/*
 * KST UI foundation · utilitarian modern-minimal · calm institutional
 * Anchor #18324f · Workbench / Focused Task Surface / Long Document
 * This file is intentionally loaded last so the legacy layouts can stay intact.
 */

:root {
    color-scheme: light;
    --ui-primary: #2563eb;
    --ui-primary-hover: #1d4ed8;
    --ui-primary-active: #1e40af;
    --ui-header: #18324f;
    --ui-canvas: #f5f7fa;
    --ui-surface: #ffffff;
    --ui-surface-subtle: #f8fafc;
    --ui-text: #172033;
    --ui-text-muted: #667085;
    --ui-border: #dfe4ea;
    --ui-border-strong: #8793a3;
    --ui-success: #15803d;
    --ui-warning: #b45309;
    --ui-danger: #dc2626;
    --ui-focus: rgba(37, 99, 235, 0.24);
    --ui-radius-sm: 8px;
    --ui-radius-md: 12px;
    --ui-radius-lg: 16px;
    --ui-shadow-sm: none;
    --ui-shadow-md: 0 8px 24px rgba(16, 24, 40, 0.08);
    --ui-font: "Segoe UI Variable", "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
    --ui-space-1: 4px;
    --ui-space-2: 8px;
    --ui-space-3: 12px;
    --ui-space-4: 16px;
    --ui-space-6: 24px;
    --ui-space-8: 32px;
    --ui-duration-fast: 160ms;
    --ui-ease-out: cubic-bezier(0.16, 1, 0.3, 1);

    /* Keep the legacy components on the same palette. */
    --primary: var(--ui-primary);
    --primary-light: #3b82f6;
    --accent: var(--ui-primary);
    --accent-hover: var(--ui-primary-hover);
    --bg: var(--ui-canvas);
    --card: var(--ui-surface);
    --text: var(--ui-text);
    --text-light: var(--ui-text-muted);
    --border: var(--ui-border);
    --shadow: var(--ui-shadow-sm);
    --shadow-lg: var(--ui-shadow-md);
}

[data-theme="dark"] {
    color-scheme: dark;
    --ui-primary: #60a5fa;
    --ui-primary-hover: #93c5fd;
    --ui-primary-active: #bfdbfe;
    --ui-canvas: #10141d;
    --ui-surface: #181e29;
    --ui-surface-subtle: #202735;
    --ui-text: #f3f4f6;
    --ui-text-muted: #aab3c2;
    --ui-border: #343d4d;
    --ui-border-strong: #68768a;
    --ui-success: #4ade80;
    --ui-warning: #fbbf24;
    --ui-danger: #f87171;
    --ui-focus: rgba(96, 165, 250, 0.32);
    --ui-shadow-sm: none;
    --ui-shadow-md: 0 10px 28px rgba(0, 0, 0, 0.28);

    --primary: var(--ui-primary);
    --primary-light: var(--ui-primary-hover);
    --accent: var(--ui-primary);
    --accent-hover: var(--ui-primary-hover);
    --bg: var(--ui-canvas);
    --card: var(--ui-surface);
    --text: var(--ui-text);
    --text-light: var(--ui-text-muted);
    --border: var(--ui-border);
    --shadow: var(--ui-shadow-sm);
    --shadow-lg: var(--ui-shadow-md);
}

html,
body,
button,
input,
select,
textarea {
    font-family: var(--ui-font);
}

html,
body {
    max-width: 100%;
    overflow-x: clip;
}

body {
    background-color: var(--ui-canvas);
    color: var(--ui-text);
    text-rendering: optimizeLegibility;
}

.kst-icon {
    display: inline-block;
    width: 1.125em;
    height: 1.125em;
    flex: 0 0 auto;
    fill: none;
    stroke: currentColor;
    stroke-width: 1.8;
    stroke-linecap: round;
    stroke-linejoin: round;
    vertical-align: -0.18em;
}

.input-icon .kst-icon,
.photo-placeholder .kst-icon,
.screenshot-warning .kst-icon {
    width: 1em;
    height: 1em;
}

.screenshot-warning {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--ui-space-3);
    padding-inline: var(--ui-space-4);
}

