:root {
    --primary-color: #117a8b;
    --primary-hover: #0e6573;
    --accent-color: #e8833a;
    --background-color: #f4f6f8;
    --surface-color: #ffffff;
    --text-color: #2d3436;
    --muted-color: #6c757d;
    --border-color: #d9e1e7;
    --editor-bg: #ffffff;
    --code-color: #2d3436;
}

[data-theme="dark"] {
    --primary-color: #2aa1b5;
    --primary-hover: #38b6cb;
    --accent-color: #f0a500;
    --background-color: #181a1b;
    --surface-color: #232728;
    --text-color: #e6e9ea;
    --muted-color: #9aa4a8;
    --border-color: #3a4042;
    --editor-bg: #1e2122;
    --code-color: #e6e9ea;
}

* {
    box-sizing: border-box;
}

html, body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    height: 100vh;
    overflow: hidden;
}

.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    color: var(--primary-color);
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

#blazor-error-ui {
    background: #fff3cd;
    color: #856404;
    padding: 1rem;
    text-align: center;
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 1000;
}

#blazor-error-ui.show,
#blazor-error-ui[style*="display: block"] {
    display: block;
}

#blazor-error-ui a {
    color: #856404;
    margin-left: 0.5rem;
}

/* App shell: a fixed header and footer with a flexible editor area between them. */
.app-shell {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

header {
    background: var(--primary-color);
    color: white;
    padding: 0.85rem 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-shrink: 0;
}

.header-logo {
    height: 2.5rem;
    width: 2.5rem;
    flex-shrink: 0;
    /* The icon ships as a black emblem on a white field, so present it as a rounded white badge. */
    background: #fff;
    border-radius: 8px;
    object-fit: contain;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
}

.header-titles {
    flex: 1;
    min-width: 0;
}

header h1 {
    margin: 0;
    font-size: 1.4rem;
    outline: none;
    letter-spacing: 0.01em;
}

header p {
    margin: 0.15rem 0 0;
    opacity: 0.9;
    font-size: 0.85rem;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-shrink: 0;
}

.header-link {
    color: white;
    opacity: 0.85;
    text-decoration: none;
    font-size: 0.85rem;
}

.header-link:hover {
    opacity: 1;
    text-decoration: underline;
}

.theme-toggle-btn {
    padding: 0.45rem 0.9rem;
    border: 1px solid rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s;
    white-space: nowrap;
}

.theme-toggle-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.5);
}

/* Two-pane editor / preview layout filling the space between header and footer. */
.editor-layout {
    flex: 1;
    display: flex;
    min-height: 0;
    gap: 1px;
    background: var(--border-color);
}

.editor-pane,
.preview-pane {
    flex: 1 1 50%;
    min-width: 0;
    display: flex;
    flex-direction: column;
    background: var(--surface-color);
}

.pane-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.6rem 1rem;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
    min-height: 3rem;
}

.pane-title {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-color);
}

/* Deep-link to the Mermaid syntax reference for the diagram type currently in the editor. */
.doc-link {
    font-size: 0.8rem;
    color: var(--primary-color);
    text-decoration: none;
    white-space: nowrap;
}

.doc-link:hover {
    text-decoration: underline;
}

.pane-spacer {
    flex: 1;
}

/* Sample picker dropdown */
.sample-picker {
    display: flex;
    align-items: center;
}

.sample-select {
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background: var(--background-color);
    color: var(--text-color);
    font-size: 0.85rem;
    max-width: 220px;
}

/* Source editor */
.code-editor {
    flex: 1;
    width: 100%;
    border: 0;
    outline: none;
    resize: none;
    padding: 1rem;
    background: var(--editor-bg);
    color: var(--code-color);
    font-family: 'Cascadia Code', 'Fira Code', 'JetBrains Mono', Consolas, 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    tab-size: 2;
    white-space: pre;
    overflow: auto;
}

