:root {
    --sidebar-width: 280px;
    --header-height: 60px;
}

body {
    margin: 0;
}

/* Mobile Header (visible only on small screens) */
.mobile-header {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: #ffffff;
    border-bottom: 1px solid #e5e5e5;
    padding: 0 20px;
    align-items: center;
    justify-content: space-between;
    z-index: 1000;
}

.hamburger {
    display: flex;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.hamburger span {
    display: block;
    width: 24px;
    height: 2px;
    background: #171717;
    transition: all 0.3s;
}

.hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(4px, 4px);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

/* Sidebar */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--sidebar-width);
    height: 100vh;
    background: #fafafa;
    border-right: 1px solid #e5e5e5;
    overflow-y: auto;
    z-index: 999;
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid #e5e5e5;
}

.sidebar-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: #171717;
    user-select: none;
}

/* Search */
.sidebar-search {
    padding: 16px 20px;
    border-bottom: 1px solid #e5e5e5;
}

.sidebar-search input {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid #e5e5e5;
    border-radius: 6px;
    font-size: 0.9rem;
    background: #ffffff;
}

.sidebar-search input:focus {
    outline: none;
    border-color: #15803d;
}

/* Navigation */
.sidebar-nav {
    flex: 1;
    padding: 20px 0;
    overflow-y: auto;
    opacity: 0;
    transition: opacity 0.3s ease-in;
}

.sidebar-nav.loaded {
    opacity: 1;
}

/* Prevent layout shift - reserve space for nav */
.sidebar-nav:empty {
    min-height: 200px;
}

.nav-category {
    margin-bottom: 24px;
}

.nav-category h3 {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: #737373;
    padding: 0 20px;
    margin-bottom: 8px;
}

.nav-category ul {
    list-style: none;
}

.nav-category li {
    margin: 2px 0;
}

.nav-category a {
    display: block;
    padding: 8px 20px;
    color: #171717;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.nav-category a:hover {
    background: #f5f5f5;
    color: #15803d;
}

.nav-category a.active {
    background: #eff6ff;
    color: #15803d;
}

/* Hidden when filtered */
.nav-category.hidden {
    display: none;
}

/* Overlay (mobile only) */
.sidebar-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 998;
}

/* Main Content */
.main-content {
    margin-left: var(--sidebar-width);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Content wrapper grows to push footer down */
.content-wrapper {
    flex: 1;
    padding: 40px;
}

.page-header {
    max-width: 800px;
    margin: 0 auto 40px;
}

.tool-container {
    max-width: 800px;
    margin: 0 auto;
}

/* Responsive - Mobile */
@media (max-width: 968px) {
    .mobile-header {
        display: flex;
    }

    .sidebar {
        transform: translateX(-100%);
        transition: transform 0.3s;
    }

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

    .sidebar-overlay.show {
        display: block;
    }

    .main-content {
        margin-left: 0;
    }

    .content-wrapper {
        padding: 20px;
        margin-top: var(--header-height);
    }
}