:root {
    --dark-bg: #f6f2ec;
    --darker-bg: #ffffff;
    --card-bg: #ffffff;
    --border-color: rgba(19, 32, 62, 0.14);
    --accent-green: #1f7a8c;
    --accent-green-dark: #165865;
    --accent-blue: #1b2a4e;
    --accent-purple: #e07a5f;
    --text-primary: #1a1f2b;
    --text-secondary: #5b6375;
    --metallic-1: #f0c987;
    --metallic-2: #9aa3b2;
    --neon-shadow: 0 10px 30px rgba(31, 122, 140, 0.12);
    --neon-glow: 0 18px 40px rgba(31, 122, 140, 0.18);
    --danger: #c84747;
    --warning: #d8a84a;
    --info: #4b7caa;
    --success: #2d9a6a;
    --font-body: "IBM Plex Sans", sans-serif;
    --font-heading: "Cormorant Garamond", serif;
    --font-mono: "IBM Plex Mono", monospace;

    --bg-page: #f6f2ec;
    --bg-surface: #ffffff;
    --bg-card: #ffffff;
    --bg-header: rgba(246, 242, 236, 0.9);
    --accent-contrast: #ffffff;
    --shadow-soft: 0 10px 20px rgba(19, 32, 62, 0.08);
    --btn-primary-bg: linear-gradient(135deg, #0f172a, #155e75);
    --btn-primary-bg-hover: linear-gradient(135deg, #020617, #0f766e);
    --btn-primary-text: #ffffff;
    --btn-primary-shadow: 0 14px 30px rgba(15, 23, 42, 0.18);
    --btn-primary-shadow-hover: 0 18px 34px rgba(15, 23, 42, 0.24);
    --btn-primary-shadow-active: inset 0 1px 0 rgba(255, 255, 255, 0.08), 0 10px 22px rgba(15, 23, 42, 0.2);
    --btn-secondary-bg: #ffffff;
    --btn-secondary-bg-hover: #f8fafc;
    --btn-secondary-text: #0f172a;
    --btn-secondary-border: rgba(15, 23, 42, 0.14);
}
[data-theme="dark"] {
    --bg-page: #0f1720;
    --bg-surface: #131d2a;
    --bg-card: #182433;
    --bg-header: rgba(15, 23, 32, 0.92);
    --dark-bg: #0f1720;
    --darker-bg: #131d2a;
    --card-bg: #182433;
    --border-color: rgba(165, 184, 209, 0.22);
    --accent-green: #27a6b2;
    --accent-green-dark: #1e828c;
    --accent-blue: #d7e4ff;
    --accent-purple: #f0987f;
    --text-primary: #e7edf5;
    --text-secondary: #a6b5c8;
    --metallic-1: #ffd08f;
    --metallic-2: #8a99b3;
    --neon-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
    --neon-glow: 0 18px 40px rgba(0, 0, 0, 0.5);
    --danger: #ff7474;
    --warning: #f2ca74;
    --info: #8bb5ff;
    --success: #62d49f;
    --btn-primary-bg: linear-gradient(135deg, #2563eb, #3b82f6);
    --btn-primary-bg-hover: linear-gradient(135deg, #3b82f6, #60a5fa);
    --btn-primary-text: #f8fafc;
    --btn-primary-shadow: 0 14px 28px rgba(37, 99, 235, 0.34);
    --btn-primary-shadow-hover: 0 18px 34px rgba(59, 130, 246, 0.42);
    --btn-primary-shadow-active: inset 0 1px 0 rgba(255, 255, 255, 0.08), 0 10px 22px rgba(37, 99, 235, 0.28);
    --btn-secondary-bg: #182433;
    --btn-secondary-bg-hover: #1f2d3f;
    --btn-secondary-text: #e7edf5;
    --btn-secondary-border: rgba(165, 184, 209, 0.2);
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.drag-handle,
.section-card,
.lesson-item {
    user-select: none;
    -webkit-user-select: none;
    -ms-user-select: none;
}

body {
    font-family: var(--font-body);
    background: var(--bg-page);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    color: var(--accent-blue);
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    background:
        radial-gradient(circle at 15% 20%, rgba(31, 122, 140, 0.12), transparent 45%),
        radial-gradient(circle at 85% 10%, rgba(224, 122, 95, 0.12), transparent 40%),
        radial-gradient(circle at 60% 80%, rgba(27, 42, 78, 0.12), transparent 50%);
    z-index: -2;
}

body::after {
    content: "";
    position: fixed;
    inset: 0;
    background-image: linear-gradient(120deg, rgba(255, 255, 255, 0.6), rgba(255, 255, 255, 0.1));
    opacity: 0.25;
    z-index: -3;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

main {
    padding: 48px 0 80px;
    min-height: calc(100vh - 260px);
}

.section-title {
    font-family: var(--font-heading);
    font-size: 2.2rem;
    margin-bottom: 24px;
    color: var(--accent-blue);
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.flash-messages {
    margin: 20px 0 10px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.flash-message {
    padding: 12px 16px;
    border-radius: 12px;
    border: 1px solid rgba(27, 42, 78, 0.15);
    background: var(--bg-card);
    color: var(--text-primary);
    box-shadow: 0 10px 20px rgba(19, 32, 62, 0.08);
}

