:root {
    --bg: #f8f9fa;
    --bg-card: #ffffff;
    --bg-input: #f0f1f3;
    --text: #333333;
    --text-muted: #888888;
    --accent: #5b7ff6;
    --accent-hover: #4a6de8;
    --user-bubble: #eef2ff;
    --assistant-bubble: #f8f9fb;
    --border: #e5e7eb;
    --success: #4ade80;
    --error: #f44336;
    --error-bg: #fde8e8;
    --radius: 6px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    height: 100vh;
    overflow: hidden;
}

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

.sidebar {
    width: 280px;
    min-width: 280px;
    background: var(--bg-card);
    border-right: 1px solid var(--border);
    box-shadow: 1px 0 4px rgba(0, 0, 0, 0.04);
    display: flex;
    flex-direction: column;
    padding: 16px;
}

.sidebar-header {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 0 16px;
}

.sidebar-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--accent);
}

.btn-new {
    width: 100%;
    padding: 10px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.95rem;
    margin-bottom: 12px;
    transition: background 0.2s;
}
.btn-new:hover { background: var(--accent-hover); }

.conversation-list {
    flex: 1;
    overflow-y: auto;
    margin-bottom: 12px;
}

.conversation-item {
    padding: 10px 12px;
    border-radius: var(--radius);
    cursor: pointer;
    margin-bottom: 4px;
    transition: background 0.15s;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.9rem;
}
.conversation-item:hover { background: var(--bg-input); }
.conversation-item.active { background: var(--bg-input); border-left: 3px solid var(--accent); box-shadow: 0 0 4px rgba(91, 127, 246, 0.15); }
.conversation-item .title { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: 1; }
.conversation-item .delete-convo {
    opacity: 0;
    background: none;
    border: none;
    color: var(--error);
    cursor: pointer;
    font-size: 1rem;
    transition: opacity 0.15s;
}
.conversation-item:hover .delete-convo { opacity: 1; }

.no-conversations {
    color: var(--text-muted);
    text-align: center;
    padding: 20px 0;
    font-size: 0.85rem;
}

.btn-settings {
    padding: 10px;
    background: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.9rem;
    transition: background 0.15s;
}
.btn-settings:hover { background: var(--border); }

.chat-area {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.chat-header {
    padding: 12px 20px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    background: var(--bg-card);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

#model-selector {
    padding: 8px 12px;
    background: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 0.9rem;
    min-width: 250px;
    cursor: pointer;
}

.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.message {
    max-width: 80%;
    padding: 12px 16px;
    border-radius: var(--radius);
    line-height: 1.6;
    font-size: 0.95rem;
    white-space: pre-wrap;
    word-wrap: break-word;
}
.message.user {
    align-self: flex-end;
    background: var(--user-bubble);
    border: 1px solid #d5dbf0;
}
.message.assistant {
    align-self: flex-start;
    background: var(--assistant-bubble);
    border: 1px solid var(--border);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.message img {
    max-width: 100%;
    max-height: 300px;
    border-radius: 4px;
    margin-top: 8px;
    cursor: pointer;
    transition: opacity 0.15s;
}
.message img:hover { opacity: 0.85; }

.cursor {
    display: inline-block;
    width: 8px;
    height: 18px;
    background: var(--accent);
    animation: blink 0.8s infinite;
    vertical-align: text-bottom;
    margin-left: 2px;
}

@keyframes blink {
    0%, 100% { opacity: 1; }
    50% { opacity: 0; }
}

.error-message {
    align-self: center;
    background: var(--error-bg);
    color: var(--error);
    padding: 10px 16px;
    border-radius: var(--radius);
    border: 1px solid #fca5a5;
    font-size: 0.85rem;
}

.input-area {
    display: flex;
    gap: 8px;
    padding: 16px 20px;
    border-top: 1px solid var(--border);
    background: var(--bg-card);
    box-shadow: 0 -1px 4px rgba(0, 0, 0, 0.03);
    align-items: flex-end;
}

