:root[data-theme='light'] {
    --bg-color: #f4f6fb;
    --bg-color-elevated: #ffffff;
    --surface-color: #ffffff;
    --text-color: #1f2430;
    --text-muted: #5b6472;
    --border-color: #e2e6ef;
    --hover-bg: #eef1f8;
    --table-stripe: #f7f9fd;
    --link-color: #3b5bdb;
    --accent-color: #3b5bdb;
    --accent-color-soft: #e8ecfd;
    --shadow-color: rgba(31, 36, 48, 0.08);
    --env-badge-dev-bg: #f59f00;
    --env-badge-dev-text: #1a1a1a;
    --env-badge-staging-bg: #7048e8;
    --env-badge-staging-text: #ffffff;
}

:root[data-theme='dark'] {
    --bg-color: #0f1320;
    --bg-color-elevated: #171c2c;
    --surface-color: #171c2c;
    --text-color: #e7eaf3;
    --text-muted: #9aa3b5;
    --border-color: #2a3145;
    --hover-bg: #202742;
    --table-stripe: #1c2238;
    --link-color: #7c9bff;
    --accent-color: #7c9bff;
    --accent-color-soft: #232c4d;
    --shadow-color: rgba(0, 0, 0, 0.4);
    --env-badge-dev-bg: #f59f00;
    --env-badge-dev-text: #1a1a1a;
    --env-badge-staging-bg: #7048e8;
    --env-badge-staging-text: #ffffff;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
    line-height: 1.6;
    margin: 0;
}

code, pre {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

a {
    color: var(--link-color);
}

.valid.modified:not([type=checkbox]) {
    outline: 1px solid #26b050;
}

.invalid {
    outline: 1px solid red;
}

.validation-message {
    color: red;
}

#blazor-error-ui {
    color-scheme: light only;
    background: lightyellow;
    bottom: 0;
    box-shadow: 0 -1px 2px rgba(0, 0, 0, 0.2);
    box-sizing: border-box;
    display: none;
    left: 0;
    padding: 0.6rem 1.25rem 0.7rem 1.25rem;
    position: fixed;
    width: 100%;
    z-index: 1000;
}

    #blazor-error-ui .dismiss {
        cursor: pointer;
        position: absolute;
        right: 0.75rem;
        top: 0.5rem;
    }

.blazor-error-boundary {
    background: url(data:image/svg+xml;base64,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) no-repeat 1rem/1.8rem, #b32121;
    padding: 1rem 1rem 1rem 3.7rem;
    color: white;
}

    .blazor-error-boundary::after {
        content: "An error has occurred."
    }

.loading-progress {
    position: absolute;
    display: block;
    width: 8rem;
    height: 8rem;
    inset: 20vh 0 auto 0;
    margin: 0 auto 0 auto;
}

    .loading-progress circle {
        fill: none;
        stroke: #e0e0e0;
        stroke-width: 0.6rem;
        transform-origin: 50% 50%;
        transform: rotate(-90deg);
    }

        .loading-progress circle:last-child {
            stroke: #1b6ec2;
            stroke-dasharray: calc(3.141 * var(--blazor-load-percentage, 0%) * 0.8), 500%;
            transition: stroke-dasharray 0.05s ease-in-out;
        }

.loading-progress-text {
    position: absolute;
    text-align: center;
    font-weight: bold;
    inset: calc(20vh + 3.25rem) 0 auto 0.2rem;
}

    .loading-progress-text:after {
        content: var(--blazor-load-percentage-text, "Loading");
    }

.form-floating > .form-control-plaintext::placeholder, .form-floating > .form-control::placeholder {
    color: var(--bs-secondary-color);
    text-align: end;
}

.form-floating > .form-control-plaintext:focus::placeholder, .form-floating > .form-control:focus::placeholder {
    text-align: start;
}