/* Preview toolbar */
.toolbar {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.toolbar-btn {
    padding: 0.4rem 0.8rem;
    border: 1px solid var(--border-color);
    background: var(--background-color);
    color: var(--text-color);
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.82rem;
    font-weight: 600;
    transition: border-color 0.2s, background 0.2s;
    white-space: nowrap;
}

.toolbar-btn:hover:not(:disabled) {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.toolbar-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Preview surface — kept light in both themes because Naiad renders diagrams on a light background. */
.preview-surface {
    flex: 1;
    overflow: auto;
    padding: 1.25rem;
    background: #ffffff;
    background-image:
        linear-gradient(45deg, #f0f0f0 25%, transparent 25%),
        linear-gradient(-45deg, #f0f0f0 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, #f0f0f0 75%),
        linear-gradient(-45deg, transparent 75%, #f0f0f0 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0;
}

.preview-content {
    display: flex;
    align-items: flex-start;
    justify-content: center;
    min-height: 100%;
}

.preview-content svg {
    max-width: 100%;
    height: auto;
    background: #ffffff;
    box-shadow: 0 1px 6px rgba(0, 0, 0, 0.15);
    border-radius: 4px;
}

.preview-empty {
    margin: auto;
    color: var(--muted-color);
    font-size: 0.9rem;
    text-align: center;
    padding: 2rem;
}

/* Status bar — a thin strip under the preview reporting facts about the current render. */
.status-bar {
    flex-shrink: 0;
    display: flex;
    align-items: center;
    padding: 0.35rem 1rem;
    border-top: 1px solid var(--border-color);
    background: var(--surface-color);
    color: var(--muted-color);
    font-size: 0.78rem;
}

.status-item {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
    padding: 0 0.85rem;
    white-space: nowrap;
}

.status-item:first-child {
    padding-left: 0;
}

/* Divide each fact from the previous one. */
.status-item:not(:first-child) {
    border-left: 1px solid var(--border-color);
}

.status-metric {
    color: var(--text-color);
    font-weight: 600;
    /* Fixed-width digits keep the figures from shifting as they update on each live re-render. */
    font-variant-numeric: tabular-nums;
}

/* Error panel */
.error {
    margin: 1rem;
    padding: 1rem;
    background: #f8d7da;
    color: #842029;
    border: 1px solid #f5c2c7;
    border-radius: 8px;
    align-self: center;
}

.error-message {
    margin: 0;
    white-space: pre-wrap;
    font-family: 'Cascadia Code', Consolas, monospace;
    font-size: 0.85rem;
}

.error-report {
    margin: 0.75rem 0 0;
    font-size: 0.9rem;
}

.error-report a {
    color: #842029;
    font-weight: 600;
}

footer {
    flex-shrink: 0;
    text-align: center;
    padding: 0.5rem 1rem;
    color: var(--muted-color);
    font-size: 0.8rem;
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

.footer-version {
    margin-left: 0.5rem;
    opacity: 0.7;
}

.footer-size {
    margin-left: 0.5rem;
    opacity: 0.7;
}

.footer-ram {
    margin-left: 0.5rem;
    opacity: 0.7;
}

@media (max-width: 768px) {
    html, body {
        overflow: auto;
    }

    .app-shell {
        height: auto;
        min-height: 100vh;
    }

    header {
        padding: 0.75rem 1rem;
    }

    header h1 {
        font-size: 1.2rem;
    }

    .header-logo {
        height: 2rem;
        width: 2rem;
    }

    header p {
        display: none;
    }

    .header-link {
        display: none;
    }

    /* The footer is tight on a phone-width row; drop the payload-size figure to keep it readable. */
    .footer-size {
        display: none;
    }

    .editor-layout {
        flex-direction: column;
        gap: 1px;
    }

    .editor-pane,
    .preview-pane {
        flex: none;
    }

    .code-editor {
        min-height: 40vh;
    }

    .preview-surface {
        min-height: 40vh;
    }

    .theme-toggle-btn .text {
        display: none;
    }

    .theme-toggle-btn .icon {
        font-size: 1.1rem;
    }

    .sample-select {
        max-width: 150px;
    }
}