:root {
    /* Dynamic Mesh Gradient Core Colors */
    --bg-base: #1a1917;
    --mesh-color-1: rgba(217, 119, 87, 0.15); /* Claude Orange */
    --mesh-color-2: rgba(138, 134, 124, 0.2); /* Neutral Sand */
    --mesh-color-3: rgba(217, 119, 87, 0.1); 
    
    --text-primary: #e5e1d8;
    --text-secondary: #a39f96;
    
    /* Glassmorphism Tokens */
    --glass-bg: rgba(26, 25, 23, 0.6);
    --glass-border: rgba(255, 255, 255, 0.08);
    --glass-hover: rgba(255, 255, 255, 0.12);
    --glass-blur: blur(24px);
    
    --input-bg: rgba(42, 40, 37, 0.7);
    --input-border-focus: rgba(217, 119, 87, 0.4);
    
    --accent: #d97757;
    --avatar-bg: #e5e1d8;
    --avatar-text: #211f1c;
    
    --msg-user-bg: rgba(255, 255, 255, 0.05);
    --msg-assistant-bg: transparent;
    
    --code-bg: rgba(0, 0, 0, 0.3);
}

body.light-mode {
    --bg-base: #f7f6f3;
    --mesh-color-1: rgba(217, 119, 87, 0.12);
    --mesh-color-2: rgba(138, 134, 124, 0.15);
    --mesh-color-3: rgba(217, 119, 87, 0.08);
    
    --text-primary: #211f1c;
    --text-secondary: #6e6a62;
    
    --glass-bg: rgba(255, 255, 255, 0.65);
    --glass-border: rgba(0, 0, 0, 0.08);
    --glass-hover: rgba(0, 0, 0, 0.05);
    --glass-blur: blur(24px);
    
    --input-bg: rgba(255, 255, 255, 0.8);
    --input-border-focus: rgba(217, 119, 87, 0.5);
    
    --accent: #c45d3e;
    --avatar-bg: #211f1c;
    --avatar-text: #f5f4f1;
    
    --msg-user-bg: rgba(0, 0, 0, 0.03);
    
    --code-bg: rgba(0, 0, 0, 0.05);
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-base);
    color: var(--text-primary);
    height: 100vh;
    height: 100dvh;
    display: flex;
    overflow: hidden;
    position: relative;
    transition: background-color 0.4s ease, color 0.4s ease;
}

/* Ambient Mesh Background */
body::before {
    content: "";
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    z-index: -1;
    background: 
        radial-gradient(circle at 15% 50%, var(--mesh-color-1) 0%, transparent 40%),
        radial-gradient(circle at 85% 30%, var(--mesh-color-2) 0%, transparent 40%),
        radial-gradient(circle at 50% 80%, var(--mesh-color-3) 0%, transparent 50%);
    transition: background 0.6s ease;
    filter: blur(40px);
}

/* Sidebar (Glass) */
.sidebar {
    width: 64px;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border-right: 1px solid var(--glass-border);
    transition: background 0.4s ease, border-color 0.4s ease;
    z-index: 10;
}

.sidebar-top, .sidebar-bottom {
    display: flex;
    flex-direction: column;
    gap: 16px;
    align-items: center;
}

.icon-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
}

.icon-btn:hover {
    background-color: var(--glass-hover);
    color: var(--text-primary);
    transform: translateY(-1px);
}

.profile-btn {
    background: none;
    border: none;
    cursor: pointer;
    transition: transform 0.2s;
}

.profile-btn:hover {
    transform: scale(1.05);
}

.profile-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background-color: var(--avatar-bg);
    color: var(--avatar-text);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 15px;
    transition: all 0.4s ease;
}

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

/* Top Nav (Glass) */
.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 28px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 5;
}

.nav-left {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 500;
}

.logo {
    color: var(--text-primary);
    display: flex;
    align-items: center;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 14px;
}

.plan-text {
    color: var(--text-secondary);
}

.upgrade-btn {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: 6px 14px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 13px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.upgrade-btn:hover {
    background: var(--glass-hover);
    border-color: rgba(255,255,255,0.2);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.header-profile {
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: color 0.2s;
}
.header-profile:hover {
    color: var(--text-primary);
}

/* Chat Container */
.chat-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding-bottom: 10vh;
    overflow: hidden;
}

