/* ==========================================================================
   OldenWebUI — Design System
   Semantic CSS with custom properties. No build step, no framework.
   ========================================================================== */

/* --------------------------------------------------------------------------
   Theme: Auto (respects OS preference — the default)
   -------------------------------------------------------------------------- */
@media (prefers-color-scheme: dark) {
    :root {
        /* Background palette */
        --bg-root: #0a0a1a;
        --bg-surface: #111128;
        --bg-surface-hover: #181835;
        --bg-sidebar: linear-gradient(90deg, #f8feff 92%, #e4f8fc 100%);
        --bg-input: #141430;
        --bg-bubble-user: rgba(16, 185, 129, 0.08);
        --bg-bubble-assistant: #181835;
        --bg-card: #111128;
        --bg-overlay: rgba(0, 0, 0, 0.65);
        --bg-header-blur: rgba(10, 10, 26, 0.6);

        /* Border colors */
        --border-default: rgba(255, 255, 255, 0.06);
        --border-strong: rgba(255, 255, 255, 0.10);
        --border-accent: rgba(16, 185, 129, 0.35);
        --border-user-bubble: rgba(16, 185, 129, 0.18);
        --border-input: rgba(255, 255, 255, 0.08);
        --border-input-focus: rgba(16, 185, 129, 0.40);

        /* Text colors */
        --text-primary: #e8e8f0;
        --text-secondary: #9d9db8;
        --text-muted: #606080;
        --text-accent: #34d399;
        --text-accent-hover: #6ee7b7;
        --text-danger: #f87171;
        --text-danger-hover: #fca5a5;

        /* Accent colors */
        --accent: #10b981;
        --accent-hover: #059669;
        --accent-soft: rgba(16, 185, 129, 0.12);
        --accent-glow: rgba(16, 185, 129, 0.06);

        /* Overlay / subtle backgrounds */
        --overlay-subtle: rgba(255, 255, 255, 0.03);
        --overlay-hover: rgba(255, 255, 255, 0.04);
        --overlay-active: rgba(255, 255, 255, 0.06);
        --overlay-code: rgba(255, 255, 255, 0.06);

        /* Scrollbar */
        --scrollbar-thumb: rgba(255, 255, 255, 0.08);
        --scrollbar-thumb-hover: rgba(255, 255, 255, 0.14);
        --scrollbar-track: transparent;

        /* Gradient (Gemini-like subtle atmosphere) */
        --chat-gradient: linear-gradient(170deg, #d2f6ff 0%, #f5f5f7 30%, #ffffff 60%, #d2f6ff 100%);

        /* Shadows */
        --shadow-sidebar: 1px 0 0 var(--border-default);
        --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.3);
        --shadow-elevated: 0 4px 24px rgba(0, 0, 0, 0.4);
    }
}

@media (prefers-color-scheme: light) {
    :root {
        /* Background palette */
        --bg-root: #ffffff;
        --bg-surface: #f5f5f7;
        --bg-surface-hover: #e8e8ed;
        --bg-sidebar: #fafafa;
        --bg-input: #ffffff;
        --bg-bubble-user: rgba(16, 185, 129, 0.06);
        --bg-bubble-assistant: #f3f4f6;
        --bg-card: #ffffff;
        --bg-overlay: rgba(0, 0, 0, 0.4);
        --bg-header-blur: rgba(255, 255, 255, 0.75);

        /* Border colors */
        --border-default: rgba(0, 0, 0, 0.08);
        --border-strong: rgba(0, 0, 0, 0.12);
        --border-accent: rgba(16, 185, 129, 0.35);
        --border-user-bubble: rgba(16, 185, 129, 0.15);
        --border-input: rgba(0, 0, 0, 0.12);
        --border-input-focus: rgba(16, 185, 129, 0.45);

        /* Text colors */
        --text-primary: #1a1a2e;
        --text-secondary: #555570;
        --text-muted: #8888a0;
        --text-accent: #059669;
        --text-accent-hover: #047857;
        --text-danger: #dc2626;
        --text-danger-hover: #b91c1c;

        /* Accent colors */
        --accent: #10b981;
        --accent-hover: #059669;
        --accent-soft: rgba(16, 185, 129, 0.08);
        --accent-glow: rgba(16, 185, 129, 0.04);

        /* Overlay / subtle backgrounds */
        --overlay-subtle: rgba(0, 0, 0, 0.02);
        --overlay-hover: rgba(0, 0, 0, 0.04);
        --overlay-active: rgba(0, 0, 0, 0.06);
        --overlay-code: rgba(0, 0, 0, 0.05);

        /* Scrollbar */
        --scrollbar-thumb: rgba(0, 0, 0, 0.12);
        --scrollbar-thumb-hover: rgba(0, 0, 0, 0.20);
        --scrollbar-track: transparent;

        /* Gradient (subtle light atmosphere) */
        --chat-gradient: linear-gradient(
            170deg,
            #fafafa 0%,
            #f5f5f7 30%,
            #ffffff 60%,
            #fafafa 100%
        );

        /* Shadows */
        --shadow-sidebar: 1px 0 0 var(--border-default);
        --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.06);
        --shadow-elevated: 0 4px 24px rgba(0, 0, 0, 0.1);
    }
}

