/* ============================================
   ARCHIVE PAGE
   ============================================ */

.archive-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 24px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.archive-header-text h1 {
    font-size: 28px;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.archive-header-text h1 i {
    color: var(--text-secondary);
    font-size: 24px;
}

.archive-header-text p {
    color: var(--text-secondary);
    font-size: 15px;
}

.archive-header-actions {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-shrink: 0;
    flex-wrap: wrap;
}

.archive-stats-row {
    display: flex;
    gap: 16px;
}

.archive-stat {
    text-align: center;
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 10px;
    padding: 12px 20px;
    min-width: 72px;
}

.archive-stat-num {
    display: block;
    font-size: 22px;
    font-weight: 800;
    color: var(--text-primary);
}

.archive-stat-label {
    display: block;
    font-size: 11px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-top: 2px;
}

/* Add Problem button */
.archive-add-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--accent-primary);
    color: var(--bg-primary);
    border: none;
    border-radius: 10px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s, transform 0.15s;
    white-space: nowrap;
}

.archive-add-btn:hover {
    opacity: 0.85;
    transform: translateY(-1px);
}

/* Layout */
.archive-layout {
    display: grid;
    grid-template-columns: 268px 1fr;
    gap: 28px;
    align-items: start;
}

/* ── Filter panel ─────────────────────────────── */
.archive-filters {
    position: sticky;
    top: 110px;
}

.filter-panel {
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 12px;
    overflow: hidden;
}

/* Header is now a button for collapse */
.filter-panel-header {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 18px;
    font-weight: 700;
    font-size: 14px;
    color: var(--text-primary);
    border: none;
    border-bottom: 1px solid var(--border-primary);
    background: var(--bg-tertiary);
    cursor: pointer;
    text-align: left;
    transition: background 0.15s;
}

.filter-panel-header:hover {
    background: var(--interactive-hover);
}

.filter-panel-header span i {
    margin-right: 8px;
    color: var(--text-secondary);
}

.filter-toggle-icons {
    display: flex;
    align-items: center;
    gap: 8px;
}

.filter-active-count {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent-primary);
    color: var(--bg-primary);
    font-size: 10px;
    font-weight: 700;
}

.filter-chevron {
    color: var(--text-secondary);
    font-size: 12px;
    transition: transform 0.25s ease;
}

.filter-body {
    /* collapsible — JS sets display:none to collapse */
    overflow: hidden;
}

.filter-section {
    padding: 14px 18px;
    border-bottom: 1px solid var(--border-primary);
}

.filter-section:last-child {
    border-bottom: none;
}

.filter-section-reset {
    padding: 12px 18px;
}

.filter-label {
    display: block;
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-secondary);
    margin-bottom: 10px;
}

.filter-input {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 14px;
    outline: none;
    transition: border-color 0.2s;
    font-family: inherit;
}

.filter-input:focus {
    border-color: var(--accent-primary);
}

.filter-search-wrap {
    position: relative;
}

.filter-search-wrap > i {
    position: absolute;
    left: 10px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    font-size: 13px;
    pointer-events: none;
}

.filter-search-wrap .filter-input {
    padding-left: 32px;
}

.filter-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.filter-chip {
    padding: 5px 12px;
    border-radius: 20px;
    border: 1px solid var(--border-primary);
    background: var(--bg-primary);
    color: var(--text-secondary);
    font-size: 13px;
    cursor: pointer;
    transition: all 0.18s;
    white-space: nowrap;
}

.filter-chip:hover {
    border-color: var(--text-muted);
    color: var(--text-primary);
}

.filter-chip.active {
    background: var(--accent-primary);
    color: var(--bg-primary);
    border-color: var(--accent-primary);
    font-weight: 600;
}

/* ── Difficulty buttons (premium style) ──────── */
.diff-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 6px;
}

.diff-btn {
    display: flex;
    align-items: center;
    gap: 7px;
    padding: 7px 12px;
    border-radius: 8px;
    border: 1.5px solid var(--border-primary);
    background: var(--bg-primary);
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.18s;
    white-space: nowrap;
}

/* "All" button spans full width */
.diff-btn[data-value="all"] {
    grid-column: 1 / -1;
}

.diff-btn:hover {
    border-color: var(--text-muted);
    color: var(--text-primary);
    background: var(--interactive-hover);
}