.btn-icon-edit::before,
.btn-icon-delete::before {
    content: none;
}

/* Legacy text inside the small theme thumb overlapped the thumb itself. */
#screen-admin .theme-toggle-circle::before {
    content: none !important;
}

/* Flat page canvases. */
.login-page,
.exam-page,
.srez-page,
.test-page,
#screen-admin,
.admin-content {
    background-color: var(--ui-canvas);
    background-image: none;
}

/* Shared fields, scoped to application roots to avoid utility controls. */
:where(.login-page, .container, .exam-page, .srez-page, .test-page, #screen-admin)
    :where(input:not([type="checkbox"]):not([type="radio"]):not([type="file"]):not([type="range"]), select, textarea) {
    border: 1px solid var(--ui-border);
    border-radius: var(--ui-radius-sm);
    background-color: var(--ui-surface);
    background-image: none;
    color: var(--ui-text);
    box-shadow: none;
    transition: color 160ms ease, background-color 160ms ease, border-color 160ms ease;
}

:where(.login-page, .container, .exam-page, .srez-page, .test-page, #screen-admin)
    :where(input:not([type="checkbox"]):not([type="radio"]):not([type="file"]):not([type="range"]), select, textarea)::placeholder {
    color: var(--ui-text-muted);
    opacity: 0.78;
}

:where(.login-page, .container, .exam-page, .srez-page, .test-page, #screen-admin)
    :where(input:not([type="checkbox"]):not([type="radio"]):not([type="file"]):not([type="range"]), select, textarea):focus {
    outline: none;
    border-color: var(--ui-primary);
    box-shadow: 0 0 0 3px var(--ui-focus);
}

/* Keyboard focus is visible without changing mouse/touch states. */
:where(button, [role="button"], a, input, select, textarea):focus-visible {
    outline: 3px solid var(--ui-focus);
    outline-offset: 2px;
}

/* Shared button geometry. Anti-cheat and watermark controls are not included. */
:where(.btn, .btn-small, .btn-sm, .btn-icon, .login-btn, .submit-btn, .start-btn, .modal-close, .btn-close) {
    border-radius: var(--ui-radius-sm);
    background-image: none;
    box-shadow: none;
    font-weight: 600;
    transition: background-color 160ms ease, border-color 160ms ease, color 160ms ease, opacity 160ms ease;
}

:where(.btn-primary, .login-btn, .submit-btn, .start-btn) {
    background-color: var(--ui-primary);
    color: #ffffff;
    border-color: var(--ui-primary);
}

:where(.btn-primary, .login-btn, .submit-btn, .start-btn):hover:not(:disabled) {
    background-color: var(--ui-primary-hover);
    border-color: var(--ui-primary-hover);
    color: #ffffff;
    transform: none;
    box-shadow: none;
}

:where(.btn-primary, .login-btn, .submit-btn, .start-btn):active:not(:disabled) {
    background-color: var(--ui-primary-active);
}

:where(.btn-secondary, .btn-outline) {
    background-color: var(--ui-surface);
    color: var(--ui-text);
    border: 1px solid var(--ui-border-strong);
}

:where(.btn-secondary, .btn-outline):hover:not(:disabled) {
    background-color: var(--ui-surface-subtle);
    border-color: var(--ui-border-strong);
    transform: none;
    box-shadow: none;
}

:where(.btn-danger, .btn-danger-outline) {
    box-shadow: none;
}

:where(button, .btn):disabled {
    opacity: 0.55;
}

/* Public entry pages. */
.login-card,
.main-card,
.exam-card,
.srez-card,
.exam-page .confirm-card,
.srez-page .confirm-card,
.exam-page .error-card,
.srez-page .error-card {
    background-color: var(--ui-surface);
    background-image: none;
    border: 1px solid var(--ui-border);
    border-radius: var(--ui-radius-lg);
    box-shadow: none;
}

.login-logo,
.main-card .logo,
.exam-card .logo-img,
.srez-card .logo-img {
    border-radius: var(--ui-radius-md);
    box-shadow: none;
}

:where(.login-header, .main-card, .exam-card, .srez-card, .confirm-card, .error-card) :where(h1, h2, h3),
.modal-title {
    color: var(--ui-text);
    letter-spacing: -0.015em;
}

