/* ==========================================================================
   LAYOUT.CSS - Page Layout System
   University Portal (Dogus University)
   CSS Grid / Flexbox based layout: sidebar, topbar, main content, grid.
   ========================================================================== */

/* ------------------------------------------------------------------
   APP WRAPPER
   ------------------------------------------------------------------ */
.du-app {
    display: flex;
    min-height: 100vh;
    width: 100%;
    background-color: var(--du-bg-page);
}

/* ------------------------------------------------------------------
   SIDEBAR
   ------------------------------------------------------------------ */
.du-sidebar {
    position: fixed;
    top: 0;
    left: 0;
    z-index: var(--du-z-sidebar);
    width: var(--du-sidebar-width);
    height: 100vh;
    display: flex;
    flex-direction: column;
    background-color: var(--du-bg-sidebar);
    color: var(--du-text-inverse);
    transition: width var(--du-transition-normal),
                transform var(--du-transition-normal);
    overflow: hidden;
}

/* Sidebar header - logo area */
.du-sidebar__header {
    display: flex;
    align-items: center;
    gap: var(--du-space-3);
    padding: var(--du-space-4) var(--du-space-5);
    height: var(--du-topbar-height);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    flex-shrink: 0;
}

.du-sidebar__logo {
    width: 36px;
    height: 36px;
    flex-shrink: 0;
}

.du-sidebar__logo img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.du-sidebar__brand {
    font-size: var(--du-text-md);
    font-weight: var(--du-weight-bold);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: var(--du-leading-tight);
}

.du-sidebar__brand-sub {
    display: block;
    font-size: var(--du-text-xs);
    font-weight: var(--du-weight-normal);
    opacity: 0.6;
}

/* Sidebar navigation - scrollable area */
.du-sidebar__nav {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    padding: var(--du-space-3) 0;
}

/* Nav section group */
.du-sidebar__section {
    margin-bottom: var(--du-space-2);
}

.du-sidebar__section-title {
    padding: var(--du-space-3) var(--du-space-5) var(--du-space-2);
    font-size: var(--du-text-xs);
    font-weight: var(--du-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: rgba(255, 255, 255, 0.35);
    white-space: nowrap;
    overflow: hidden;
}

/* Nav link item */
.du-sidebar__link {
    display: flex;
    align-items: center;
    gap: var(--du-space-3);
    padding: var(--du-space-2) var(--du-space-5);
    margin: 1px var(--du-space-2);
    border-radius: var(--du-radius-md);
    font-size: var(--du-text-sm);
    font-weight: var(--du-weight-medium);
    color: rgba(255, 255, 255, 0.65);
    white-space: nowrap;
    overflow: hidden;
    cursor: pointer;
    transition: background-color var(--du-transition-fast),
                color var(--du-transition-fast);
}

.du-sidebar__link:hover {
    background-color: rgba(255, 255, 255, 0.08);
    color: rgba(255, 255, 255, 0.95);
}

.du-sidebar__link--active {
    background-color: var(--du-primary);
    color: #FFFFFF;
}

.du-sidebar__link--active:hover {
    background-color: var(--du-primary-dark);
    color: #FFFFFF;
}

.du-sidebar__link-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 20px;
    height: 20px;
    flex-shrink: 0;
    font-size: var(--du-text-md);
}

.du-sidebar__link-text {
    overflow: hidden;
    text-overflow: ellipsis;
}

.du-sidebar__link-badge {
    margin-left: auto;
    padding: 2px 8px;
    font-size: var(--du-text-xs);
    font-weight: var(--du-weight-semibold);
    border-radius: var(--du-radius-full);
    background-color: var(--du-primary);
    color: #FFFFFF;
    flex-shrink: 0;
}

.du-sidebar__link--active .du-sidebar__link-badge {
    background-color: rgba(255, 255, 255, 0.25);
}

/* Sidebar footer */
.du-sidebar__footer {
    padding: var(--du-space-4) var(--du-space-5);
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    flex-shrink: 0;
}

/* Sidebar divider */
.du-sidebar__divider {
    height: 1px;
    margin: var(--du-space-2) var(--du-space-5);
    background-color: rgba(255, 255, 255, 0.08);
}

/* Sidebar mobile overlay backdrop */
.du-sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    z-index: calc(var(--du-z-sidebar) - 1);
    background-color: rgba(0, 0, 0, 0.5);
    opacity: 0;
    transition: opacity var(--du-transition-normal);
}