.diff-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    flex-shrink: 0;
}

/* Easy */
.diff-btn.diff-easy { border-color: #22c55e33; }
.diff-btn.diff-easy .diff-dot { background: #22c55e; box-shadow: 0 0 0 3px #22c55e22; }
.diff-btn.diff-easy:hover { border-color: #22c55e; background: #f0fdf4; color: #166534; }
.dark-mode .diff-btn.diff-easy:hover { background: rgba(34,197,94,0.08); color: #4ade80; }
.diff-btn.diff-easy.active {
    background: linear-gradient(135deg, #22c55e, #16a34a);
    color: #fff;
    border-color: transparent;
    box-shadow: 0 2px 8px rgba(34,197,94,0.35);
    font-weight: 600;
}
.diff-btn.diff-easy.active .diff-dot { background: rgba(255,255,255,0.7); box-shadow: none; }

/* Medium */
.diff-btn.diff-medium { border-color: #f59e0b33; }
.diff-btn.diff-medium .diff-dot { background: #f59e0b; box-shadow: 0 0 0 3px #f59e0b22; }
.diff-btn.diff-medium:hover { border-color: #f59e0b; background: #fffbeb; color: #854d0e; }
.dark-mode .diff-btn.diff-medium:hover { background: rgba(245,158,11,0.08); color: #fbbf24; }
.diff-btn.diff-medium.active {
    background: linear-gradient(135deg, #f59e0b, #d97706);
    color: #fff;
    border-color: transparent;
    box-shadow: 0 2px 8px rgba(245,158,11,0.35);
    font-weight: 600;
}
.diff-btn.diff-medium.active .diff-dot { background: rgba(255,255,255,0.7); box-shadow: none; }

/* Hard */
.diff-btn.diff-hard { border-color: #f9731633; }
.diff-btn.diff-hard .diff-dot { background: #f97316; box-shadow: 0 0 0 3px #f9731622; }
.diff-btn.diff-hard:hover { border-color: #f97316; background: #fff7ed; color: #9a3412; }
.dark-mode .diff-btn.diff-hard:hover { background: rgba(249,115,22,0.08); color: #fb923c; }
.diff-btn.diff-hard.active {
    background: linear-gradient(135deg, #f97316, #ea580c);
    color: #fff;
    border-color: transparent;
    box-shadow: 0 2px 8px rgba(249,115,22,0.35);
    font-weight: 600;
}
.diff-btn.diff-hard.active .diff-dot { background: rgba(255,255,255,0.7); box-shadow: none; }

/* Very Hard */
.diff-btn.diff-vhard { border-color: #ef444433; }
.diff-btn.diff-vhard .diff-dot { background: #ef4444; box-shadow: 0 0 0 3px #ef444422; }
.diff-btn.diff-vhard:hover { border-color: #ef4444; background: #fef2f2; color: #991b1b; }
.dark-mode .diff-btn.diff-vhard:hover { background: rgba(239,68,68,0.08); color: #f87171; }
.diff-btn.diff-vhard.active {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    color: #fff;
    border-color: transparent;
    box-shadow: 0 2px 8px rgba(239,68,68,0.35);
    font-weight: 600;
}
.diff-btn.diff-vhard.active .diff-dot { background: rgba(255,255,255,0.7); box-shadow: none; }

/* "All" active */
.diff-btn[data-value="all"].active {
    background: var(--accent-primary);
    color: var(--bg-primary);
    border-color: transparent;
    font-weight: 600;
}

.filter-year-row {
    display: flex;
    align-items: center;
    gap: 8px;
}

.filter-year {
    width: 0;
    flex: 1;
    text-align: center;
}

.filter-year-sep {
    color: var(--text-secondary);
    flex-shrink: 0;
}

.filter-reset-btn {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 7px;
    padding: 8px 14px;
    background: none;
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}

.filter-reset-btn:hover {
    background: var(--interactive-hover);
    color: var(--text-primary);
}

/* ── Results area ─────────────────────────────── */
.archive-results {
    min-width: 0;
}

.archive-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
    gap: 12px;
    flex-wrap: wrap;
}

.archive-count {
    font-size: 14px;
    color: var(--text-secondary);
    font-weight: 500;
}

.archive-toolbar-right {
    display: flex;
    align-items: center;
    gap: 10px;
}

.archive-sort-select {
    padding: 7px 12px;
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 14px;
    cursor: pointer;
    outline: none;
    font-family: inherit;
}

.archive-filter-toggle {
    display: none;
    align-items: center;
    gap: 6px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    padding: 7px 13px;
    color: var(--text-primary);
    cursor: pointer;
    font-size: 14px;
    font-family: inherit;
    transition: background 0.2s;
}

.archive-filter-toggle:hover {
    background: var(--interactive-hover);
}

/* Active filter tags */
.active-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 16px;
}

.active-filter-tag {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 4px 10px;
    background: var(--bg-accent);
    border: 1px solid var(--border-secondary);
    border-radius: 20px;
    font-size: 12px;
    color: var(--text-primary);
    font-weight: 500;
}