/* --------------------------------------------------------------------------
   Theme: Explicit Dark (overrides auto)
   -------------------------------------------------------------------------- */
[data-theme="dark"] {
    /* Background palette */
    --bg-root: #0a0a1a;
    --bg-surface: #111128;
    --bg-surface-hover: #181835;
    --bg-sidebar: #0d0d24;
    --bg-input: #141430;
    --bg-bubble-user: rgba(16, 185, 129, 0.08);
    --bg-bubble-assistant: #181835;
    --bg-card: #111128;
    --bg-overlay: rgba(0, 0, 0, 0.65);
    --bg-header-blur: rgba(10, 10, 26, 0.6);

    /* Border colors */
    --border-default: rgba(255, 255, 255, 0.06);
    --border-strong: rgba(255, 255, 255, 0.10);
    --border-accent: rgba(16, 185, 129, 0.35);
    --border-user-bubble: rgba(16, 185, 129, 0.18);
    --border-input: rgba(255, 255, 255, 0.08);
    --border-input-focus: rgba(16, 185, 129, 0.40);

    /* Text colors */
    --text-primary: #e8e8f0;
    --text-secondary: #9d9db8;
    --text-muted: #606080;
    --text-accent: #34d399;
    --text-accent-hover: #6ee7b7;
    --text-danger: #f87171;
    --text-danger-hover: #fca5a5;

    /* Accent colors */
    --accent: #10b981;
    --accent-hover: #059669;
    --accent-soft: rgba(16, 185, 129, 0.12);
    --accent-glow: rgba(16, 185, 129, 0.06);

    /* Overlay / subtle backgrounds */
    --overlay-subtle: rgba(255, 255, 255, 0.03);
    --overlay-hover: rgba(255, 255, 255, 0.04);
    --overlay-active: rgba(255, 255, 255, 0.06);
    --overlay-code: rgba(255, 255, 255, 0.06);

    /* Scrollbar */
    --scrollbar-thumb: rgba(255, 255, 255, 0.08);
    --scrollbar-thumb-hover: rgba(255, 255, 255, 0.14);
    --scrollbar-track: transparent;

    /* Gradient */
    --chat-gradient: linear-gradient(
        170deg,
        #0a0a1a 0%,
        #0f0f2a 30%,
        #111128 60%,
        #0d0d24 100%
    );

    /* Shadows */
    --shadow-sidebar: 1px 0 0 var(--border-default);
    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-elevated: 0 4px 24px rgba(0, 0, 0, 0.4);
}

/* --------------------------------------------------------------------------
   Theme: Explicit Light (overrides auto)
   -------------------------------------------------------------------------- */
[data-theme="light"] {
    /* Background palette */
    --bg-root: #ffffff;
    --bg-surface: #f5f5f7;
    --bg-surface-hover: #e8e8ed;
    --bg-sidebar: #fafafa;
    --bg-input: #ffffff;
    --bg-bubble-user: rgba(16, 185, 129, 0.06);
    --bg-bubble-assistant: #f3f4f6;
    --bg-card: #ffffff;
    --bg-overlay: rgba(0, 0, 0, 0.4);
    --bg-header-blur: rgba(255, 255, 255, 0.75);

    /* Border colors */
    --border-default: rgba(0, 0, 0, 0.08);
    --border-strong: rgba(0, 0, 0, 0.12);
    --border-accent: rgba(16, 185, 129, 0.35);
    --border-user-bubble: rgba(16, 185, 129, 0.15);
    --border-input: rgba(0, 0, 0, 0.12);
    --border-input-focus: rgba(16, 185, 129, 0.45);

    /* Text colors */
    --text-primary: #1a1a2e;
    --text-secondary: #555570;
    --text-muted: #8888a0;
    --text-accent: #059669;
    --text-accent-hover: #047857;
    --text-danger: #dc2626;
    --text-danger-hover: #b91c1c;

    /* Accent colors */
    --accent: #10b981;
    --accent-hover: #059669;
    --accent-soft: rgba(16, 185, 129, 0.08);
    --accent-glow: rgba(16, 185, 129, 0.04);

    /* Overlay / subtle backgrounds */
    --overlay-subtle: rgba(0, 0, 0, 0.02);
    --overlay-hover: rgba(0, 0, 0, 0.04);
    --overlay-active: rgba(0, 0, 0, 0.06);
    --overlay-code: rgba(0, 0, 0, 0.05);

    /* Scrollbar */
    --scrollbar-thumb: rgba(0, 0, 0, 0.12);
    --scrollbar-thumb-hover: rgba(0, 0, 0, 0.20);
    --scrollbar-track: transparent;

    /* Gradient */
    --chat-gradient: linear-gradient(
        170deg,
        #fafafa 0%,
        #f5f5f7 30%,
        #ffffff 60%,
        #fafafa 100%
    );

    /* Shadows */
    --shadow-sidebar: 1px 0 0 var(--border-default);
    --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.06);
    --shadow-elevated: 0 4px 24px rgba(0, 0, 0, 0.1);
}

/* --------------------------------------------------------------------------
   Shared Tokens (same across all themes)
   -------------------------------------------------------------------------- */
:root {
    /* Spacing scale */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 0.75rem;
    --space-lg: 1rem;
    --space-xl: 1.5rem;
    --space-2xl: 2rem;
    --space-3xl: 3rem;

    /* Border radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-xl: 18px;
    --radius-full: 9999px;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'Fira Mono', 'Roboto Mono', monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.8125rem;
    --font-size-base: 0.875rem;
    --font-size-md: 0.9375rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;

    /* Chat max-width (Gemini-like readability) */
    --chat-max-width: 48rem;

    /* Sidebar width */
    --sidebar-width: 18rem;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 200ms ease;
    --transition-slow: 300ms ease;
}