:where(.login-header, .main-card, .exam-card, .srez-card, .confirm-card, .error-card) :where(p, .subtitle, .code-hint),
.footer,
.modal-body p,
.modal-body li {
    color: var(--ui-text-muted);
}

.info-card,
.confirm-header,
.test-info-row {
    background-color: var(--ui-surface-subtle);
    background-image: none;
    border: 1px solid var(--ui-border);
    border-radius: var(--ui-radius-md);
    box-shadow: none;
}

.info-card:hover {
    background-color: var(--ui-surface);
    border-color: var(--ui-primary);
    transform: none;
}

.info-card-title,
.student-name,
.test-info-value {
    color: var(--ui-text);
}

.student-group,
.test-info-label {
    color: var(--ui-text-muted);
}

.student-photo {
    border-color: var(--ui-surface);
    box-shadow: none;
}

.login-form label,
.login-footer a {
    color: var(--ui-text);
}

.login-footer p,
.exam-page .loading-screen,
.srez-page .loading-screen {
    color: var(--ui-text-muted);
}

/* Modal surfaces only; positioning, visibility and stacking remain legacy-owned. */
.modal-overlay .modal,
.modal-content,
.system-modal {
    background-color: var(--ui-surface);
    background-image: none;
    color: var(--ui-text);
    border: 1px solid var(--ui-border);
    border-radius: var(--ui-radius-lg);
    box-shadow: var(--ui-shadow-md);
}

.modal-overlay .modal-header,
.modal-overlay .modal-footer,
.modal-content > .modal-header,
.modal-content > .modal-footer {
    background-color: var(--ui-surface);
    background-image: none;
    border-color: var(--ui-border);
}

.modal-overlay .modal-close,
.btn-close {
    background-color: var(--ui-surface-subtle);
    color: var(--ui-text-muted);
}

.modal-overlay .modal-close:hover,
.btn-close:hover {
    background-color: #fee2e2;
    color: var(--ui-danger);
}

[data-theme="dark"] .modal-overlay .modal-close:hover,
[data-theme="dark"] .btn-close:hover {
    background-color: #4b2228;
}

/* Administration shell, navigation and content. */
.admin-sticky-header {
    background-color: var(--ui-canvas);
}

.admin-header,
[data-theme="dark"] .admin-header {
    background-color: var(--ui-header);
    background-image: none;
    border: 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.14);
    box-shadow: none;
}

.admin-header-logo {
    border: 1px solid rgba(255, 255, 255, 0.45);
    border-radius: var(--ui-radius-md);
    box-shadow: none;
}

.admin-header :where(.btn-secondary, .btn-help) {
    background-color: rgba(255, 255, 255, 0.1);
    background-image: none;
    border: 1px solid rgba(255, 255, 255, 0.28);
    box-shadow: none;
}

.admin-header :where(.btn-secondary, .btn-help):hover {
    background-color: rgba(255, 255, 255, 0.17);
    border-color: rgba(255, 255, 255, 0.42);
    transform: none;
}

.admin-tabs,
[data-theme="dark"] .admin-tabs {
    background-color: var(--ui-surface);
    background-image: none;
    border-bottom: 1px solid var(--ui-border);
    box-shadow: none;
    flex-wrap: nowrap;
    overflow-x: auto;
    overflow-y: hidden;
    scrollbar-width: thin;
    overscroll-behavior-inline: contain;
}

.admin-tab {
    flex: 0 0 auto;
    white-space: nowrap;
    border-bottom-width: 2px;
    color: var(--ui-text-muted);
}

.admin-tab:hover,
[data-theme="dark"] .admin-tab:hover {
    background-color: var(--ui-surface-subtle);
    color: var(--ui-text);
}

.admin-tab.active,
[data-theme="dark"] .admin-tab.active {
    background-color: var(--ui-surface);
    color: var(--ui-primary);
    border-bottom-color: var(--ui-primary);
}

