:root {
    --cad-bg: #f4f5f8;
    --cad-panel: #ffffff;
    --cad-sidebar: #e9ebf0;
    --cad-border: #d2d6de;
    --cad-border-light: #e6e8ec;
    --cad-text: #1d2129;
    --cad-text-muted: #656d78;
    --cad-blue: #0284c7;
    --cad-blue-hover: #0369a1;
    --cad-green: #058548;
    --cad-green-hover: #046a38;
    --cad-accent: #0066cc;
    --cad-danger: #d9383a;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
    background: var(--cad-bg);
    color: var(--cad-text);
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* Header */
.hub-header {
    height: 48px;
    background: var(--cad-panel);
    border-bottom: 1px solid var(--cad-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    z-index: 10;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 700;
    font-size: 15px;
    letter-spacing: -0.3px;
    color: #111;
}

.brand-badge {
    background: #0f172a;
    color: #fff;
    padding: 2px 6px;
    border-radius: 3px;
    font-size: 10px;
    letter-spacing: 0.5px;
}

/* Navigation Tabs */
.hub-tabs {
    display: flex;
    gap: 4px;
    height: 100%;
    align-items: center;
}

.tab-btn {
    background: transparent;
    border: none;
    padding: 6px 14px;
    font-size: 13px;
    font-weight: 600;
    color: var(--cad-text-muted);
    cursor: pointer;
    border-radius: 4px;
    transition: all 0.15s ease;
}

.tab-btn:hover {
    color: var(--cad-text);
    background: #f0f2f5;
}

.tab-btn.active {
    color: var(--cad-accent);
    background: #eef2ff;
}

/* App Shell */
.hub-body {
    flex: 1;
    display: flex;
    overflow: hidden;
}

/* Sidebar Navigation */
.hub-sidebar {
    width: 340px;
    background: var(--cad-sidebar);
    border-right: 1px solid var(--cad-border);
    display: flex;
    flex-direction: column;
}

.sidebar-tools {
    padding: 14px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    border-bottom: 1px solid var(--cad-border);
}

.search-input {
    width: 100%;
    padding: 8px 12px;
    background: #fff;
    border: 1px solid var(--cad-border);
    border-radius: 4px;
    font-size: 13px;
    outline: none;
}

.search-input:focus {
    border-color: var(--cad-accent);
}

.model-list {
    flex: 1;
    overflow-y: auto;
    padding: 8px;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.model-item {
    background: var(--cad-panel);
    border: 1px solid var(--cad-border-light);
    border-radius: 4px;
    padding: 12px;
    cursor: pointer;
    transition: all 0.15s ease;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.model-item:hover {
    border-color: var(--cad-border);
    box-shadow: 0 2px 6px rgba(0,0,0,0.04);
}

.model-item.active {
    border-color: var(--cad-accent);
    border-left: 4px solid var(--cad-accent);
}

.model-title {
    font-weight: 600;
    font-size: 13px;
    color: #111;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.model-meta {
    font-size: 11px;
    color: var(--cad-text-muted);
    display: flex;
    gap: 10px;
}

/* Workspace */
.hub-workspace {
    flex: 1;
    background: var(--cad-bg);
    display: flex;
    flex-direction: column;
    padding: 24px;
    overflow-y: auto;
}

.hub-card {
    background: #fff;
    border: 1px solid var(--cad-border);
    border-radius: 4px;
    padding: 24px;
    max-width: 800px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin-top: 8px;
}

.feature-card {
    background: #ffffff;
    border: 1px solid var(--cad-border);
    border-radius: 6px;
    padding: 20px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
    display: flex;
    flex-direction: column;
    gap: 8px;
    transition: transform 0.15s, box-shadow 0.15s;
}

.feature-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.feature-icon {
    font-size: 24px;
}

.feature-title {
    font-size: 14px;
    font-weight: 700;
    color: #0f172a;
}

.feature-desc {
    font-size: 12px;
    line-height: 1.55;
    color: var(--cad-text-muted);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 8px 16px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    border: 1px solid transparent;
    transition: background 0.15s;
    text-decoration: none;
}

.btn-primary {
    background: var(--cad-blue);
    color: #fff;
}
.btn-primary:hover { background: var(--cad-blue-hover); }

.btn-success {
    background: var(--cad-green);
    color: #fff;
}
.btn-success:hover { background: var(--cad-green-hover); }

.btn-outline {
    background: #fff;
    border-color: var(--cad-border);
    color: var(--cad-text);
}
.btn-outline:hover { background: #f0f2f5; }

/* Progress */
.progress-bar-wrap {
    height: 6px;
    background: #e6e8ec;
    border-radius: 3px;
    overflow: hidden;
    margin-top: 6px;
}
.progress-bar-fill {
    height: 100%;
    background: var(--cad-blue);
    width: 0%;
    transition: width 0.2s;
}

.btn-danger {
    background: var(--cad-danger);
    color: #fff;
}
.btn-danger:hover {
    background: #b9292b;
}