:root {
    --sidebar-width: 230px;
    --sidebar-width-collapsed: 64px;
    --sidebar-bg: #1f2937;
    --sidebar-fg: #e5e7eb;
    --sidebar-fg-muted: #9ca3af;
    --sidebar-active-bg: #374151;
}

* {
    box-sizing: border-box;
}

html, body {
    height: 100%;
}

body {
    margin: 0;
}

.app-shell {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: var(--sidebar-width);
    background: var(--sidebar-bg);
    color: var(--sidebar-fg);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    transition: width .18s ease;
    overflow-x: hidden;
    white-space: nowrap;
}

.sidebar.collapsed {
    width: var(--sidebar-width-collapsed);
}

.sidebar-header {
    display: flex;
    align-items: center;
    gap: .75rem;
    padding: 1rem .9rem;
    border-bottom: 1px solid rgba(255,255,255,.08);
}

.sidebar-toggle-btn {
    background: transparent;
    border: none;
    color: var(--sidebar-fg);
    font-size: 1.25rem;
    line-height: 1;
    padding: .25rem;
    cursor: pointer;
}

.sidebar-brand {
    font-weight: 600;
    font-size: 1.1rem;
}

.sidebar-nav {
    flex: 1 1 auto;
    padding: .75rem 0;
    display: flex;
    flex-direction: column;
    gap: .1rem;
}

.sidebar-link {
    display: flex;
    align-items: center;
    gap: .9rem;
    padding: .65rem .95rem;
    color: var(--sidebar-fg);
    text-decoration: none;
    font-size: .95rem;
}

.sidebar-link i {
    font-size: 1.2rem;
    width: 1.2rem;
    text-align: center;
    flex-shrink: 0;
}

.sidebar-link:hover {
    background: var(--sidebar-active-bg);
    color: #fff;
}

.sidebar-footer {
    border-top: 1px solid rgba(255,255,255,.08);
    padding: .5rem 0;
}

.sidebar-user {
    display: flex;
    align-items: center;
    gap: .9rem;
    padding: .65rem .95rem;
    color: var(--sidebar-fg-muted);
    font-size: .9rem;
}

.sidebar-user i {
    font-size: 1.2rem;
    width: 1.2rem;
    text-align: center;
}

.sidebar.collapsed .nav-text,
.sidebar.collapsed .sidebar-brand {
    display: none;
}

.main-area {
    flex: 1 1 auto;
    min-width: 0;
    background: #f8f9fa;
}

.content-area {
    padding: 1.5rem;
}