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

html {
    height: 100%;
    font-family: var(--font-sans);
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    height: 100%;
    background: var(--bg-root);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
}

a {
    color: var(--text-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}
a:hover { color: var(--text-accent-hover); }

/* Scrollbar (FEAT-018 / FEAT-019 theme-aware) */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--scrollbar-track); }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: var(--radius-full); }
::-webkit-scrollbar-thumb:hover { background: var(--scrollbar-thumb-hover); }
* { scrollbar-width: thin; scrollbar-color: var(--scrollbar-thumb) var(--scrollbar-track); }

/* ==========================================================================
   Layout
   ========================================================================== */
.app-layout { display: flex; height: 100%; position: relative; }

/* Sidebar */
.sidebar {
    position: fixed; inset: 0; z-index: 50;
    width: var(--sidebar-width);
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-default);
    display: flex; flex-direction: column; flex-shrink: 0;
    transform: translateX(-100%);
    transition: transform var(--transition-slow);
}
.sidebar.open { transform: translateX(0); }

.sidebar-backdrop {
    position: fixed; inset: 0; z-index: 40;
    background: var(--bg-overlay);
    opacity: 0; pointer-events: none;
    transition: opacity var(--transition-slow);
}
.sidebar-backdrop.visible { opacity: 1; pointer-events: auto; }

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

.sidebar-brand {
    font-size: var(--font-size-lg); font-weight: 700;
    background: linear-gradient(135deg, var(--text-accent), #22d3ee);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent;
    background-clip: text;
}

.sidebar-header-links { display: flex; align-items: center; gap: var(--space-md); }
.sidebar-header-links a { font-size: var(--font-size-sm); color: var(--text-muted); }
.sidebar-header-links a:hover { color: var(--text-secondary); }
.sidebar-header-links .logout-link:hover { color: var(--text-danger); }

/* Sidebar search (FEAT-020) */
.sidebar-search { padding: var(--space-sm) var(--space-md); padding-bottom: 0; }
.search-wrapper { position: relative; }
.search-input {
    width: 100%; background: var(--bg-input); border: 1px solid var(--border-input);
    border-radius: var(--radius-md); padding: 0.5rem 2rem 0.5rem 2.25rem;
    font-size: var(--font-size-sm); color: var(--text-primary); outline: none;
    transition: border-color var(--transition-fast);
}
.search-input::placeholder { color: var(--text-muted); }
.search-input:focus { border-color: var(--border-input-focus); }
.search-icon {
    position: absolute; left: 0.7rem; top: 50%; transform: translateY(-50%);
    width: 1rem; height: 1rem; color: var(--text-muted); pointer-events: none;
}
.search-clear {
    position: absolute; right: 0.4rem; top: 50%; transform: translateY(-50%);
    background: none; border: none; color: var(--text-muted); cursor: pointer;
    padding: 0.2rem; border-radius: var(--radius-sm); display: none;
    align-items: center; justify-content: center;
}
.search-clear.visible { display: flex; }
.search-clear:hover { color: var(--text-secondary); }
.search-spinner { position: absolute; right: 1.8rem; top: 50%; transform: translateY(-50%); display: none; }
.search-spinner.active { display: block; }
.search-spinner-icon {
    width: 1rem; height: 1rem; color: var(--text-accent);
    animation: spin 0.8s linear infinite;
}

/* Sidebar new chat */
.sidebar-new-chat { padding: var(--space-md); }
.btn-new-chat {
    width: 100%; text-align: left; background: var(--bg-input);
    color: var(--text-secondary); border: 1px solid var(--border-strong);
    border-radius: var(--radius-md); padding: 0.625rem var(--space-lg);
    font-size: var(--font-size-sm); cursor: pointer;
    transition: background var(--transition-fast), color var(--transition-fast);
}
.btn-new-chat:hover { background: var(--bg-surface-hover); color: var(--text-primary); }

/* Chat list */
.chat-list { flex: 1; overflow-y: auto; padding: 0 var(--space-md) var(--space-md); }
.chat-list-empty { color: var(--text-muted); font-size: var(--font-size-sm); text-align: center; padding: var(--space-2xl) var(--space-lg); line-height: 1.6; }
.chat-list-item { display: flex; align-items: center; gap: 2px; }
.chat-list-link {
    flex: 1; display: block; padding: 0.625rem var(--space-md);
    border-radius: var(--radius-md); font-size: var(--font-size-sm);
    color: var(--text-muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
    transition: background var(--transition-fast), color var(--transition-fast);
}
.chat-list-link:hover { background: var(--overlay-hover); color: var(--text-secondary); }
.chat-list-link.active { background: var(--overlay-active); color: var(--text-primary); }
.chat-list-delete {
    display: none; background: none; border: none; color: var(--text-muted);
    cursor: pointer; padding: 0.25rem; border-radius: var(--radius-sm); flex-shrink: 0;
    transition: color var(--transition-fast);
}
.chat-list-item:hover .chat-list-delete { display: block; }
.chat-list-delete:hover { color: var(--text-danger); }
.chat-list-delete-icon { width: 0.875rem; height: 0.875rem; }

/* Sidebar footer */
.sidebar-footer { padding: var(--space-md); border-top: 1px solid var(--border-default); }
.btn-delete-all {
    width: 100%; text-align: left; background: none; border: none;
    color: rgba(248,113,113,0.45); font-size: var(--font-size-xs); cursor: pointer;
    padding: var(--space-sm) var(--space-md); border-radius: var(--radius-md);
    transition: color var(--transition-fast), background var(--transition-fast);
}
.btn-delete-all:hover { color: var(--text-danger); background: rgba(248,113,113,0.08); }