.btn-upload-image {
    padding: 10px 14px;
    background: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 1.1rem;
    transition: background 0.15s;
    flex-shrink: 0;
}
.btn-upload-image:hover { background: var(--border); }

.image-preview-area {
    padding: 8px 20px 0;
    background: var(--bg-card);
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    border-top: 1px solid var(--border);
}

.image-preview-item {
    position: relative;
    width: 80px;
    height: 80px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
}
.image-preview-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}
.image-preview-item .remove-btn {
    position: absolute;
    top: 2px;
    right: 2px;
    width: 18px;
    height: 18px;
    background: rgba(0,0,0,0.6);
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 12px;
    line-height: 1;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}
.image-preview-item .remove-btn:hover { background: var(--error); }

#message-input {
    flex: 1;
    padding: 12px 16px;
    background: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 0.95rem;
    resize: none;
    font-family: inherit;
    line-height: 1.4;
}
#message-input:focus { outline: none; border-color: var(--accent); }

.btn-send {
    padding: 12px 24px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 600;
    transition: background 0.2s;
    white-space: nowrap;
}
.btn-send:hover { background: var(--accent-hover); }
.btn-send:disabled { opacity: 0.5; cursor: not-allowed; }

.param-controls {
    padding: 8px 20px 12px;
    background: var(--bg);
    border-top: 1px solid var(--border);
    display: flex;
    gap: 24px;
}

.param-row {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.param-row input[type="range"] {
    width: 120px;
    accent-color: var(--accent);
}

.param-row input[type="number"] {
    width: 80px;
    padding: 4px 8px;
    background: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.85rem;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    z-index: 1000;
}
.modal.active { display: flex; align-items: center; justify-content: center; }

.modal-backdrop {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: rgba(0,0,0,0.25);
    backdrop-filter: blur(4px);
}

.modal-content {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    width: 600px;
    max-width: 90vw;
    max-height: 85vh;
    overflow-y: auto;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    animation: modalIn 0.2s ease-out;
}

@keyframes modalIn {
    from { opacity: 0; transform: scale(0.95); }
    to { opacity: 1; transform: scale(1); }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
    border-bottom: 1px solid var(--border);
}
.modal-header h2 { font-size: 1.1rem; }

.btn-close {
    background: none;
    border: none;
    color: var(--text);
    font-size: 1.5rem;
    cursor: pointer;
    line-height: 1;
}

.modal-body {
    padding: 20px;
}

.config-list {
    margin-bottom: 16px;
}

.config-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 8px;
    background: var(--bg);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
}
.config-item .config-info { flex: 1; }
.config-item .config-name { font-weight: 600; font-size: 0.95rem; }
.config-item .config-meta { font-size: 0.8rem; color: var(--text-muted); margin-top: 2px; }
.config-item .config-actions { display: flex; gap: 8px; }

.btn-edit, .btn-delete {
    padding: 6px 12px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: background 0.15s;
}
.btn-edit { background: var(--bg-input); color: var(--text); }
.btn-edit:hover { background: var(--border); }
.btn-delete { background: rgba(248, 113, 113, 0.2); color: var(--error); }
.btn-delete:hover { background: rgba(248, 113, 113, 0.3); }

.btn-primary {
    padding: 10px 20px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 600;
    transition: background 0.2s;
}
.btn-primary:hover { background: var(--accent-hover); }

.btn-secondary {
    padding: 10px 20px;
    background: var(--bg-input);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.95rem;
    transition: background 0.15s;
}
.btn-secondary:hover { background: var(--border); }

.config-form {
    border-top: 1px solid var(--border);
    padding-top: 16px;
    margin-top: 16px;
}
.config-form h3 { margin-bottom: 16px; font-size: 1rem; }

.form-group {
    margin-bottom: 12px;
}
.form-group label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 4px;
}
.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 8px 12px;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.9rem;
    font-family: inherit;
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
}

.form-row {
    display: flex;
    gap: 16px;
}
.form-row .form-group { flex: 1; }