.flash-message.success {
    border-color: rgba(45, 154, 106, 0.4);
    background: rgba(45, 154, 106, 0.08);
    color: #1c6f4d;
}

.flash-message.error {
    border-color: rgba(200, 71, 71, 0.35);
    background: rgba(200, 71, 71, 0.08);
    color: #9f2a2a;
}

.flash-message.warning {
    border-color: rgba(216, 168, 74, 0.4);
    background: rgba(216, 168, 74, 0.08);
    color: #7d5a14;
}

.pch-toast-root {
    position: fixed;
    top: 88px;
    right: 16px;
    z-index: 12000;
    display: flex;
    flex-direction: column;
    gap: 10px;
    max-width: min(92vw, 380px);
}

.pch-toast {
    border-radius: 12px;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    color: var(--text-primary);
    padding: 12px 14px;
    box-shadow: 0 10px 24px rgba(19, 32, 62, 0.18);
    transform: translateY(-8px);
    opacity: 0;
    transition: opacity 0.2s ease, transform 0.2s ease;
}

.pch-toast.is-visible {
    opacity: 1;
    transform: translateY(0);
}

.pch-toast-success {
    border-color: rgba(45, 154, 106, 0.45);
    background: rgba(45, 154, 106, 0.12);
}

.pch-toast-error {
    border-color: rgba(200, 71, 71, 0.45);
    background: rgba(200, 71, 71, 0.12);
}

.pch-toast-warning {
    border-color: rgba(216, 168, 74, 0.45);
    background: rgba(216, 168, 74, 0.14);
}

.pch-dialog-root {
    position: fixed;
    inset: 0;
    z-index: 13000;
    display: none;
}

.pch-dialog-root.is-open {
    display: block;
}

.pch-dialog-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(7, 14, 28, 0.74);
    backdrop-filter: blur(3px);
}

.pch-dialog {
    position: relative;
    width: min(94vw, 560px);
    margin: 12vh auto 0;
    padding: 24px;
    border-radius: 16px;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    box-shadow: 0 20px 48px rgba(6, 12, 24, 0.35);
}

.pch-dialog-title {
    margin: 0 0 10px;
}

.pch-dialog-message {
    margin: 0 0 20px;
    color: var(--text-secondary);
}

.pch-dialog-actions {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.pch-dialog-actions .btn-danger {
    background: #c84747;
    color: #fff;
    border: 1px solid #c84747;
}

.pch-dialog-actions .btn-danger:hover {
    background: #a73a3a;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg-header);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 12px 30px rgba(19, 32, 62, 0.08);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    padding: 18px 0;
    flex-wrap: wrap;
}

.brand {
    display: flex;
    align-items: center;
    gap: 16px;
    text-decoration: none;
    color: inherit;
}

.brand-mark {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    border-radius: 14px;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-green));
    color: var(--accent-contrast);
    font-weight: 700;
    letter-spacing: 1px;
    font-size: 1rem;
    box-shadow: var(--neon-shadow);
}

.brand-text {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.brand-title {
    font-family: var(--font-heading);
    font-size: 1.6rem;
    font-weight: 700;
    letter-spacing: 0.5px;
}

.brand-subtitle {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.site-nav {
    display: flex;
    align-items: center;
    gap: 18px;
    flex-wrap: wrap;
}

.nav-link {
    position: relative;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 6px 0;
    transition: color 0.2s ease;
}

.nav-link::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -4px;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-green), var(--accent-purple));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.25s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--accent-blue);
}

.nav-link:hover::after,
.nav-link.active::after {
    transform: scaleX(1);
}

.header-actions {
    display: flex;
    gap: 12px;
    align-items: center;
    flex-wrap: wrap;
}

.btn {
    padding: 10px 20px;
    border-radius: 999px;
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 600;
    border: 1px solid transparent;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    text-shadow: none;
}

.btn-primary {
    background: var(--btn-primary-bg);
    color: var(--btn-primary-text);
    box-shadow: var(--btn-primary-shadow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    background: var(--btn-primary-bg-hover);
    color: var(--btn-primary-text);
    box-shadow: var(--btn-primary-shadow-hover);
}