/* ==========================================================================
   Main Chat Area
   ========================================================================== */
.main-area {
    flex: 1; display: flex; flex-direction: column; min-width: 0; width: 100%;
    background: var(--chat-gradient);
}

/* Chat header */
.chat-header {
    padding: var(--space-md) var(--space-xl);
    border-bottom: 1px solid var(--border-default);
    display: flex; align-items: center; gap: var(--space-md); flex-shrink: 0;
    backdrop-filter: blur(8px); background: var(--bg-header-blur);
}
.chat-header-title {
    font-size: var(--font-size-sm); font-weight: 500; color: var(--text-secondary);
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.chat-header-spacer { flex: 1; }
.chat-header-select {
    background: var(--bg-input); border: 1px solid var(--border-input);
    border-radius: var(--radius-md); padding: 0.375rem 0.75rem;
    font-size: var(--font-size-sm); color: var(--text-primary); outline: none; cursor: pointer;
    transition: border-color var(--transition-fast);
}
.chat-header-select:focus { border-color: var(--border-input-focus); }
.chat-header-select option { background: var(--bg-surface); color: var(--text-primary); }

.btn-hamburger {
    display: none; background: none; border: none; color: var(--text-muted);
    cursor: pointer; padding: 0.25rem; border-radius: var(--radius-sm); flex-shrink: 0;
}
.btn-hamburger:hover { color: var(--text-secondary); }
.btn-hamburger-icon { width: 1.5rem; height: 1.5rem; }

/* Chat content */
.chat-scroll { flex: 1; overflow-y: auto; display: flex; flex-direction: column; }
.chat-wrapper { flex: 1; display: flex; flex-direction: column; }
.chat-centered {
    width: 100%; max-width: var(--chat-max-width); margin: 0 auto;
    flex: 1; display: flex; flex-direction: column;
}

/* Empty state */
.chat-empty {
    flex: 1; display: flex; flex-direction: column; align-items: center;
    justify-content: center; padding: var(--space-3xl) var(--space-xl); text-align: center;
}
.chat-empty-greeting { font-size: var(--font-size-2xl); font-weight: 700; color: var(--text-primary); margin-bottom: var(--space-sm); }
.chat-empty-subtitle { font-size: var(--font-size-base); color: var(--text-muted); margin-bottom: var(--space-2xl); max-width: 28rem; line-height: 1.7; }

/* Messages */
.messages-area { padding: var(--space-xl) var(--space-xl) 0; flex: 1; }
.messages-list { display: flex; flex-direction: column; gap: var(--space-lg); }

/* Message bubbles */
.message-row { display: flex; }
.message-row.user { justify-content: flex-end; }
.message-row.assistant { justify-content: flex-start; }
.message-bubble {
    position: relative; max-width: 85%; border-radius: var(--radius-xl);
    padding: var(--space-md) var(--space-lg); font-size: var(--font-size-md); line-height: 1.65;
}
.message-bubble.user {
    background: var(--bg-bubble-user); border: 1px solid var(--border-user-bubble);
    color: var(--text-primary); border-bottom-right-radius: var(--radius-sm);
}
.message-bubble.assistant {
    background: var(--bg-bubble-assistant); border: 1px solid var(--border-default);
    color: var(--text-primary); border-bottom-left-radius: var(--radius-sm);
}
.message-label { font-size: var(--font-size-xs); color: var(--text-muted); margin-bottom: 0.25rem; }
.message-content { color: var(--text-primary); }
.message-content-plain { white-space: pre-wrap; word-break: break-word; }
.message-edit {
    position: absolute; top: 0.5rem; right: 1.75rem; display: none;
    background: none; border: none; color: var(--text-muted); cursor: pointer;
    padding: 0.25rem; border-radius: var(--radius-sm);
    transition: color var(--transition-fast);
}
.message-row:hover .message-edit { display: block; }
.message-edit:hover { color: var(--text-accent); }
.message-edit-icon { width: 0.75rem; height: 0.75rem; }

.message-delete {
    position: absolute; top: 0.5rem; right: 0.5rem; display: none;
    background: none; border: none; color: var(--text-muted); cursor: pointer;
    padding: 0.25rem; border-radius: var(--radius-sm);
    transition: color var(--transition-fast);
}
.message-row:hover .message-delete { display: block; }
.message-delete:hover { color: var(--text-danger); }
.message-delete-icon { width: 0.75rem; height: 0.75rem; }

/* Inline message edit form */
.message-edit-form {
    margin-top: var(--space-md);
}
.message-edit-textarea {
    width: 100%; min-height: 5rem;
    background: var(--bg-input); border: 1px solid var(--border-input-focus);
    border-radius: var(--radius-md); padding: 0.625rem var(--space-md);
    font-size: var(--font-size-sm); font-family: var(--font-sans);
    color: var(--text-primary); outline: none; resize: vertical;
    line-height: 1.6;
}
.message-edit-textarea:focus { border-color: var(--accent); }
.message-edit-actions {
    display: flex; gap: var(--space-sm); margin-top: var(--space-sm);
    justify-content: flex-end;
}
.message-edit-save {
    background: var(--accent); color: #fff; border: none;
    border-radius: var(--radius-md); padding: 0.375rem var(--space-lg);
    font-size: var(--font-size-sm); cursor: pointer;
    transition: background var(--transition-fast);
}
.message-edit-save:hover { background: var(--accent-hover); }
.message-edit-cancel {
    background: none; border: 1px solid var(--border-strong);
    color: var(--text-secondary); border-radius: var(--radius-md);
    padding: 0.375rem var(--space-lg); font-size: var(--font-size-sm);
    cursor: pointer; transition: background var(--transition-fast), color var(--transition-fast);
}
.message-edit-cancel:hover { background: var(--overlay-hover); color: var(--text-primary); }