.active-filter-tag button {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0;
    line-height: 1;
    font-size: 13px;
    transition: color 0.15s;
}

.active-filter-tag button:hover { color: var(--text-primary); }

/* ── Problem grid ─────────────────────────────── */
.archive-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 16px;
}

.archive-loading,
.archive-empty {
    grid-column: 1 / -1;
    text-align: center;
    padding: 64px 20px;
    color: var(--text-secondary);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    font-size: 15px;
}

.archive-loading i { font-size: 28px; color: var(--text-muted); }
.archive-empty i { font-size: 40px; color: var(--border-primary); }
.archive-empty h3 { font-size: 17px; color: var(--text-primary); margin: 0; }
.archive-empty p { font-size: 14px; margin: 0; }

/* ── Problem card ─────────────────────────────── */
.problem-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-primary);
    border-radius: 12px;
    padding: 18px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    transition: box-shadow 0.2s, transform 0.2s, border-color 0.2s;
}

.problem-card:hover {
    box-shadow: 0 6px 20px var(--shadow-medium);
    transform: translateY(-2px);
    border-color: var(--text-muted);
}

.problem-card.is-olympiad {
    border-left: 3px solid #fbbf24;
}

/* Staff action buttons on cards */
.problem-card-staff-actions {
    display: flex;
    gap: 4px;
    flex-shrink: 0;
    margin-left: auto;
}

.card-staff-btn {
    width: 28px;
    height: 28px;
    border: 1px solid var(--border-primary);
    border-radius: 6px;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    transition: all 0.15s;
    flex-shrink: 0;
}

.card-edit-btn:hover {
    background: #eff6ff;
    border-color: #3b82f6;
    color: #3b82f6;
}

.card-delete-btn:hover {
    background: #fef2f2;
    border-color: #ef4444;
    color: #ef4444;
}

.dark-mode .card-edit-btn:hover {
    background: rgba(59,130,246,0.12);
    border-color: #3b82f6;
    color: #60a5fa;
}

.dark-mode .card-delete-btn:hover {
    background: rgba(239,68,68,0.12);
    border-color: #ef4444;
    color: #f87171;
}

.problem-card-top {
    display: flex;
    align-items: flex-start;
    gap: 8px;
}

.problem-card-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
}

.problem-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 3px 9px;
    border-radius: 12px;
    font-size: 11px;
    font-weight: 600;
    white-space: nowrap;
}

.badge-subject {
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border: 1px solid var(--border-primary);
}

.badge-olympiad {
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    color: #92400e;
    border: 1px solid #fcd34d;
}

.dark-mode .badge-olympiad {
    background: rgba(251,191,36,0.15);
    color: #fbbf24;
    border-color: rgba(251,191,36,0.3);
}

.badge-diff-easy   { background: #dcfce7; color: #166534; border: 1px solid #86efac; }
.badge-diff-medium { background: #fef9c3; color: #854d0e; border: 1px solid #fde047; }
.badge-diff-hard   { background: #ffedd5; color: #9a3412; border: 1px solid #fdba74; }
.badge-diff-vhard  { background: #fee2e2; color: #991b1b; border: 1px solid #fca5a5; }

.dark-mode .badge-diff-easy   { background: rgba(34,197,94,0.15);  color: #4ade80; border-color: rgba(34,197,94,0.3); }
.dark-mode .badge-diff-medium { background: rgba(245,158,11,0.15); color: #fbbf24; border-color: rgba(245,158,11,0.3); }
.dark-mode .badge-diff-hard   { background: rgba(249,115,22,0.15); color: #fb923c; border-color: rgba(249,115,22,0.3); }
.dark-mode .badge-diff-vhard  { background: rgba(239,68,68,0.15);  color: #f87171; border-color: rgba(239,68,68,0.3); }

.problem-card-title {
    font-size: 15px;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.4;
    margin: 0;
}

.problem-card-desc {
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.5;
    margin: 0;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.problem-card-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}

.problem-meta-item {
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 12px;
    color: var(--text-secondary);
}

.problem-meta-item i { font-size: 11px; color: var(--text-muted); }

.problem-card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 10px;
    border-top: 1px solid var(--border-primary);
    margin-top: auto;
}

.problem-card-lang {
    display: flex;
    align-items: center;
    gap: 5px;
    font-size: 12px;
    color: var(--text-secondary);
}

.problem-card-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 12px;
    font-weight: 600;
    color: var(--accent-primary);
    text-decoration: none;
    transition: gap 0.15s;
}

.problem-card:hover .problem-card-link { gap: 9px; }

.problem-card-link-disabled {
    font-size: 12px;
    color: var(--text-muted);
}