.app-shell { display: flex; flex-direction: column; min-height: 100vh; }
.app-header { display: flex; align-items: center; padding: 0.75rem 1rem; border-bottom: 1px solid var(--border-color); }
.app-header-spacer { flex: 1; }
.app-title {
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-color);
    text-decoration: none;
}
.app-title:hover,
.app-title:focus-visible {
    color: var(--accent-color);
}
.app-title:focus-visible {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
    border-radius: 4px;
}
.environment-badge {
    display: inline-block;
    margin-left: 0.5rem;
    padding: 0.15rem 0.5rem;
    border-radius: 999px;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    vertical-align: middle;
}
.environment-badge--dev {
    background: var(--env-badge-dev-bg);
    color: var(--env-badge-dev-text);
}
.environment-badge--staging {
    background: var(--env-badge-staging-bg);
    color: var(--env-badge-staging-text);
}
.app-body { display: flex; flex: 1; align-items: flex-start; }
.app-sidebar {
    width: 280px;
    flex-shrink: 0;
    align-self: flex-start;
    position: sticky;
    top: 1rem;
    max-height: calc(100vh - 2rem);
    overflow-y: auto;
    margin: 1rem 0 1rem 1rem;
    padding: 1rem;
    background: var(--bg-color-elevated);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: 0 4px 16px var(--shadow-color);
}
.app-main { flex: 1; padding: 1.5rem 2rem; max-width: 900px; }
.app-footer {
    padding: 0.75rem 1rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.8rem;
    text-align: center;
}
.app-footer-version {
    font-variant-numeric: tabular-nums;
    color: inherit;
    text-decoration: none;
    border-bottom: 1px dotted var(--text-muted);
}
.app-footer-version:hover {
    border-bottom-style: solid;
    color: var(--accent-color);
}
.nav-path { margin-bottom: 1.5rem; }
.nav-path-title { margin: 0 0 0.5rem 0; font-size: 1rem; }
.nav-path-title a { text-decoration: none; color: inherit; }
.nav-module { margin-bottom: 1rem; }
.nav-module-title { display: block; font-weight: 600; margin-bottom: 0.25rem; }
.nav-lesson-list { list-style: none; margin: 0; padding-left: 0.75rem; }
.nav-lesson-link {
    display: block;
    padding: 0.3rem 0.5rem;
    border-radius: 6px;
    text-decoration: none;
    color: var(--text-color);
}
.nav-lesson-link:hover {
    background: var(--hover-bg);
}
.nav-lesson-link.active {
    background: var(--accent-color-soft);
    color: var(--accent-color);
    font-weight: 600;
}
.nav-lesson-check {
    display: inline-block;
    width: 1rem;
    color: var(--accent-color);
    font-weight: 700;
}
.nav-lesson-link--completed {
    color: var(--text-muted);
}
.nav-module-title.active {
    color: var(--accent-color);
}
.breadcrumbs { margin-bottom: 1rem; font-size: 0.9rem; }
.exercise-section { margin-top: 2rem; padding: 1rem; border: 1px solid var(--border-color); border-radius: 4px; }
.solution-disclosure { margin-top: 0.75rem; }
.prev-next { display: flex; justify-content: space-between; margin-top: 2rem; }
.complete-toggle { display: inline-flex; align-items: center; gap: 0.4rem; margin-top: 1rem; }
.nav-overall-progress { font-size: 0.85rem; opacity: 0.8; margin: 0 0 0.75rem 0; }
.nav-module-progress { font-size: 0.8rem; opacity: 0.7; margin-left: 0.35rem; }
.resume-banner { margin-bottom: 1.5rem; }
.resume-button { display: inline-block; padding: 0.5rem 1rem; border: 1px solid var(--border-color); border-radius: 4px; text-decoration: none; }
.search-box { position: relative; margin-left: 1rem; }
.search-box input[type="search"] { padding: 0.4rem 0.6rem; min-width: 220px; }
.search-results { position: absolute; top: 100%; left: 0; right: 0; background: var(--surface-color); border: 1px solid var(--border-color); max-height: 60vh; overflow-y: auto; list-style: none; margin: 0.25rem 0 0; padding: 0; z-index: 20; }
.search-results li a { display: block; padding: 0.5rem 0.75rem; text-decoration: none; color: inherit; }
.search-results li a:hover { background: var(--hover-bg); }
.search-result-module { font-size: 0.75rem; opacity: 0.65; margin-left: 0.4rem; }
.search-result-snippet { font-size: 0.8rem; opacity: 0.75; margin-top: 0.15rem; }
.search-result-snippet mark {
    background: var(--accent-color-soft);
    color: var(--accent-color);
    padding: 0 2px;
    border-radius: 2px;
}
.theme-toggle { margin-left: 1rem; padding: 0.4rem 0.75rem; border: 1px solid var(--border-color); border-radius: 4px; background: var(--surface-color); color: var(--text-color); cursor: pointer; }
.history-toggle {
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 0.3rem 0.6rem;
    cursor: pointer;
    color: var(--text-color);
}
.history-panel { margin-top: 1rem; }
.history-timeline { list-style: none; margin: 0; padding: 0; }
.history-entry {
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-bottom: 0.35rem;
    color: var(--text-color);
}
.history-entry summary {
    padding: 0.4rem 0.6rem;
    cursor: pointer;
    list-style: none;
}
.history-entry summary::-webkit-details-marker { display: none; }
.history-entry[open] summary { border-bottom: 1px solid var(--border-color); }
.history-entry-date { font-size: 0.8rem; opacity: 0.7; margin-right: 0.5rem; }
.history-entry-ai-badge { font-size: 0.75rem; margin-right: 0.5rem; }
.history-diff {
    font-family: var(--font-mono, ui-monospace, monospace);
    font-size: 0.8rem;
    padding: 0.5rem 0.6rem;
    overflow-x: auto;
}
.history-diff-empty { padding: 0.4rem 0.6rem; opacity: 0.7; font-size: 0.85rem; }
.diff-line { white-space: pre-wrap; padding: 0 0.25rem; }
.diff-line--hunk { opacity: 0.65; font-style: italic; margin: 0.25rem 0; }
.diff-line--add { background: rgba(46, 160, 67, 0.18); }
.diff-line--del { background: rgba(248, 81, 73, 0.18); }
.diff-line--context { opacity: 0.75; }