/* Error message bubble */
.message-bubble.error {
    background: rgba(248,113,113,0.1); border: 1px solid rgba(248,113,113,0.25);
    border-bottom-left-radius: var(--radius-sm);
}
.message-bubble.error:hover .message-delete { display: block; }

/* Generated image in chat */
.message-image {
    margin-top: var(--space-md); border-radius: var(--radius-md);
    overflow: hidden; border: 1px solid var(--border-default);
}
.message-image-img { width: 100%; max-width: 24rem; display: block; }
.message-image-caption { padding: 0.5rem var(--space-md); background: var(--overlay-subtle); }
.message-image-prompt { font-size: var(--font-size-xs); color: var(--text-muted); }

/* Loading indicator */
.loading-indicator { display: none; padding: 0 var(--space-xl); max-width: var(--chat-max-width); margin: 0 auto; width: 100%; }
.loading-indicator.visible { display: block; }
.loading-bubble {
    display: inline-flex; align-items: center; gap: var(--space-sm);
    max-width: 85%; border-radius: var(--radius-xl); border-bottom-left-radius: var(--radius-sm);
    padding: var(--space-md) var(--space-lg);
    background: var(--bg-bubble-assistant); border: 1px solid var(--border-default);
}
.loading-dot {
    width: 0.4rem; height: 0.4rem; background: var(--text-accent);
    border-radius: var(--radius-full); animation: bounce 1.2s infinite ease-in-out;
}
.loading-dot:nth-child(1) { animation-delay: 0ms; }
.loading-dot:nth-child(2) { animation-delay: 150ms; }
.loading-dot:nth-child(3) { animation-delay: 300ms; }
.loading-text { font-size: var(--font-size-sm); color: var(--text-muted); }

/* Chat input */
.chat-input-area { padding: var(--space-lg) var(--space-xl) var(--space-xl); max-width: var(--chat-max-width); margin: 0 auto; width: 100%; }
.chat-input-area.centered { max-width: 42rem; }
.chat-input-form { display: flex; gap: var(--space-md); }
.chat-input-textarea {
    flex: 1; background: var(--bg-input); border: 1px solid var(--border-input);
    border-radius: var(--radius-lg); padding: 0.75rem var(--space-lg);
    font-size: var(--font-size-sm); font-family: var(--font-sans); color: var(--text-primary);
    outline: none; resize: none; line-height: 1.6;
    transition: border-color var(--transition-fast);
    min-height: 2.75rem; max-height: 50vh;
}
.chat-input-textarea::placeholder { color: var(--text-muted); }
.chat-input-textarea:focus { border-color: var(--border-input-focus); }
.btn-send {
    background: var(--accent); color: #fff; border: none; border-radius: var(--radius-lg);
    padding: 0 var(--space-xl); cursor: pointer; flex-shrink: 0;
    transition: background var(--transition-fast);
    display: flex; align-items: center; justify-content: center;
}
.btn-send:hover { background: var(--accent-hover); }
.btn-send-icon { width: 1.125rem; height: 1.125rem; }

/* Image gen bar */
.image-gen-bar { margin-top: var(--space-md); display: flex; align-items: center; gap: var(--space-sm); font-size: var(--font-size-xs); }
.image-gen-bar a, .image-gen-bar button { background: none; border: none; color: var(--text-muted); font-size: var(--font-size-xs); cursor: pointer; padding: 0; transition: color var(--transition-fast); }
.image-gen-bar a:hover, .image-gen-bar button:hover { color: var(--text-secondary); }
.image-gen-bar .image-gen-trigger { color: #a78bfa; }
.image-gen-bar .image-gen-trigger:hover { color: #c4b5fd; }
.image-gen-separator { color: var(--border-strong); }
.image-gen-form-container { margin-top: var(--space-md); display: none; }
.image-gen-form-container.visible { display: block; }
.image-gen-form { display: flex; gap: var(--space-md); }
.image-gen-input {
    flex: 1; background: var(--bg-input); border: 1px solid rgba(167,139,250,0.25);
    border-radius: var(--radius-md); padding: 0.625rem var(--space-md);
    font-size: var(--font-size-sm); color: var(--text-primary); outline: none;
}
.image-gen-input::placeholder { color: var(--text-muted); }
.image-gen-input:focus { border-color: rgba(167,139,250,0.45); }
.image-gen-select {
    background: var(--bg-input); border: 1px solid rgba(167,139,250,0.25);
    border-radius: var(--radius-md); padding: 0.625rem var(--space-md);
    font-size: var(--font-size-sm); color: var(--text-secondary); outline: none; cursor: pointer;
}
.btn-generate-image {
    background: #7c3aed; color: #fff; border: none; border-radius: var(--radius-md);
    padding: 0.625rem var(--space-lg); font-size: var(--font-size-sm); cursor: pointer; flex-shrink: 0;
    transition: background var(--transition-fast);
}
.btn-generate-image:hover { background: #6d28d9; }
.btn-cancel-image { background: none; border: none; color: var(--text-muted); font-size: var(--font-size-sm); cursor: pointer; padding: 0 var(--space-sm); }
.btn-cancel-image:hover { color: var(--text-secondary); }