.admin-content {
    gap: 16px;
}

.admin-section,
[data-theme="dark"] .admin-section {
    background-color: var(--ui-surface);
    background-image: none;
    border: 1px solid var(--ui-border);
    border-radius: var(--ui-radius-md);
    box-shadow: var(--ui-shadow-sm);
}

.section-header,
.admin-section h2 {
    border-bottom-color: var(--ui-border);
}

/* Frequently used admin cards: remove visual noise but preserve their grids. */
#screen-admin :where(
    .discipline-card,
    .topic-card,
    .test-card,
    .profile-card,
    .stat-card,
    .summary-card,
    .user-card-new,
    .setting-row,
    .guide-card,
    .analytics-panel,
    .analytics-kpi-card
) {
    background-color: var(--ui-surface);
    background-image: none;
    border-color: var(--ui-border);
    border-radius: var(--ui-radius-md);
    box-shadow: none;
}

/* Motion is deliberately quiet: controls may change colour, not jump or grow. */
:where(
    .btn-primary:hover:not(:disabled),
    .btn-role:hover,
    .answer-option-image:hover,
    .match-left-image:hover,
    .match-item-image:hover,
    .nav-question-btn.current,
    .test-short-code:hover,
    .btn-icon:hover,
    .user-stat-card:hover,
    .profile-avatar.clickable:hover,
    .tour-dot,
    .btn-help:hover,
    .summary-card:hover,
    .exam-link:hover,
    .btn-accent:hover,
    .system-modal-footer .btn-primary:hover,
    .image-upload-area.dragover,
    .image-preview-actions button:hover,
    .image-zoom-close:hover,
    .help-feature:hover,
    .interactive-element:hover,
    .interactive-card:hover,
    .group-card:hover,
    .student-photo:hover,
    .crop-resize-handle:hover,
    .role-card:hover .role-card-content,
    .modal-content .form-actions .btn-primary:hover,
    .test-type-card:hover .test-type-card-content,
    .btn-danger:hover,
    .crop-corner:hover,
    .photo-action-btn:hover,
    .variant-card:hover,
    .assign-variant-btn:hover,
    .folder-card:hover,
    .color-option:hover,
    .group-chip:hover:not(:disabled)
) {
    transform: none !important;
}

.interactive-card:hover .card-arrow {
    transform: translateY(-50%) !important;
}

:where(.modal-overlay, .modal, .modal-content, .import-tab-content, .tour-card) {
    animation: none !important;
}

/* Result and analytics views stay calm: no staged reveals or hover movement. */
:where(
    .leaderboard-section,
    .leaderboard-entry,
    .leaderboard-entry.current-student,
    .blocker-btn,
    .analytics-section .analytics-report-button
) {
    animation: none !important;
}

:where(
    .leaderboard-entry:hover,
    .blocker-btn:hover,
    .analytics-section .analytics-report-button:hover
) {
    transform: none !important;
    box-shadow: none !important;
}

.modal-close svg,
.btn-close svg {
    width: 18px;
    height: 18px;
    pointer-events: none;
}

/* Discipline cards: high-contrast work objects, not decorative tiles. */
#screen-admin .discipline-card,
[data-theme="dark"] #screen-admin .discipline-card {
    border: 1px solid var(--ui-border-strong);
    border-top: 3px solid var(--ui-primary);
    border-radius: var(--ui-radius-md);
    background: var(--ui-surface);
    box-shadow: none;
}

#screen-admin .discipline-card::before,
#screen-admin .discipline-card::after {
    display: none;
}

#screen-admin .discipline-card-header h3 {
    color: var(--ui-text);
    font-size: 1.02rem;
    font-weight: 750;
    line-height: 1.35;
}

#screen-admin .discipline-direction {
    gap: var(--ui-space-1);
    max-width: 100%;
    padding: 4px 7px;
    color: var(--ui-primary-active);
    background: var(--ui-surface-subtle);
    border: 1px solid var(--ui-border-strong);
    border-radius: 5px;
    font-weight: 600;
}

#screen-admin .discipline-stats {
    background: var(--ui-surface-subtle);
    border-block: 1px solid var(--ui-border);
}