.about-build-info { opacity: 0.8; margin-bottom: 1.5rem; }
.changelog-release-list { list-style: none; margin: 0; padding: 0; }
.changelog-release {
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-bottom: 0.75rem;
    color: var(--text-color);
}
.changelog-release summary {
    padding: 0.6rem 0.8rem;
    cursor: pointer;
    list-style: none;
    font-weight: 600;
}
.changelog-release summary::-webkit-details-marker { display: none; }
.changelog-release[open] summary { border-bottom: 1px solid var(--border-color); }
.changelog-release-version { margin-right: 0.5rem; }
.changelog-release-date { font-weight: normal; opacity: 0.7; font-size: 0.85rem; margin-right: 0.5rem; }
.changelog-release-tag { font-weight: normal; opacity: 0.55; font-size: 0.8rem; font-family: var(--font-mono, ui-monospace, monospace); }
.changelog-merge-list { list-style: none; margin: 0; padding: 0.5rem 0.8rem 0.8rem; }
.changelog-merge {
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-bottom: 0.4rem;
}
.changelog-merge summary {
    padding: 0.4rem 0.6rem;
    cursor: pointer;
    list-style: none;
    font-size: 0.9rem;
}
.changelog-merge summary::-webkit-details-marker { display: none; }
.changelog-merge[open] summary { border-bottom: 1px solid var(--border-color); }
.changelog-commit-list { list-style: none; margin: 0; padding: 0.4rem 0.6rem; }
.changelog-commit { padding: 0.3rem 0; border-top: 1px solid var(--border-color); }
.changelog-commit:first-child { border-top: none; }
.changelog-commit-header { display: flex; align-items: baseline; flex-wrap: wrap; gap: 0.35rem; }
.changelog-commit-subject { font-size: 0.9rem; }
.changelog-commit-body {
    font-family: var(--font-mono, ui-monospace, monospace);
    font-size: 0.8rem;
    white-space: pre-wrap;
    margin: 0.3rem 0 0;
    opacity: 0.85;
}
.changelog-empty { padding: 0.5rem 0.8rem; opacity: 0.7; font-size: 0.85rem; }