/* Landing page */
.landing { flex: 1; display: flex; align-items: center; justify-content: center; }
.landing-content { text-align: center; }
.landing-title { font-size: var(--font-size-2xl); font-weight: 700; color: var(--text-secondary); margin-bottom: var(--space-sm); }
.landing-subtitle { color: var(--text-muted); margin-bottom: var(--space-xl); font-size: var(--font-size-base); }
.btn-start-chat {
    display: inline-block; background: var(--accent); color: #fff; font-weight: 500;
    border: none; border-radius: var(--radius-md); padding: 0.75rem var(--space-2xl);
    font-size: var(--font-size-sm); cursor: pointer;
    transition: background var(--transition-fast);
}
.btn-start-chat:hover { background: var(--accent-hover); }

/* Image modal */
.image-modal {
    position: fixed; inset: 0; z-index: 60; background: rgba(0,0,0,0.92);
    display: none; align-items: center; justify-content: center; cursor: pointer;
}
.image-modal.visible { display: flex; }
.image-modal-img { max-width: 95vw; max-height: 95vh; object-fit: contain; border-radius: var(--radius-md); }
.image-modal-close { position: absolute; top: var(--space-lg); right: var(--space-lg); background: none; border: none; color: rgba(255,255,255,0.6); font-size: 2rem; cursor: pointer; line-height: 1; padding: var(--space-sm); }
.image-modal-close:hover { color: #fff; }

/* ==========================================================================
   Markdown Content
   ========================================================================== */
.markdown-content p { margin-bottom: 0.5rem; }
.markdown-content p:last-child { margin-bottom: 0; }
.markdown-content code { background: var(--overlay-code); padding: 0.125rem 0.375rem; border-radius: 4px; font-size: 0.85em; font-family: var(--font-mono); }
.markdown-content pre { background: #0a0a1a; padding: var(--space-lg); border-radius: var(--radius-md); overflow-x: auto; margin: 0.75rem 0; border: 1px solid var(--border-default); }
.markdown-content pre code { background: none; padding: 0; }
.markdown-content ul, .markdown-content ol { padding-left: 1.5rem; margin-bottom: 0.5rem; }
.markdown-content table { width: 100%; border-collapse: collapse; margin: 0.75rem 0; }
.markdown-content th, .markdown-content td { border: 1px solid var(--border-default); padding: 0.5rem; text-align: left; }
.markdown-content th { background: var(--overlay-subtle); }
.markdown-content blockquote { border-left: 3px solid var(--accent); padding-left: var(--space-lg); color: var(--text-secondary); margin: 0.75rem 0; }
.markdown-content h1, .markdown-content h2, .markdown-content h3, .markdown-content h4 { font-weight: 600; margin: 1rem 0 0.5rem; color: var(--text-primary); }
.markdown-content h1 { font-size: 1.4em; }
.markdown-content h2 { font-size: 1.2em; }
.markdown-content h3 { font-size: 1.05em; }
.markdown-content a { color: var(--text-accent); text-decoration: underline; }
.markdown-content hr { border: none; border-top: 1px solid var(--border-default); margin: 1rem 0; }
.markdown-content img { cursor: pointer; border-radius: var(--radius-sm); max-width: 100%; transition: opacity var(--transition-fast); }
.markdown-content img:hover { opacity: 0.85; }
.copy-code-btn {
    position: absolute; top: 0.5rem; right: 0.5rem;
    background: var(--overlay-code); border: none; color: var(--text-muted);
    border-radius: var(--radius-sm); padding: 0.25rem 0.5rem;
    font-size: var(--font-size-xs); cursor: pointer; opacity: 0;
    transition: opacity var(--transition-fast), background var(--transition-fast), color var(--transition-fast);
}
.markdown-content pre:hover .copy-code-btn,
.markdown-content pre .copy-code-btn:hover { opacity: 1; }
.copy-code-btn:hover { background: var(--overlay-active); color: var(--text-primary); }

/* ==========================================================================
   Settings Page
   ========================================================================== */
.settings-page { height: 100%; overflow-y: auto; padding: var(--space-2xl); }
.settings-container { max-width: 56rem; margin: 0 auto; }
.settings-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: var(--space-2xl); }
.settings-title { font-size: var(--font-size-xl); font-weight: 700; color: var(--text-primary); }
.settings-subtitle { color: var(--text-muted); margin-top: 0.25rem; font-size: var(--font-size-sm); }
.settings-back-link { font-size: var(--font-size-sm); color: var(--text-accent); }

.card {
    background: var(--bg-card); border: 1px solid var(--border-default);
    border-radius: var(--radius-lg); overflow: hidden; margin-bottom: var(--space-2xl);
}
.card-header { padding: var(--space-lg) var(--space-xl); border-bottom: 1px solid var(--border-default); display: flex; align-items: center; justify-content: space-between; }
.card-title { font-size: var(--font-size-md); font-weight: 600; color: var(--text-primary); }
.card-body { padding: var(--space-xl); }
.card-footer { padding: var(--space-lg) var(--space-xl); border-top: 1px solid var(--border-default); }

