/* ==========================================================================
   HEADER & NAVIGATION
   ========================================================================== */

/* --------------------------------------------------------------------------
   Site Header
   -------------------------------------------------------------------------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 500;
    height: var(--header-height);
    border-bottom: 1px solid var(--color-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    /* Light mode default */
    background: rgba(242, 244, 243, 0.94);
    transition: background-color 300ms ease, border-color 300ms ease, box-shadow var(--transition-base);
}

.site-header.is-scrolled {
    box-shadow: 0 2px 20px var(--color-shadow);
}

/* Dark mode — manual toggle */
[data-theme="dark"] .site-header {
    background: rgba(26, 31, 46, 0.94);
}

/* Dark mode — OS preference */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .site-header {
        background: rgba(26, 31, 46, 0.94);
    }
}

.site-header .container {
    height: 100%;
}

/* Flexbox header: logo left | nav center | actions right */
.site-header__inner {
    display: flex;
    align-items: center;
    height: 100%;
    gap: var(--space-md);
}

/* --------------------------------------------------------------------------
   Logo / Site Identity
   -------------------------------------------------------------------------- */
.site-branding {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    flex-shrink: 0;
    text-decoration: none;
}

.site-logo img {
    height: 57px;
    width: auto;
}

/* Light mode: show light logo, hide dark logo */
.site-logo__dark  { display: none; }
.site-logo__light { display: block; }

/* Dark mode — manual toggle */
[data-theme="dark"] .site-logo__light { display: none; }
[data-theme="dark"] .site-logo__dark  { display: block; }

/* Dark mode — OS preference */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .site-logo__light { display: none; }
    :root:not([data-theme="light"]) .site-logo__dark  { display: block; }
}

.site-name {
    font-family: var(--font-serif);
    font-size: 1.35rem;
    font-weight: 900;
    font-style: italic;
    color: var(--color-heading);
    letter-spacing: -0.02em;
    line-height: 1;
    transition: color var(--transition-fast);
}

.site-name em {
    font-style: normal;
    color: var(--color-accent);
}

.site-branding:hover .site-name { color: var(--color-accent); }

/* --------------------------------------------------------------------------
   Primary Navigation
   -------------------------------------------------------------------------- */
.primary-nav {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
}

.nav__menu {
    display: flex;
    align-items: center;
    gap: 0;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav__item {
    position: relative;
}

.nav__link {
    display: flex;
    align-items: center;
    gap: 0.25em;
    padding: 0.5rem 0.9rem;
    font-family: var(--font-ui);
    font-size: 0.875rem;
    font-weight: 500;
    /* Explicit contrast in light mode */
    color: #1E2D2A;
    text-decoration: none;
    border-radius: var(--radius-md);
    white-space: nowrap;
    transition: color var(--transition-fast), background-color var(--transition-fast);
    line-height: 1;
}

/* Dark mode top-level nav links */
[data-theme="dark"] .primary-nav > .nav__menu > .nav__item > .nav__link,
[data-theme="dark"] .primary-nav > .nav__menu > .nav__item > .nav__link {
    color: #E8EEF4;
}
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .primary-nav > .nav__menu > .nav__item > .nav__link {
        color: #E8EEF4;
    }
}

.nav__link:hover,
.nav__item:hover > .nav__link {
    color: var(--color-accent);
    background: var(--color-accent-light);
}

.nav__link.is-active {
    color: var(--color-accent);
    font-weight: 600;
}

/* Dropdown arrow */
.nav__item--has-children > .nav__link::after {
    content: '';
    display: inline-block;
    width: 0;
    height: 0;
    border-left: 4px solid transparent;
    border-right: 4px solid transparent;
    border-top: 5px solid currentColor;
    transition: transform var(--transition-fast);
    margin-left: 0.1em;
}

.nav__item--has-children:hover > .nav__link::after {
    transform: rotate(180deg);
}

/* --------------------------------------------------------------------------
   Dropdown
   -------------------------------------------------------------------------- */

/* Transparent bridge that fills the gap between the nav link and dropdown,
   preventing the hover state from being lost as the cursor moves down */
.nav__dropdown::before {
    content: '';
    position: absolute;
    top: -8px;
    left: 0;
    right: 0;
    height: 8px;
}

.nav__dropdown {
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    min-width: 210px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: 0 8px 32px var(--color-shadow-md);
    padding: var(--space-xs) 0;
    list-style: none;
    margin: 0;
    /* Hidden: use both visibility + opacity so it's truly inaccessible when closed */
    visibility: hidden;
    opacity: 0;
    pointer-events: none;
    transform: translateY(-6px);
    transition:
        visibility 0s linear var(--transition-base),
        opacity var(--transition-base),
        transform var(--transition-base);
    z-index: 200;
}

.nav__item--has-children:hover > .nav__dropdown,
.nav__item--has-children:focus-within > .nav__dropdown {
    visibility: visible;
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
    /* Remove the visibility delay when showing */
    transition:
        visibility 0s linear 0s,
        opacity var(--transition-base),
        transform var(--transition-base);
}

