/* ==========================================================================
   Navigation Styles
   Contract: CSS Contract v1.0
   ========================================================================== */

/* CSS Variables (COL-002) */
:root {
    --nav-bg: #2c3e50;
    --nav-text: #fff;
    --nav-hover-bg: rgba(255, 255, 255, 0.1);
    --nav-dropdown-bg: #fff;
    --nav-dropdown-text: #333;
    --nav-dropdown-hover-bg: #f8f9fa;
    --nav-dropdown-border: #eee;
    --nav-focus-color: #3498db;
}

/* Main Navigation Container */
.main-nav {
    display: flex;
    align-items: center;
    padding: 0 1rem;
    background-color: var(--nav-bg);
}

/* Brand / Logo */
.nav-brand {
    color: var(--nav-text);
    background-color: transparent;
    text-decoration: none;
    font-weight: 700;
    font-size: 1.1rem;
    padding: 1rem;
    margin-right: 1rem;
}

.nav-brand:hover {
    background-color: var(--nav-hover-bg);
}

.nav-brand:focus {
    outline: 2px solid var(--nav-focus-color);
    outline-offset: -2px;
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    background: transparent;
    border: none;
    color: var(--nav-text);
    padding: 1rem;
    cursor: pointer;
    margin-left: auto;
}

.nav-toggle:focus {
    outline: 2px solid var(--nav-focus-color);
    outline-offset: -2px;
}

.nav-toggle-icon {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--nav-text);
    position: relative;
}

.nav-toggle-icon::before,
.nav-toggle-icon::after {
    content: '';
    position: absolute;
    width: 24px;
    height: 2px;
    background-color: var(--nav-text);
    left: 0;
}

.nav-toggle-icon::before { top: -7px; }
.nav-toggle-icon::after { top: 7px; }

/* Desktop Navigation Items Container */
.nav-items {
    display: flex;
    align-items: center;
    gap: 0;
}

/* Dropdown Container */
.nav-dropdown {
    position: relative;
}

/* Dropdown Button */
.nav-dropdown-btn {
    background-color: transparent;
    border: none;
    color: var(--nav-text);
    padding: 1rem 1.25rem;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    font-family: inherit;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-dropdown-btn::after {
    content: '';
    border: solid var(--nav-text);
    border-width: 0 2px 2px 0;
    padding: 3px;
    transform: rotate(45deg);
    margin-top: -3px;
}

.nav-dropdown-btn:hover,
.nav-dropdown:hover .nav-dropdown-btn,
.nav-dropdown.active .nav-dropdown-btn {
    background-color: var(--nav-hover-bg);
}

.nav-dropdown-btn:focus {
    outline: 2px solid var(--nav-focus-color);
    outline-offset: -2px;
}

/* Dropdown Content */
.nav-dropdown-content {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: var(--nav-dropdown-bg);
    min-width: 200px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    border-radius: 0 0 6px 6px;
    z-index: 1000;
}

/* Show on hover (desktop) and when active (mobile/keyboard) */
.nav-dropdown:hover .nav-dropdown-content,
.nav-dropdown.active .nav-dropdown-content {
    display: block;
}

/* Dropdown Links */
.nav-dropdown-content a {
    display: block;
    padding: 0.75rem 1.25rem;
    color: var(--nav-dropdown-text);
    background-color: var(--nav-dropdown-bg);
    text-decoration: none;
    font-weight: 500;
    border-bottom: 1px solid var(--nav-dropdown-border);
}

.nav-dropdown-content a:last-child {
    border-bottom: none;
    border-radius: 0 0 6px 6px;
}

.nav-dropdown-content a:hover {
    background-color: var(--nav-dropdown-hover-bg);
    color: var(--nav-bg);
}

.nav-dropdown-content a:focus {
    outline: 2px solid var(--nav-focus-color);
    outline-offset: -2px;
}

/* External link indicator */
.nav-dropdown-content a[target="_blank"]::after {
    content: ' \2197';
    font-size: 0.8em;
}

/* ==========================================================================
   Mobile Styles (RES-001: Mobile-First Breakpoints)
   ========================================================================== */

@media (max-width: 768px) {
    .main-nav {
        flex-wrap: wrap;
    }

    .nav-toggle {
        display: block;
    }

    .nav-items {
        display: none;
        flex-direction: column;
        width: 100%;
        align-items: stretch;
    }

    .nav-items.open {
        display: flex;
    }

    .nav-dropdown {
        width: 100%;
    }

    .nav-dropdown-btn {
        width: 100%;
        justify-content: space-between;
        padding: 1rem 1.5rem;
    }

    .nav-dropdown-content {
        position: static;
        box-shadow: none;
        border-radius: 0;
        background-color: rgba(0, 0, 0, 0.1);
    }

    .nav-dropdown-content a {
        padding-left: 2.5rem;
        background-color: transparent;
        color: var(--nav-text);
        border-bottom-color: rgba(255, 255, 255, 0.1);
    }

    .nav-dropdown-content a:hover {
        background-color: var(--nav-hover-bg);
        color: var(--nav-text);
    }

    .nav-dropdown-content a:last-child {
        border-radius: 0;
    }
}