.btn-primary:active {
    transform: translateY(0);
    box-shadow: var(--btn-primary-shadow-active);
    filter: brightness(0.96);
}

.btn-secondary {
    background: var(--btn-secondary-bg);
    color: var(--btn-secondary-text);
    border-color: var(--btn-secondary-border);
}

.btn-secondary:hover {
    transform: translateY(-2px);
    background: var(--btn-secondary-bg-hover);
    color: var(--btn-secondary-text);
    box-shadow: 0 12px 20px rgba(27, 42, 78, 0.12);
}

.btn-primary,
.btn-primary:visited,
.btn-primary:hover,
.btn-primary:active,
.btn-primary:focus-visible,
.btn-primary * {
    color: var(--btn-primary-text) !important;
}

.btn-secondary,
.btn-secondary:visited,
.btn-secondary:hover,
.btn-secondary:active,
.btn-secondary:focus-visible,
.btn-secondary * {
    color: var(--btn-secondary-text) !important;
}

.btn:focus-visible {
    outline: none;
    box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.88), 0 0 0 6px rgba(15, 23, 42, 0.18);
}

.btn-outline {
    background: transparent;
    color: var(--accent-blue);
    border-color: var(--accent-blue);
}

.btn-outline:hover {
    background: rgba(27, 42, 78, 0.08);
}

.card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 18px;
    padding: 28px;
    box-shadow: 0 20px 40px rgba(19, 32, 62, 0.08);
}

.badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 12px;
    border-radius: 999px;
    background: rgba(31, 122, 140, 0.1);
    color: var(--accent-green-dark);
    font-size: 0.75rem;
    font-weight: 600;
}

.tag {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    border-radius: 999px;
    background: rgba(224, 122, 95, 0.12);
    color: #b24f38;
    font-size: 0.75rem;
    font-weight: 600;
    text-decoration: none;
}

input,
select,
textarea {
    width: 100%;
    padding: 12px 16px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    font-family: var(--font-body);
    font-size: 1rem;
    color: var(--text-primary);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input[type="checkbox"],
input[type="radio"] {
    width: auto;
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: rgba(31, 122, 140, 0.5);
    box-shadow: 0 0 0 3px rgba(31, 122, 140, 0.12);
}

label {
    font-weight: 600;
    color: var(--text-primary);
}

.help-text {
    display: block;
    margin-top: 6px;
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 18px;
}

.table-wrapper {
    background: var(--bg-card);
    border-radius: 16px;
    border: 1px solid var(--border-color);
    box-shadow: 0 20px 40px rgba(19, 32, 62, 0.08);
    overflow: hidden;
}

.table-wrapper table {
    width: 100%;
    border-collapse: collapse;
}

.table-wrapper th,
.table-wrapper td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid rgba(19, 32, 62, 0.08);
}

.table-wrapper th {
    background: rgba(27, 42, 78, 0.06);
    font-weight: 600;
}

.footer {
    background: rgba(27, 42, 78, 0.95);
    color: var(--accent-contrast);
    margin-top: 80px;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 56px 24px 32px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 32px;
}

.footer-section h3,
.footer-section h4 {
    font-family: var(--font-heading);
    margin-bottom: 14px;
}

.footer-section p,
.footer-section a {
    color: rgba(255, 255, 255, 0.78);
    text-decoration: none;
    font-size: 0.95rem;
}

.footer-section ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.footer-section a:hover {
    color: var(--accent-contrast);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.12);
    padding: 18px 24px 26px;
    text-align: center;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
}

code,
pre {
    font-family: var(--font-mono);
}

@media (max-width: 900px) {
    .header-inner {
        flex-direction: column;
        align-items: flex-start;
    }

    .site-nav {
        width: 100%;
        justify-content: flex-start;
        gap: 12px;
    }

    .header-actions {
        width: 100%;
        justify-content: flex-start;
    }

    .brand-subtitle {
        font-size: 0.8rem;
    }
}

@media (max-width: 600px) {
    .brand-mark {
        width: 40px;
        height: 40px;
        font-size: 0.85rem;
    }

    .brand-title {
        font-size: 1.3rem;
    }

    main {
        padding: 32px 0 60px;
    }

    .btn {
        width: 100%;
    }
}

.theme-toggle {
    position: fixed;
    right: 20px;
    bottom: 20px;
    z-index: 1200;
    border: 1px solid var(--border-color);
    border-radius: 999px;
    padding: 10px 14px;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--bg-card);
    color: var(--text-primary);
    box-shadow: var(--shadow-soft);
    cursor: pointer;
}

.btn-sm {
    padding: 7px 12px;
    font-size: 0.85rem;
}

.btn-lg {
    padding: 12px 22px;
    font-size: 1rem;
}
.theme-toggle__icon {
    width: 16px;
    text-align: center;
}