.app-main h1 { font-size: 2rem; margin-top: 0; }
.app-main h2 { font-size: 1.5rem; margin-top: 2rem; }
.app-main h3 { font-size: 1.25rem; margin-top: 1.5rem; }
.app-main p { margin: 0.75rem 0; }
.app-main code {
    background: var(--hover-bg);
    padding: 0.15rem 0.35rem;
    border-radius: 4px;
    font-size: 0.9em;
}
.app-main pre {
    background: var(--hover-bg);
    padding: 1rem;
    border-radius: 8px;
    overflow-x: auto;
}
.app-main pre code { background: none; padding: 0; }
.app-main blockquote {
    margin: 1rem 0;
    padding: 0.5rem 1rem;
    border-left: 3px solid var(--accent-color);
    background: var(--hover-bg);
    color: var(--text-muted);
}

.app-main table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
}
.app-main th, .app-main td {
    border: 1px solid var(--border-color);
    padding: 0.5rem 0.75rem;
    text-align: left;
}
.app-main th {
    background: var(--hover-bg);
    font-weight: 600;
}
.app-main tbody tr:nth-child(even) td {
    background: var(--table-stripe);
}

.last-updated {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 4px;
    width: 2.25rem;
    height: 2.25rem;
    background: none;
    border: none;
    cursor: pointer;
    margin-right: 0.5rem;
    padding: 0;
}
.nav-toggle-bar {
    display: block;
    height: 2px;
    background: var(--text-color);
    border-radius: 1px;
}
.app-sidebar-backdrop {
    display: none;
}

.app-header-link {
    margin-left: 0.5rem;
    text-decoration: none;
    color: var(--text-color);
    font-size: 0.9rem;
}
.app-header-link:hover {
    color: var(--accent-color);
}

.asset-path {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin: 0 0 1rem 0;
    word-break: break-all;
}
.asset-source {
    background: var(--hover-bg);
    padding: 1rem;
    border-radius: 8px;
    overflow-x: auto;
}
.asset-source code {
    background: none;
    padding: 0;
}
.source-note {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}
.source-download-footer {
    margin-top: 1.5rem;
}

.dir-listing {
    list-style: none;
    margin: 0;
    padding: 0;
}
.dir-listing li {
    padding: 0.3rem 0;
    border-bottom: 1px solid var(--border-color);
}
.dir-listing li a {
    text-decoration: none;
    color: var(--link-color);
}
.dir-listing li a:hover {
    text-decoration: underline;
}

.download-card {
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
    background: var(--bg-color-elevated);
    box-shadow: 0 4px 16px var(--shadow-color);
    max-width: 640px;
}
.download-card-meta {
    list-style: none;
    margin: 0.5rem 0 1rem 0;
    padding: 0;
    display: flex;
    gap: 1.25rem;
    flex-wrap: wrap;
    font-size: 0.85rem;
    color: var(--text-muted);
}
.download-units {
    margin: 0;
    padding-left: 1.1rem;
    font-size: 0.85rem;
}
.download-row-disabled {
    color: var(--text-muted);
}

@media (max-width: 900px) {
    .nav-toggle { display: flex; }
    .app-sidebar {
        position: fixed;
        top: 0;
        left: 0;
        bottom: 0;
        z-index: 40;
        transform: translateX(-100%);
        transition: transform 0.2s ease-in-out;
        width: 280px;
        margin: 0 !important;
    }
    .app-sidebar--open {
        transform: translateX(0);
    }
    .app-sidebar-backdrop {
        display: block;
        position: fixed;
        inset: 0;
        background: rgba(0, 0, 0, 0.4);
        z-index: 30;
    }
    .app-main {
        max-width: 100%;
        padding: 1rem;
    }
}