/* Forms */
.form-group { margin-bottom: var(--space-lg); }
.form-label { display: block; font-size: var(--font-size-sm); font-weight: 500; color: var(--text-secondary); margin-bottom: 0.375rem; }
.form-input, .form-select, .form-textarea {
    width: 100%; background: var(--bg-input); border: 1px solid var(--border-input);
    border-radius: var(--radius-md); padding: 0.625rem var(--space-md);
    font-size: var(--font-size-sm); color: var(--text-primary); font-family: var(--font-sans); outline: none;
    transition: border-color var(--transition-fast);
}
.form-input::placeholder, .form-textarea::placeholder { color: var(--text-muted); }
.form-input:focus, .form-select:focus, .form-textarea:focus { border-color: var(--border-input-focus); }
.form-textarea { resize: vertical; min-height: 5rem; }
.form-select { cursor: pointer; }
.form-select option { background: var(--bg-surface); color: var(--text-primary); }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-lg); }
.form-check { display: flex; align-items: center; gap: var(--space-sm); cursor: pointer; }
.form-check input[type="checkbox"] { width: 1rem; height: 1rem; accent-color: var(--accent); border-radius: 4px; cursor: pointer; }
.form-check-label { font-size: var(--font-size-sm); color: var(--text-secondary); }

/* Buttons */
.btn {
    display: inline-flex; align-items: center; gap: var(--space-sm);
    font-size: var(--font-size-sm); font-weight: 500; border: none;
    border-radius: var(--radius-md); padding: 0.625rem var(--space-lg); cursor: pointer;
    transition: background var(--transition-fast), color var(--transition-fast);
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: var(--bg-input); color: var(--text-secondary); border: 1px solid var(--border-strong); }
.btn-secondary:hover { background: var(--bg-surface-hover); color: var(--text-primary); }
.btn-purple { background: #7c3aed; color: #fff; }
.btn-purple:hover { background: #6d28d9; }
.btn-sm { padding: 0.375rem 0.75rem; font-size: var(--font-size-xs); }
.btn-xs { padding: 0.25rem 0.5rem; font-size: var(--font-size-xs); }
.btn-danger-text { background: none; color: var(--text-danger); padding: 0.25rem 0.5rem; font-size: var(--font-size-xs); }
.btn-danger-text:hover { color: var(--text-danger-hover); }

/* Theme selector (FEAT-019) */
.theme-selector { display: flex; gap: var(--space-sm); }
.theme-option {
    flex: 1; background: var(--bg-input); border: 2px solid var(--border-input);
    border-radius: var(--radius-md); padding: var(--space-md);
    font-size: var(--font-size-sm); color: var(--text-secondary); cursor: pointer;
    text-align: center; transition: border-color var(--transition-fast), background var(--transition-fast), color var(--transition-fast);
}
.theme-option:hover { border-color: var(--border-input-focus); color: var(--text-primary); }
.theme-option.selected { border-color: var(--accent); color: var(--text-accent); background: var(--accent-soft); }
.theme-option-icon { display: block; font-size: 1.25rem; margin-bottom: 0.25rem; }

/* Provider list */
.provider-item {
    display: flex; align-items: center; justify-content: space-between;
    padding: var(--space-lg) var(--space-xl); border-bottom: 1px solid var(--border-default);
    transition: background var(--transition-fast);
}
.provider-item:last-child { border-bottom: none; }
.provider-item:hover { background: var(--overlay-subtle); }
.provider-info { display: flex; align-items: center; gap: var(--space-lg); }
.provider-status { width: 0.5rem; height: 0.5rem; border-radius: var(--radius-full); }
.provider-status.active { background: var(--accent); }
.provider-status.inactive { background: var(--text-muted); }
.provider-name { font-weight: 500; color: var(--text-primary); font-size: var(--font-size-sm); }
.provider-type-tag { font-size: var(--font-size-xs); color: var(--text-muted); background: var(--bg-input); border-radius: var(--radius-sm); padding: 0.125rem 0.5rem; }
.provider-actions { display: flex; align-items: center; gap: var(--space-sm); }

/* System prompts */
.system-prompt-item { background: var(--bg-input); border: 1px solid var(--border-default); border-radius: var(--radius-md); padding: var(--space-lg); margin-bottom: var(--space-md); }
.system-prompt-item.default { box-shadow: 0 0 0 1px rgba(16,185,129,0.3); }
.system-prompt-header { display: flex; align-items: flex-start; justify-content: space-between; gap: var(--space-lg); }
.system-prompt-info { flex: 1; min-width: 0; }
.system-prompt-name-row { display: flex; align-items: center; gap: var(--space-sm); margin-bottom: 0.25rem; }
.system-prompt-name { font-size: var(--font-size-sm); font-weight: 500; color: var(--text-primary); }
.system-prompt-badge { font-size: var(--font-size-xs); background: rgba(16,185,129,0.12); color: var(--text-accent); border-radius: var(--radius-full); padding: 0.125rem 0.5rem; }
.system-prompt-temp { font-size: var(--font-size-xs); color: var(--text-muted); }
.system-prompt-text { font-size: var(--font-size-xs); color: var(--text-muted); display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.system-prompt-actions { display: flex; align-items: center; gap: 0.25rem; flex-shrink: 0; }

/* Alerts */
.alert { border-radius: var(--radius-md); padding: var(--space-md) var(--space-lg); font-size: var(--font-size-sm); margin-bottom: var(--space-lg); }
.alert-error { background: rgba(248,113,113,0.1); border: 1px solid rgba(248,113,113,0.25); color: #fca5a5; }
.alert-success { background: rgba(16,185,129,0.1); border: 1px solid rgba(16,185,129,0.25); color: var(--text-accent); }

/* Import/Export */
.import-export-actions { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-lg); }
.import-status { display: none; margin-top: var(--space-md); font-size: var(--font-size-sm); }
.import-status.visible { display: block; }