#screen-admin .discipline-stats .stat-item,
[data-theme="dark"] #screen-admin .discipline-stats .stat-item {
    background: var(--ui-surface);
    border: 1px solid var(--ui-border);
    border-radius: var(--ui-radius-sm);
    box-shadow: none;
    transition: border-color var(--ui-duration-fast) ease;
}

#screen-admin .discipline-card:hover .discipline-stats .stat-item {
    transform: none;
    box-shadow: none;
}

#screen-admin .discipline-stats .stat-value {
    color: var(--ui-primary-active);
}

#screen-admin .discipline-stats .stat-label {
    color: var(--ui-text-muted);
    letter-spacing: 0.04em;
}

#screen-admin .discipline-author,
[data-theme="dark"] #screen-admin .discipline-author {
    color: var(--ui-text);
    background: var(--ui-surface);
    border-top: 1px solid var(--ui-border);
}

#screen-admin .discipline-author .author-label,
#screen-admin .entity-created-at {
    color: var(--ui-text-muted);
    opacity: 1;
}

/* The crop mask uses borders for its guide; a decorative radial fill is unnecessary. */
.avatar-crop-overlay {
    background: transparent;
}

#screen-admin :where(
    .discipline-card,
    .topic-card,
    .test-card,
    .user-card-new
):hover {
    transform: none;
    box-shadow: none;
    border-color: var(--ui-border-strong);
}

/* Tables retain their existing column sizing and overflow wrappers. */
#screen-admin table,
.test-page table {
    background-color: var(--ui-surface);
    color: var(--ui-text);
    border-color: var(--ui-border);
}

#screen-admin th,
.test-page th {
    background-color: var(--ui-surface-subtle);
    background-image: none;
    color: var(--ui-text-muted);
    border-color: var(--ui-border);
}

#screen-admin td,
.test-page td {
    border-color: var(--ui-border);
}

#screen-admin tbody tr:hover td,
.test-page tbody tr:hover td {
    background-color: var(--ui-surface-subtle);
}

/* Test flow: update presentation without touching security overlays or watermarks. */
.test-page :where(.password-card, .instructions-card, .error-card, .question-card, .result-card, .test-header, .test-body, .test-footer) {
    background-color: var(--ui-surface);
    background-image: none;
    border-color: var(--ui-border);
    border-radius: var(--ui-radius-md);
    box-shadow: none;
}

.test-page :where(.test-param, .warning-box, .answer-option, .short-answer-container) {
    background-image: none;
    border-radius: var(--ui-radius-sm);
}

[data-theme="dark"] :where(.login-page, .exam-page, .srez-page, .test-page) {
    background-color: var(--ui-canvas);
}

[data-theme="dark"] :where(.login-card, .main-card, .exam-card, .srez-card, .exam-page .confirm-card, .srez-page .confirm-card, .exam-page .error-card, .srez-page .error-card) {
    background-color: var(--ui-surface);
    border-color: var(--ui-border);
}

[data-theme="dark"] :where(.info-card, .confirm-header, .test-info-row) {
    background-color: var(--ui-surface-subtle);
    border-color: var(--ui-border);
}

@media (max-width: 768px) {
    .admin-tabs,
    [data-theme="dark"] .admin-tabs {
        padding: 0 12px;
        gap: 0;
        flex-wrap: nowrap;
    }

    .admin-tab {
        flex: 0 0 auto;
        min-width: auto;
        padding: 12px 14px;
    }

    .admin-content,
    .admin-tab-content {
        padding-left: 16px;
        padding-right: 16px;
    }

    .admin-section {
        padding: 20px 16px;
    }
}

@media (max-width: 480px) {
    .login-card,
    .main-card,
    .exam-card,
    .srez-card,
    .exam-page .confirm-card,
    .srez-page .confirm-card,
    .exam-page .error-card,
    .srez-page .error-card {
        border-radius: var(--ui-radius-md);
        box-shadow: none;
    }

    .admin-tab {
        min-width: auto;
        padding: 11px 12px;
        font-size: 13px;
    }
}

@media (pointer: coarse) {
    :where(button, .btn, [role="button"], .admin-tab, input, select) {
        min-height: 44px;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    :where(button, [role="button"], a, input, select, textarea, .modal, .modal-content, .info-card, .admin-tab) {
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}