/* ── Pagination ───────────────────────────────── */
.archive-pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 6px;
    margin-top: 32px;
    flex-wrap: wrap;
}

.page-btn {
    min-width: 36px;
    height: 36px;
    padding: 0 10px;
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.18s;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: inherit;
}

.page-btn:hover:not(:disabled) {
    background: var(--interactive-hover);
    border-color: var(--text-muted);
}

.page-btn.active {
    background: var(--accent-primary);
    color: var(--bg-primary);
    border-color: var(--accent-primary);
    font-weight: 700;
}

.page-btn:disabled { opacity: 0.4; cursor: not-allowed; }
.page-ellipsis { color: var(--text-secondary); padding: 0 4px; font-size: 14px; }

/* ── Upload Modal ─────────────────────────────── */
.archive-modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.55);
    backdrop-filter: blur(3px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    padding: 20px;
}

.archive-modal {
    background: var(--bg-primary);
    border: 1px solid var(--border-primary);
    border-radius: 16px;
    width: 100%;
    max-width: 560px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    box-shadow: 0 20px 60px rgba(0,0,0,0.2);
    overflow: hidden;
}

.archive-modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px 18px;
    border-bottom: 1px solid var(--border-primary);
}

.archive-modal-header h3 {
    font-size: 17px;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
    display: flex;
    align-items: center;
    gap: 10px;
}

.archive-modal-header h3 i { color: var(--text-secondary); }

.archive-modal-close {
    background: none;
    border: none;
    font-size: 22px;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 2px 6px;
    line-height: 1;
    border-radius: 6px;
    transition: background 0.15s;
}

.archive-modal-close:hover { background: var(--interactive-hover); color: var(--text-primary); }

.archive-modal-body {
    padding: 20px 24px;
    overflow-y: auto;
    flex: 1;
}

.upload-form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
}

.upload-form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.upload-form-group label {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-primary);
}

.upload-hint {
    font-size: 11px;
    font-weight: 400;
    color: var(--text-secondary);
}

.req { color: #ef4444; }

.upload-span-2 { grid-column: 1 / -1; }

.upload-input {
    padding: 9px 12px;
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 14px;
    font-family: inherit;
    outline: none;
    transition: border-color 0.2s;
    width: 100%;
    box-sizing: border-box;
}

.upload-input:focus { border-color: var(--accent-primary); }
.upload-textarea { resize: vertical; min-height: 64px; }

.upload-checkbox-label {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    font-size: 14px;
    color: var(--text-primary);
    font-weight: 500;
}

.upload-checkbox-label input[type="checkbox"] {
    width: 16px;
    height: 16px;
    cursor: pointer;
}

.upload-olympiad-fields {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    padding: 14px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-primary);
    border-radius: 10px;
}

.upload-error {
    margin-top: 12px;
    padding: 10px 14px;
    background: #fee2e2;
    border: 1px solid #fca5a5;
    border-radius: 8px;
    color: #991b1b;
    font-size: 13px;
}

.dark-mode .upload-error {
    background: rgba(239,68,68,0.12);
    border-color: rgba(239,68,68,0.3);
    color: #f87171;
}

.archive-modal-footer {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    gap: 10px;
    padding: 16px 24px;
    border-top: 1px solid var(--border-primary);
    background: var(--bg-secondary);
}

.upload-cancel-btn {
    padding: 9px 20px;
    border: 1px solid var(--border-primary);
    border-radius: 8px;
    background: none;
    color: var(--text-primary);
    font-size: 14px;
    cursor: pointer;
    transition: background 0.15s;
    font-family: inherit;
}

.upload-cancel-btn:hover { background: var(--interactive-hover); }

.upload-submit-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 9px 22px;
    border: none;
    border-radius: 8px;
    background: var(--accent-primary);
    color: var(--bg-primary);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.15s;
    font-family: inherit;
}

.upload-submit-btn:hover { opacity: 0.85; }
.upload-submit-btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* ── Responsive ───────────────────────────────── */
@media (max-width: 960px) {
    .archive-layout {
        grid-template-columns: 1fr;
    }

    .archive-filters {
        position: static;
        display: none;
    }

    .archive-filters.open {
        display: block;
    }

    .archive-filter-toggle {
        display: flex;
    }
}

@media (max-width: 600px) {
    .archive-header { flex-direction: column; }
    .archive-header-actions { width: 100%; justify-content: space-between; }
    .archive-stats-row { flex: 1; }
    .archive-stat { flex: 1; min-width: 0; padding: 10px; }
    .archive-grid { grid-template-columns: 1fr; }
    .upload-form-grid { grid-template-columns: 1fr; }
    .upload-olympiad-fields { grid-template-columns: 1fr; }
}