/* ==========================================================================
   Image Gallery
   ========================================================================== */
.gallery-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-lg);
}
.gallery-card {
    background: var(--bg-card);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-lg);
    overflow: hidden;
    position: relative;
}
.gallery-card:hover .gallery-delete { display: block; }
.gallery-delete {
    display: none;
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    z-index: 10;
    background: rgba(220,38,38,0.8);
    border: none;
    color: #fff;
    border-radius: var(--radius-md);
    padding: 0.25rem 0.5rem;
    font-size: var(--font-size-xs);
    cursor: pointer;
    transition: background var(--transition-fast);
}
.gallery-delete:hover { background: rgb(220,38,38); }
.gallery-img {
    width: 100%;
    height: 12rem;
    object-fit: cover;
    cursor: pointer;
    transition: opacity var(--transition-fast);
}
.gallery-img:hover { opacity: 0.85; }
.gallery-card-body { padding: var(--space-md); }
.gallery-prompt {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.gallery-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: var(--space-sm);
    font-size: var(--font-size-xs);
    color: var(--text-muted);
}
.gallery-pagination {
    display: flex;
    justify-content: center;
    gap: var(--space-sm);
    margin-top: var(--space-2xl);
}
.gallery-page {
    background: var(--bg-input);
    color: var(--text-muted);
    border-radius: var(--radius-md);
    padding: 0.375rem 0.75rem;
    font-size: var(--font-size-sm);
    transition: background var(--transition-fast), color var(--transition-fast);
}
.gallery-page:hover { background: var(--bg-surface-hover); color: var(--text-secondary); }
.gallery-page-active {
    background: var(--accent);
    color: #fff;
    border-radius: var(--radius-md);
    padding: 0.375rem 0.75rem;
    font-size: var(--font-size-sm);
}

@media (min-width: 768px) { .gallery-grid { grid-template-columns: repeat(3, 1fr); } }
@media (min-width: 1024px) { .gallery-grid { grid-template-columns: repeat(4, 1fr); } }

/* ==========================================================================
   Login / Setup Pages
   ========================================================================== */
.auth-page { min-height: 100%; min-width: 100%; display: flex; align-items: center; justify-content: center; padding: var(--space-2xl); background: var(--chat-gradient); }
.auth-card { width: 100%; max-width: 26rem; background: var(--bg-card); border: 1px solid var(--border-default); border-radius: var(--radius-lg); padding: var(--space-2xl); }
.auth-title { font-size: var(--font-size-xl); font-weight: 700; color: var(--text-primary); margin-bottom: var(--space-sm); text-align: center; }
.auth-subtitle { font-size: var(--font-size-sm); color: var(--text-muted); text-align: center; margin-bottom: var(--space-xl); }

/* ==========================================================================
   Utilities
   ========================================================================== */
.hidden { display: none !important; }
.flex-1 { flex: 1; }
.text-center { text-align: center; }
.truncate { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }
.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mt-2xl { margin-top: var(--space-2xl); }
.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }
.htmx-indicator { display: none; }
.htmx-request .htmx-indicator,
.htmx-request.htmx-indicator { display: inline-flex; }

/* ==========================================================================
   Animations
   ========================================================================== */
@keyframes bounce {
    0%, 80%, 100% { transform: scale(0.6); opacity: 0.4; }
    40% { transform: scale(1); opacity: 1; }
}
@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* ==========================================================================
   Advanced Parameters (frequency_penalty / presence_penalty)
   ========================================================================== */
.advanced-toggle {
    background: var(--bg-input);
    border: 1px solid var(--border-input);
    border-radius: var(--radius-md);
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.375rem 0.625rem;
    font-size: var(--font-size-sm);
    line-height: 1;
    transition: color var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast);
}
.advanced-toggle:hover { color: var(--text-secondary); border-color: var(--border-strong); }
.advanced-toggle.active { color: var(--text-accent); border-color: var(--border-accent); background: var(--accent-soft); }

.advanced-panel {
    padding: var(--space-sm) var(--space-xl);
    border-bottom: 1px solid var(--border-default);
    background: var(--bg-surface);
}
.advanced-panel-inner {
    display: flex;
    gap: var(--space-lg);
    align-items: flex-end;
}
.penalty-input-group {
    display: flex;
    flex-direction: column;
    gap: 2px;
}
.penalty-label {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    font-weight: 500;
}
.penalty-input {
    width: 5.5rem;
    background: var(--bg-input);
    border: 1px solid var(--border-input);
    border-radius: var(--radius-sm);
    padding: 0.3rem 0.5rem;
    font-size: var(--font-size-sm);
    color: var(--text-primary);
    outline: none;
    transition: border-color var(--transition-fast);
    -moz-appearance: textfield;
}
.penalty-input::-webkit-inner-spin-button,
.penalty-input::-webkit-outer-spin-button { opacity: 1; }
.penalty-input:focus { border-color: var(--border-input-focus); }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (min-width: 768px) {
    .sidebar { position: relative; transform: translateX(0); }
    .sidebar-backdrop { display: none; }
    .btn-hamburger { display: none; }
}
@media (max-width: 767px) {
    .sidebar { transform: translateX(-100%); }
    .sidebar.open { transform: translateX(0); }
    .btn-hamburger { display: block; }
    .chat-header { padding: var(--space-md); }
    .chat-centered { max-width: 100%; }
    .messages-area { padding: var(--space-lg) var(--space-md) 0; }
    .chat-input-area { padding: var(--space-md) var(--space-md) var(--space-lg); }
    .loading-indicator { padding: 0 var(--space-md); }
    .form-row { grid-template-columns: 1fr; }
    .settings-page { padding: var(--space-lg); }
    .provider-item { flex-direction: column; align-items: flex-start; gap: var(--space-md); }
}