.form-actions {
    display: flex;
    gap: 8px;
    margin-top: 16px;
}

.loading {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ─── Utility ─────────────────────────────────────── */

.hidden { display: none !important; }

/* ─── Login modal ─────────────────────────────────── */

.login-modal-content {
    width: 400px;
    max-width: 90vw;
}

.login-form {
    text-align: center;
}

.login-hint {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 20px;
}

#login-password {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 1rem;
    font-family: inherit;
    text-align: center;
    letter-spacing: 2px;
}
#login-password:focus {
    outline: none;
    border-color: var(--accent);
}

.login-error {
    color: var(--error);
    background: var(--error-bg);
    border: 1px solid #fca5a5;
    padding: 8px 12px;
    border-radius: var(--radius);
    margin: 12px 0;
    font-size: 0.9rem;
}

.btn-login {
    width: 100%;
    margin-top: 8px;
    padding: 12px;
    font-size: 1rem;
}

.btn-logout {
    padding: 8px 12px;
    background: transparent;
    color: var(--error);
    border: 1px solid var(--error);
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 0.85rem;
    margin-top: 8px;
    transition: background 0.15s;
    min-height: 44px;
}
.btn-logout:hover {
    background: var(--error-bg);
}

/* ─── Sidebar backdrop (mobile) ─────────────────────── */

.sidebar-backdrop {
    display: none;
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: rgba(0, 0, 0, 0.3);
    z-index: 998;
}
.sidebar-backdrop.active { display: block; }

/* ─── Hamburger menu button ─────────────────────────── */

.btn-menu-toggle {
    display: none;
    position: absolute;
    top: 8px;
    left: 8px;
    width: 44px;
    height: 44px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 1.3rem;
    cursor: pointer;
    z-index: 100;
    align-items: center;
    justify-content: center;
    color: var(--text);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

/* ─── Mobile responsive (≤ 768px) ───────────────────── */

@media (max-width: 768px) {
    .btn-menu-toggle {
        display: flex;
    }

    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        width: 280px;
        height: 100%;
        z-index: 999;
        transform: translateX(-100%);
        box-shadow: 0 0 16px rgba(0, 0, 0, 0.12);
    }

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

    .chat-area {
        margin-left: 0;
        width: 100%;
    }

    .chat-header {
        padding: 12px 20px 12px 60px;
    }

    #model-selector {
        min-width: 0;
        width: 100%;
    }

    .btn-new,
    .btn-send,
    .btn-settings {
        min-height: 44px;
    }

    .conversation-item {
        padding: 12px;
    }

    .conversation-item .delete-convo {
        opacity: 1;
    }

    .btn-edit,
    .btn-delete {
        padding: 8px 14px;
        min-width: 44px;
        min-height: 44px;
    }

    .btn-primary,
    .btn-secondary {
        min-height: 44px;
    }

    .param-controls {
        flex-direction: column;
        gap: 8px;
    }

    .param-row input[type="range"] {
        flex: 1;
    }
}

/* ─── Narrow screens (≤ 480px) ──────────────────────── */

@media (max-width: 480px) {
    .messages-container {
        padding: 12px;
        gap: 10px;
    }

    .message {
        max-width: 92%;
        padding: 10px 12px;
        font-size: 0.9rem;
    }

    .input-area {
        padding: 10px 12px;
        gap: 6px;
    }

    #message-input {
        padding: 10px 12px;
    }

    .btn-send {
        padding: 0 16px;
    }

    .chat-header {
        padding: 10px 12px 10px 56px;
    }

    .modal-content {
        width: 100%;
        max-width: 100%;
        height: 100%;
        max-height: 100%;
        border-radius: 0;
    }

    .modal-body {
        padding: 16px;
    }

    .sidebar {
        width: 100%;
    }

    .form-row {
        flex-direction: column;
        gap: 0;
    }

    .config-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .config-item .config-actions {
        align-self: flex-end;
    }
}