    --accent-primary: #10a37f;
    --accent-hover: #0d8968;
    --accent-light: rgba(16, 163, 127, 0.1);
    
    --border-color: #3a3a3a;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-accent: linear-gradient(135deg, #10a37f 0%, #0d8968 100%);
    --gradient-glass: linear-gradient(135deg, rgba(255, 255, 255, 0.05) 0%, rgba(255, 255, 255, 0.02) 100%);
    
    /* Spacing */
    --sidebar-width: 280px;
    --header-height: 60px;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background: var(--bg-primary);
    color: var(--text-primary);
    overflow: hidden;
    height: 100vh;
    display: flex;
}

/* ===========================
   Sidebar Styles
   =========================== */
.sidebar {
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 100;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.logo-icon {
    width: 32px;
    height: 32px;
    color: var(--accent-primary);
    filter: drop-shadow(0 0 10px rgba(16, 163, 127, 0.3));
}

.logo-text {
    font-size: 24px;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.new-chat-btn {
    width: 100%;
    padding: 12px 16px;
    background: var(--gradient-accent);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.2s ease;
    box-shadow: var(--shadow-sm);
}

.new-chat-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.conversations-list {
    flex: 1;
    overflow-y: auto;
    padding: 12px;
}

.conversation-item {
    padding: 12px 16px;
    margin-bottom: 4px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
    background: var(--gradient-glass);
    backdrop-filter: blur(10px);
}

.conversation-item:hover {
    background: var(--bg-hover);
}

.conversation-item.active {
    background: var(--accent-light);
    border-left: 3px solid var(--accent-primary);
}

.conversation-title {
    font-size: 14px;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    flex: 1;
}

.delete-conversation-btn {
    background: none;
    border: none;
    color: var(--text-tertiary);
    cursor: pointer;
    padding: 4px;
    border-radius: 4px;
    opacity: 0;
    transition: all 0.2s ease;
}

.conversation-item:hover .delete-conversation-btn {
    opacity: 1;
}

.delete-conversation-btn:hover {
    color: #ef4444;
    background: rgba(239, 68, 68, 0.1);
}

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

.user-info {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 8px;
    border-radius: 8px;
    background: var(--gradient-glass);
}

.user-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--gradient-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

.user-name {
    font-size: 14px;
    font-weight: 500;
    color: var(--text-primary);
}

/* ===========================
   Main Content Styles
   =========================== */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.sidebar-toggle {
    position: absolute;
    top: 16px;
    left: 16px;
    z-index: 50;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
}

.sidebar-toggle:hover {
    background: var(--bg-hover);
    transform: scale(1.05);
}

.chat-container {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    scroll-behavior: smooth;
}

/* ===========================
   Welcome Screen
   =========================== */
.welcome-screen {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100%;
    padding: 40px 20px;
}

.welcome-content {
    max-width: 800px;
    text-align: center;
}

.welcome-logo {
    margin-bottom: 24px;
}

.welcome-logo-icon {
    width: 80px;
    height: 80px;
    color: var(--accent-primary);
    filter: drop-shadow(0 0 30px rgba(16, 163, 127, 0.4));
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

.welcome-title {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 16px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-subtitle {
    font-size: 18px;
    color: var(--text-secondary);
    margin-bottom: 48px;
}

.feature-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 40px;
}

.feature-card {
    background: var(--gradient-glass);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 24px;
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-primary);
}

.feature-icon {
    font-size: 36px;
    margin-bottom: 12px;
}

.feature-card h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.feature-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* ===========================
   Messages Styles
   =========================== */
.messages {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

.message {
    margin-bottom: 24px;
    animation: slideIn 0.3s ease;
}

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

.message-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 8px;
}

.message-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 14px;
}

.message.user .message-avatar {
    background: var(--gradient-primary);
    color: white;
}

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

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

.message-content {
    margin-left: 44px;
    padding: 16px;
    border-radius: 12px;
    line-height: 1.6;
    font-size: 15px;
}

.message.user .message-content {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.message.assistant .message-content {
    background: var(--gradient-glass);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 16px;
}

.typing-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--accent-primary);
    animation: typing 1.4s infinite;
}

.typing-dot:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.7;
    }
    30% {
        transform: translateY(-10px);
        opacity: 1;
    }
}

/* ===========================
   Input Area Styles
   =========================== */
.input-area {
    padding: 20px;
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

.input-container {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    gap: 12px;
    align-items: flex-end;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 12px;
    transition: all 0.2s ease;
}

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

.message-input {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 15px;
    font-family: var(--font-family);
    resize: none;
    outline: none;
    max-height: 200px;
    line-height: 1.5;
}

.message-input::placeholder {
    color: var(--text-tertiary);
}

.send-btn {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: none;
    background: var(--gradient-accent);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    flex-shrink: 0;
}

.send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.send-btn:not(:disabled):hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-md);
}

.send-btn:not(:disabled):active {
    transform: scale(0.95);
}

.input-hint {
    text-align: center;
    font-size: 12px;
    color: var(--text-tertiary);
    margin-top: 12px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

/* ===========================
   Scrollbar Styles
   =========================== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--bg-hover);
}

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        bottom: 0;
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .welcome-title {
        font-size: 32px;
    }
    
    .feature-cards {
        grid-template-columns: 1fr;
    }
}

/* ===========================
   Utility Classes
   =========================== */
.hidden {
    display: none !important;
}

.loading {
    pointer-events: none;
    opacity: 0.6;
}