.nav__dropdown .nav__link {
    padding: 0.6rem 1.1rem;
    font-size: 0.84rem;
    font-weight: 400;
    color: var(--color-text);
    border-radius: 0;
    width: 100%;
    white-space: nowrap;
}

.nav__dropdown .nav__link:hover {
    color: var(--color-accent);
    background: var(--color-accent-light);
    padding-left: 1.4rem;
}

/* --------------------------------------------------------------------------
   Submit an Article button
   -------------------------------------------------------------------------- */
.submit-article-btn {
    display: inline-flex;
    align-items: center;
    padding: 0.45rem 1rem;
    font-family: var(--font-ui);
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    white-space: nowrap;
    color: #fff;
    background: var(--color-accent);
    border-radius: var(--radius-md);
    text-decoration: none;
    transition: background var(--transition-fast), opacity var(--transition-fast);
}

.submit-article-btn:hover {
    opacity: 0.88;
    color: #fff;
}

/* Hide on small screens to keep header tidy */
@media (max-width: 640px) {
    .submit-article-btn {
        display: none;
    }
}

/* --------------------------------------------------------------------------
   Header Actions (search + dark toggle)
   -------------------------------------------------------------------------- */
.header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    flex-shrink: 0;
    margin-left: auto;
}

/* Search trigger */
.header-search-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 38px;
    height: 38px;
    border: none;
    background: transparent;
    border-radius: var(--radius-md);
    color: var(--color-text-muted);
    cursor: pointer;
    transition: color var(--transition-fast), background var(--transition-fast);
}

.header-search-btn:hover {
    color: var(--color-accent);
    background: var(--color-accent-light);
}

.header-search-btn svg {
    width: 18px;
    height: 18px;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
}

/* Dark mode toggle */
.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 38px;
    height: 38px;
    border: 1px solid var(--color-border);
    background: var(--color-bg-subtle);
    border-radius: var(--radius-md);
    color: var(--color-text-muted);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
    background: var(--color-accent-light);
}

.theme-toggle svg {
    width: 16px;
    height: 16px;
}

/* Moon icon — solid crescent, used in dark mode */
.theme-toggle .icon-moon {
    display: none;
    fill: currentColor;
    stroke: none;
}

/* Sun icon — outline style with rays, used in light mode */
.theme-toggle .icon-sun {
    display: block;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
}

[data-theme="dark"] .theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun  { display: none; }

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .theme-toggle .icon-moon { display: block; }
    :root:not([data-theme="light"]) .theme-toggle .icon-sun  { display: none; }
}

/* --------------------------------------------------------------------------
   Mobile Menu Toggle
   -------------------------------------------------------------------------- */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 38px;
    height: 38px;
    padding: 8px;
    border: 1px solid var(--color-border);
    background: transparent;
    border-radius: var(--radius-md);
    cursor: pointer;
}

.mobile-menu-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: transform var(--transition-base), opacity var(--transition-base);
}

.mobile-menu-toggle[aria-expanded="true"] span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.mobile-menu-toggle[aria-expanded="true"] span:nth-child(2) {
    opacity: 0;
}
.mobile-menu-toggle[aria-expanded="true"] span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   Responsive — Tablet
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
    .primary-nav {
        display: none;
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        bottom: 0;
        background: var(--color-bg);
        flex-direction: column;
        justify-content: flex-start;
        align-items: stretch;
        padding: var(--space-lg);
        overflow-y: auto;
        z-index: 400;
        animation: slideDown 200ms ease;
    }

    .primary-nav.is-open {
        display: flex;
    }

    .nav__menu {
        flex-direction: column;
        align-items: stretch;
        gap: 0;
    }

    .nav__link {
        font-size: 1.1rem;
        padding: 0.75rem 1rem;
        justify-content: space-between;
    }

    .nav__item--has-children > .nav__link::after {
        margin-left: auto;
    }

    .nav__dropdown {
        position: static;
        box-shadow: none;
        border: none;
        border-left: 3px solid var(--color-accent);
        border-radius: 0;
        margin-left: var(--space-lg);
        /* Override desktop hidden state — mobile uses display toggle */
        visibility: visible;
        opacity: 1;
        pointer-events: auto;
        transform: none;
        transition: none;
        display: none;
        padding: var(--space-xs) 0;
        background: transparent;
    }

    .nav__item--has-children.is-open > .nav__dropdown {
        display: block;
    }

    /* Mobile nav link colors — always dark on the overlay bg */
    .nav__link {
        color: var(--color-text);
    }

    .nav__dropdown .nav__link {
        font-size: 0.95rem;
        padding: 0.6rem 1rem;
    }

    .mobile-menu-toggle {
        display: flex;
    }
}

@media (max-width: 640px) {
    .site-name {
        font-size: 1.1rem;
    }

    .site-logo img {
        height: 29px;
        max-width: 180px;
        width: auto;
    }
}