.du-sidebar-overlay--visible {
    display: block;
    opacity: 1;
}

/* ------------------------------------------------------------------
   TOPBAR
   ------------------------------------------------------------------ */
.du-topbar {
    position: fixed;
    top: 0;
    left: var(--du-sidebar-width);
    right: 0;
    z-index: var(--du-z-topbar);
    height: var(--du-topbar-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--du-space-6);
    background-color: var(--du-bg-card);
    border-bottom: 1px solid var(--du-border-color);
    transition: left var(--du-transition-normal);
}

.du-topbar__left {
    display: flex;
    align-items: center;
    gap: var(--du-space-4);
}

.du-topbar__hamburger {
    display: none;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: var(--du-radius-md);
    color: var(--du-text-secondary);
    cursor: pointer;
    transition: background-color var(--du-transition-fast);
}

.du-topbar__hamburger:hover {
    background-color: var(--du-bg-hover);
}

.du-topbar__right {
    display: flex;
    align-items: center;
    gap: var(--du-space-2);
}

/* Topbar search */
.du-topbar__search {
    position: relative;
    width: 240px;
}

.du-topbar__search-input {
    width: 100%;
    padding: var(--du-space-2) var(--du-space-3);
    padding-left: var(--du-space-9);
    background-color: var(--du-bg-page);
    border: 1px solid var(--du-border-color);
    border-radius: var(--du-radius-md);
    font-size: var(--du-text-sm);
    color: var(--du-text-primary);
    transition: border-color var(--du-transition-fast),
                box-shadow var(--du-transition-fast);
}

.du-topbar__search-input::placeholder {
    color: var(--du-text-muted);
}

.du-topbar__search-input:focus {
    outline: none;
    border-color: var(--du-primary);
    box-shadow: var(--du-focus-ring);
}

.du-topbar__search-icon {
    position: absolute;
    left: var(--du-space-3);
    top: 50%;
    transform: translateY(-50%);
    color: var(--du-text-muted);
    pointer-events: none;
}

/* Topbar icon button (notifications, theme toggle) */
.du-topbar__icon-btn {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--du-radius-md);
    color: var(--du-text-secondary);
    cursor: pointer;
    transition: background-color var(--du-transition-fast),
                color var(--du-transition-fast);
}

.du-topbar__icon-btn:hover {
    background-color: var(--du-bg-hover);
    color: var(--du-text-primary);
}

.du-topbar__icon-btn .du-notification-dot {
    position: absolute;
    top: 8px;
    right: 8px;
    width: 8px;
    height: 8px;
    border-radius: var(--du-radius-full);
    background-color: var(--du-danger);
    border: 2px solid var(--du-bg-card);
}

/* Topbar user area */
.du-topbar__user {
    display: flex;
    align-items: center;
    gap: var(--du-space-3);
    padding: var(--du-space-1) var(--du-space-2);
    border-radius: var(--du-radius-md);
    cursor: pointer;
    transition: background-color var(--du-transition-fast);
}

.du-topbar__user:hover {
    background-color: var(--du-bg-hover);
}

.du-topbar__user-info {
    text-align: right;
    line-height: var(--du-leading-tight);
}

.du-topbar__user-name {
    font-size: var(--du-text-sm);
    font-weight: var(--du-weight-semibold);
    color: var(--du-text-primary);
}

.du-topbar__user-role {
    font-size: var(--du-text-xs);
    color: var(--du-text-muted);
}

/* ------------------------------------------------------------------
   MAIN CONTENT AREA
   ------------------------------------------------------------------ */
.du-main {
    margin-left: var(--du-sidebar-width);
    margin-top: var(--du-topbar-height);
    padding: var(--du-space-6);
    min-height: calc(100vh - var(--du-topbar-height));
    width: calc(100% - var(--du-sidebar-width));
    transition: margin-left var(--du-transition-normal),
                width var(--du-transition-normal);
}

/* Page header */
.du-page-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--du-space-4);
    margin-bottom: var(--du-space-6);
}

.du-page-header__title {
    font-size: var(--du-text-2xl);
    font-weight: var(--du-weight-bold);
    color: var(--du-text-primary);
    line-height: var(--du-leading-tight);
}

.du-page-header__subtitle {
    font-size: var(--du-text-sm);
    color: var(--du-text-secondary);
    margin-top: var(--du-space-1);
}

.du-page-header__actions {
    display: flex;
    align-items: center;
    gap: var(--du-space-3);
}

/* Content wrapper */
.du-content {
    max-width: var(--du-content-max-width);
    width: 100%;
}

.du-content--full {
    max-width: 100%;
}

/* ------------------------------------------------------------------
   GRID SYSTEM
   ------------------------------------------------------------------ */
.du-grid {
    display: grid;
    gap: var(--du-space-6);
}