.chat-container.active-chat {
    justify-content: space-between;
    padding-top: 80px;
    padding-bottom: 40px;
}

.greeting-wrapper {
    margin-bottom: 36px;
    text-align: center;
}

.greeting {
    font-family: 'Playfair Display', serif;
    font-size: 36px;
    font-weight: 500;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 12px;
    justify-content: center;
    letter-spacing: -0.5px;
}

.asterisk {
    color: var(--accent);
    font-size: 40px;
    line-height: 1;
    filter: drop-shadow(0 0 12px rgba(217, 119, 87, 0.3));
}

/* Input Section (Glass) */
.input-section {
    width: 100%;
    max-width: 680px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    flex-shrink: 0;
    padding: 0 20px;
}

.input-box {
    background: var(--input-bg);
    backdrop-filter: var(--glass-blur);
    border-radius: 20px;
    padding: 14px 18px;
    border: 1px solid var(--glass-border);
    display: flex;
    flex-direction: column;
    gap: 12px;
    transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.05);
}

.input-box:focus-within {
    border-color: var(--input-border-focus);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1), 0 0 0 4px rgba(217, 119, 87, 0.08);
}

.input-top {
    display: flex;
}

textarea {
    width: 100%;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 16px;
    line-height: 1.5;
    resize: none;
    outline: none;
    padding: 4px 0;
    max-height: 200px;
    overflow-y: auto;
}

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

.input-bottom {
    display: flex;
    justify-content: flex-end;
    align-items: center;
}

.add-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 6px;
    border-radius: 8px;
    transition: all 0.2s;
}

.add-btn:hover {
    background-color: var(--glass-hover);
    color: var(--text-primary);
}

.input-controls {
    display: flex;
    align-items: center;
    gap: 8px;
}

.model-selector {
    display: flex;
    align-items: center;
    gap: 6px;
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    padding: 6px 12px;
    border-radius: 8px;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    transition: all 0.2s;
}

.model-selector:hover {
    background-color: var(--glass-hover);
    color: var(--text-primary);
    border-color: rgba(255,255,255,0.15);
}

.mic-btn, .settings-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 8px;
    border-radius: 8px;
    transition: all 0.2s;
}

.mic-btn:hover, .settings-btn:hover {
    background-color: var(--glass-hover);
    color: var(--text-primary);
}

/* Suggestion Chips (Glass) */
.suggestion-chips {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.chip {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    color: var(--text-secondary);
    padding: 10px 18px;
    border-radius: 100px;
    font-size: 13.5px;
    font-family: inherit;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0,0,0,0.02);
}

.chip:hover {
    background: var(--glass-hover);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0,0,0,0.06);
}

.chip svg {
    color: var(--text-secondary);
    transition: color 0.3s;
}

.chip:hover svg {
    color: var(--text-primary);
}

/* Chat History */
.chat-history {
    width: 100%;
    max-width: 840px;
    flex: 1;
    min-height: 0;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 24px;
    padding: 0 24px 24px 24px;
    margin-bottom: 24px;
    scroll-behavior: smooth;
}

/* Hide scrollbar for a cleaner look */
.chat-history::-webkit-scrollbar {
    width: 6px;
}
.chat-history::-webkit-scrollbar-thumb {
    background-color: var(--glass-border);
    border-radius: 10px;
}

.message {
    display: flex;
    flex-direction: column;
    max-width: 85%;
    line-height: 1.65;
    font-size: 15.5px;
    position: relative;
    margin-bottom: 24px;
}

.message.user {
    align-self: flex-end;
    background: var(--msg-user-bg);
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    padding: 14px 20px;
    border-radius: 20px;
    border-bottom-right-radius: 4px;
    color: var(--text-primary);
    box-shadow: 0 4px 12px rgba(0,0,0,0.03);
}

.reply-indicator {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 11px;
    color: var(--text-secondary);
    margin-bottom: 6px;
    padding-bottom: 6px;
    border-bottom: 1px solid var(--glass-border);
    opacity: 0.8;
}

.message.assistant {
    align-self: flex-start;
    padding: 14px 20px;
    background: var(--msg-assistant-bg);
}