.theme-smooth body,
.theme-smooth .site-header,
.theme-smooth .card,
.theme-smooth .btn,
.theme-smooth .course-card,
.theme-smooth .forum-header,
.theme-smooth .topic-post-card,
.theme-smooth input,
.theme-smooth textarea,
.theme-smooth select,
.theme-smooth .theme-toggle,
.theme-smooth .footer,
.theme-smooth a,
.theme-smooth h1,
.theme-smooth h2,
.theme-smooth h3,
.theme-smooth h4,
.theme-smooth h5,
.theme-smooth h6,
.theme-smooth p,
.theme-smooth span,
.theme-smooth div {
    transition: background-color 0.35s ease, color 0.35s ease, border-color 0.35s ease, box-shadow 0.35s ease;
}

/* Dark-theme hardening: force readable colors for legacy templates with inline styles */
[data-theme="dark"] {
    color-scheme: dark;
}

[data-theme="dark"] body,
[data-theme="dark"] p,
[data-theme="dark"] li,
[data-theme="dark"] span,
[data-theme="dark"] div,
[data-theme="dark"] small,
[data-theme="dark"] strong,
[data-theme="dark"] label {
    color: var(--text-primary);
}

[data-theme="dark"] h1,
[data-theme="dark"] h2,
[data-theme="dark"] h3,
[data-theme="dark"] h4,
[data-theme="dark"] h5,
[data-theme="dark"] h6 {
    color: var(--accent-blue);
}

[data-theme="dark"] a:not(.btn) {
    color: var(--info);
}

[data-theme="dark"] a.btn,
[data-theme="dark"] a.btn-primary,
[data-theme="dark"] a.btn-secondary,
[data-theme="dark"] a.btn-outline {
    color: inherit;
}

[data-theme="dark"] .btn-primary {
    color: var(--accent-contrast) !important;
}

[data-theme="dark"] .btn-primary,
[data-theme="dark"] .btn-primary:visited,
[data-theme="dark"] .btn-primary * {
    color: var(--accent-contrast) !important;
}

[data-theme="dark"] .btn-secondary,
[data-theme="dark"] .btn-secondary:visited,
[data-theme="dark"] .btn-outline,
[data-theme="dark"] .btn-outline:visited {
    color: var(--text-primary) !important;
}

[data-theme="dark"] .btn-secondary,
[data-theme="dark"] .btn-outline {
    color: var(--text-primary);
    border-color: var(--border-color);
    background: var(--bg-card);
}

[data-theme="dark"] .table-wrapper th {
    background: rgba(215, 228, 255, 0.08);
    color: var(--text-primary);
}

[data-theme="dark"] .table-wrapper td {
    color: var(--text-primary);
    border-bottom-color: rgba(165, 184, 209, 0.2);
}

[data-theme="dark"] code,
[data-theme="dark"] pre {
    background: rgba(215, 228, 255, 0.08);
    color: var(--text-primary);
    border-radius: 8px;
}

[data-theme="dark"] .flash-message.success {
    color: #9fe8c8;
}

[data-theme="dark"] .flash-message.error {
    color: #ffb3b3;
}

[data-theme="dark"] .flash-message.warning {
    color: #ffd89a;
}

/* Inline-style overrides from legacy pages */
[data-theme="dark"] [style*="background: #fff"],
[data-theme="dark"] [style*="background:#fff"],
[data-theme="dark"] [style*="background-color: #fff"],
[data-theme="dark"] [style*="background-color:#fff"],
[data-theme="dark"] [style*="background: #ffffff"],
[data-theme="dark"] [style*="background:#ffffff"],
[data-theme="dark"] [style*="background-color: #ffffff"],
[data-theme="dark"] [style*="background-color:#ffffff"],
[data-theme="dark"] [style*="background: white"],
[data-theme="dark"] [style*="background:white"],
[data-theme="dark"] [style*="background-color: white"],
[data-theme="dark"] [style*="background-color:white"] {
    background: var(--bg-card) !important;
}

[data-theme="dark"] [style*="color: #000"],
[data-theme="dark"] [style*="color:#000"],
[data-theme="dark"] [style*="color: #333"],
[data-theme="dark"] [style*="color:#333"],
[data-theme="dark"] [style*="color: #666"],
[data-theme="dark"] [style*="color:#666"],
[data-theme="dark"] [style*="color: #1a1a1a"],
[data-theme="dark"] [style*="color:#1a1a1a"] {
    color: var(--text-primary) !important;
}

[data-theme="dark"] [style*="border-color: #ff3333"],
[data-theme="dark"] [style*="border-color:#ff3333"] {
    border-color: var(--danger) !important;
}