.du-grid--gap-sm {
    gap: var(--du-space-3);
}

.du-grid--gap-md {
    gap: var(--du-space-4);
}

.du-grid--gap-lg {
    gap: var(--du-space-8);
}

.du-grid--2 {
    grid-template-columns: repeat(2, 1fr);
}

.du-grid--3 {
    grid-template-columns: repeat(3, 1fr);
}

.du-grid--4 {
    grid-template-columns: repeat(4, 1fr);
}

.du-grid--auto-fill {
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

/* Spans */
.du-col-span-2 {
    grid-column: span 2;
}

.du-col-span-3 {
    grid-column: span 3;
}

.du-col-span-full {
    grid-column: 1 / -1;
}

/* ------------------------------------------------------------------
   FLEX UTILITIES (layout-level)
   ------------------------------------------------------------------ */
.du-flex {
    display: flex;
}

.du-flex--wrap {
    flex-wrap: wrap;
}

.du-flex--col {
    flex-direction: column;
}

.du-flex--center {
    align-items: center;
    justify-content: center;
}

.du-flex--between {
    justify-content: space-between;
}

.du-flex--end {
    justify-content: flex-end;
}

.du-flex--gap-sm {
    gap: var(--du-space-2);
}

.du-flex--gap {
    gap: var(--du-space-4);
}

.du-flex--gap-lg {
    gap: var(--du-space-6);
}

.du-items-center {
    align-items: center;
}

.du-items-start {
    align-items: flex-start;
}

/* ------------------------------------------------------------------
   SECTION WRAPPERS
   ------------------------------------------------------------------ */
.du-section {
    margin-bottom: var(--du-space-6);
}

.du-section__title {
    font-size: var(--du-text-lg);
    font-weight: var(--du-weight-semibold);
    color: var(--du-text-primary);
    margin-bottom: var(--du-space-4);
}

.du-section__description {
    font-size: var(--du-text-sm);
    color: var(--du-text-secondary);
    margin-bottom: var(--du-space-4);
}

/* ------------------------------------------------------------------
   BREADCRUMB (layout context)
   ------------------------------------------------------------------ */
.du-breadcrumb {
    display: flex;
    align-items: center;
    gap: var(--du-space-2);
    font-size: var(--du-text-sm);
    color: var(--du-text-secondary);
}

.du-breadcrumb__item {
    display: flex;
    align-items: center;
    gap: var(--du-space-2);
}

.du-breadcrumb__item::before {
    content: '/';
    color: var(--du-text-muted);
}

.du-breadcrumb__item:first-child::before {
    content: none;
}

.du-breadcrumb__link {
    color: var(--du-text-secondary);
    transition: color var(--du-transition-fast);
}

.du-breadcrumb__link:hover {
    color: var(--du-primary);
}

.du-breadcrumb__current {
    color: var(--du-text-primary);
    font-weight: var(--du-weight-medium);
}

/* ------------------------------------------------------------------
   VISIBILITY HELPERS
   ------------------------------------------------------------------ */
.du-hide-mobile {
    /* shown by default; hidden via responsive.css on mobile */
}

.du-show-mobile {
    display: none !important;
}

/* ------------------------------------------------------------------
   RESPONSIVE BREAKPOINTS
   ------------------------------------------------------------------ */

/* Tablet and below */
@media (max-width: 1024px) {
    .du-grid--2 {
        grid-template-columns: 1fr;
    }

    .du-grid--3 {
        grid-template-columns: repeat(2, 1fr);
    }

    .du-grid--4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Mobile */
@media (max-width: 768px) {
    /* Sidebar: hidden by default on mobile, slides in */
    .du-sidebar {
        transform: translateX(-100%);
    }

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

    /* Topbar: full width */
    .du-topbar {
        left: 0;
    }

    /* Hamburger visible */
    .du-topbar__hamburger {
        display: flex;
    }

    /* Hide user info text on mobile */
    .du-topbar__user-info {
        display: none;
    }

    /* Main content: full width */
    .du-main {
        margin-left: 0;
        width: 100%;
        padding: var(--du-space-4);
    }

    /* Grids become single column */
    .du-grid--2,
    .du-grid--3,
    .du-grid--4 {
        grid-template-columns: 1fr;
    }

    .du-col-span-2,
    .du-col-span-3 {
        grid-column: span 1;
    }

    /* Show mobile elements */
    .du-show-mobile {
        display: flex !important;
    }

    .du-hide-mobile {
        display: none !important;
    }
}

.du-sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}