/* Markdown formatting */
.message pre {
    background: var(--code-bg);
    backdrop-filter: blur(8px);
    padding: 16px;
    border-radius: 12px;
    overflow-x: auto;
    margin: 12px 0;
    border: 1px solid var(--glass-border);
}
.message code {
    font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
    font-size: 0.9em;
    background: var(--code-bg);
    padding: 3px 6px;
    border-radius: 6px;
}
.message pre code {
    background: transparent;
    padding: 0;
}
.message p {
    margin-bottom: 12px;
}
.message p:last-child {
    margin-bottom: 0;
}

/* History Drawer (Glass) */
.history-drawer {
    position: absolute;
    top: 0;
    left: -320px; /* Hidden state */
    width: 280px;
    height: 100%;
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border-right: 1px solid var(--glass-border);
    transition: left 0.4s cubic-bezier(0.2, 0, 0, 1);
    z-index: 9; 
    padding-left: 64px; 
    display: flex;
    flex-direction: column;
}

.history-drawer.open {
    left: 0;
}

.drawer-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 24px 20px 24px;
    border-bottom: 1px solid var(--glass-border);
}

.drawer-header h3 {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: 0.5px;
}

.close-drawer-btn {
    font-size: 24px;
    width: 32px;
    height: 32px;
}

.drawer-content {
    flex: 1;
    overflow-y: auto;
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.drawer-content::-webkit-scrollbar {
    width: 4px;
}
.drawer-content::-webkit-scrollbar-thumb {
    background-color: var(--glass-border);
    border-radius: 10px;
}

.empty-history {
    color: var(--text-secondary);
    font-size: 13px;
    text-align: center;
    margin-top: 40px;
}

.history-item {
    background: transparent;
    border: none;
    text-align: left;
    padding: 12px 16px;
    border-radius: 12px;
    color: var(--text-primary);
    font-size: 13.5px;
    cursor: pointer;
    transition: all 0.2s ease;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    border: 1px solid transparent;
}

.history-item:hover {
    background: var(--glass-hover);
    border-color: var(--glass-border);
}

.copy-msg-btn {
    opacity: 0;
    visibility: hidden;
    position: absolute;
    bottom: -32px;
    align-items: center;
    gap: 6px;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 12px;
    cursor: pointer;
    padding: 6px 12px;
    border-radius: 6px;
    transition: all 0.2s ease;
}

.message.user .copy-msg-btn {
    right: 0;
}

.message.assistant .copy-msg-btn {
    left: 0;
}

.copy-msg-btn:hover {
    background: var(--glass-hover);
    color: var(--text-primary);
}

.message:hover .copy-msg-btn {
    opacity: 1;
    visibility: visible;
}

.drawer-search { padding: 10px 16px; border-bottom: 1px solid var(--border-color); }
.drawer-search input { width: 100%; padding: 8px 12px; border-radius: 6px; border: 1px solid var(--border-color); background: var(--glass-bg); color: var(--text-primary); font-size: 14px; outline: none; box-sizing: border-box; }
.drawer-search input:focus { border-color: #D97757; }

/* Mobile Responsiveness */
@media (max-width: 768px) {
    body {
        flex-direction: column;
    }
    .sidebar {
        order: 3;
        width: 100%;
        height: 60px;
        flex-direction: row;
        border-right: none;
        border-top: 1px solid var(--glass-border);
        padding: 0 20px;
        z-index: 20;
        /* Padding for iOS safe area if needed */
        padding-bottom: env(safe-area-inset-bottom);
        height: calc(60px + env(safe-area-inset-bottom));
    }
    .sidebar-top, .sidebar-bottom {
        flex-direction: row;
        gap: 16px;
    }
    .main-content {
        order: 1;
        flex: 1;
        width: 100%;
        min-height: 0;
    }
    .history-drawer {
        order: 2;
        width: 100%;
        left: -100%;
        padding-left: 0;
        z-index: 30;
    }
    .top-nav {
        padding: 12px 16px;
    }
    .nav-title {
        display: none;
    }
    .history-drawer.open {
        left: 0;
    }
    .greeting {
        font-size: 26px;
    }
    .asterisk {
        font-size: 28px;
    }
    .input-section {
        padding: 0 16px;
    }
    .chat-container.active-chat {
        padding-top: 60px;
        padding-bottom: 20px;
    }
    .message {
        max-width: 100%;
        padding: 14px;
    }
    .chat-input {
        min-height: 44px;
    }
}