@font-face {
    font-family: 'Inter';
    src: url('fonts/InterVariable.woff2') format('woff2') tech('variations');
    font-weight: 100 900;
    font-style: normal;
    font-display: swap;
  }
  @font-face {
    font-family: 'Inter';
    src: url('fonts/InterVariable-Italic.woff2') format('woff2') tech('variations');
    font-weight: 100 900;
    font-style: italic;
    font-display: swap;
  }
  *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
  :root {
    --bg: #1e1e1e;
    --slide-bg: #ffffff;
    --text: #2e3436;
    --text-light: #77767b;
    --accent: #3584e4;
    --accent-hover: #62a0ea;
    --header-bg: #3584e4;
    --header-text: #ffffff;
    --footer-bg: #f6f5f4;
    --footer-text: #5e5c64;
    --nav-bg: rgba(0,0,0,0.5);
    --nav-hover: rgba(0,0,0,0.7);
    --radius: 12px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --slide-aspect: 16 / 9;

    /* libadwaita colour variables — used by podium stylesheets */
    --blue-1: #99c1f1;
    --blue-2: #62a0ea;
    --blue-3: #3584e4;
    --blue-4: #1c71d8;
    --blue-5: #1a5fb4;
    --green-1: #8ff0a4;
    --green-2: #57e389;
    --green-3: #33d17a;
    --green-4: #2ec27e;
    --green-5: #26a269;
    --yellow-1: #f9f06b;
    --yellow-2: #f8e45c;
    --yellow-3: #f6d32d;
    --yellow-4: #f5c211;
    --yellow-5: #e5a50a;
    --orange-1: #ffbe6f;
    --orange-2: #ffa348;
    --orange-3: #ff7800;
    --orange-4: #e66100;
    --orange-5: #c64600;
    --red-1: #f66151;
    --red-2: #ed333b;
    --red-3: #e01b24;
    --red-4: #c01c28;
    --red-5: #a51d2d;
    --purple-1: #c061cb;
    --purple-2: #9141ac;
    --purple-3: #813d9c;
    --purple-4: #613583;
    --purple-5: #4d2868;
    --brown-1: #cdab8f;
    --brown-2: #b5835a;
    --brown-3: #986a44;
    --brown-4: #785336;
    --brown-5: #633b1c;
    --light-1: #ffffff;
    --light-2: #f6f5f4;
    --light-3: #deddda;
    --light-4: #c0bfbc;
    --light-5: #9a9996;
    --dark-1: #77767b;
    --dark-2: #5e5c64;
    --dark-3: #3d3846;
    --dark-4: #241f31;
    --dark-5: #1e1e2e;
  }

  html, body {
    height: 100%;
    font-family: var(--font);
    background: var(--bg);
    color: #fff;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
  }

  /* ─── Landing ─── */
  #landing {
    position: fixed;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 100;
    background: var(--bg);
    transition: opacity 0.4s, visibility 0.4s;
  }
  #landing.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
  }
  #landing h1 {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.25rem;
  }
  #landing h1 span { color: var(--accent); }
  #landing p.sub {
    color: var(--text-light);
    font-size: 0.95rem;
    margin-bottom: 2.5rem;
  }

  .drop-zone {
    width: min(90vw, 480px);
    padding: 3rem 2rem;
    border: 2px dashed rgba(255,255,255,0.2);
    border-radius: var(--radius);
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s, background 0.2s;
    position: relative;
  }
  .drop-zone:hover,
  .drop-zone.dragover {
    border-color: var(--accent);
    background: rgba(53, 132, 228, 0.08);
  }
  .drop-zone .icon {
    margin-bottom: 0.75rem;
    display: flex;
    justify-content: center;
  }
  .drop-zone .icon img {
    width: 64px;
    height: 64px;
  }
  .drop-zone .label { font-weight: 500; margin-bottom: 0.25rem; }
  .drop-zone .hint { font-size: 0.8rem; color: var(--text-light); }
  .drop-zone input[type=file] {
    position: absolute; inset: 0; opacity: 0; cursor: pointer;
  }

  .alt-input {
    margin-top: 1.5rem;
    font-size: 0.85rem;
    color: var(--text-light);
  }
  .alt-input a {
    color: var(--accent);
    text-decoration: none;
    cursor: pointer;
  }
  .alt-input a:hover { text-decoration: underline; }

  /* markdown textarea modal */
  #md-modal {
    position: fixed; inset: 0; z-index: 200;
    background: rgba(0,0,0,0.7);
    display: none;
    align-items: center;
    justify-content: center;
  }
  #md-modal.open { display: flex; }
  #md-modal .panel {
    background: #2e2e2e;
    border-radius: var(--radius);
    width: min(90vw, 700px);
    max-height: 80vh;
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
  }
  #md-modal .panel h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
  }
  #md-modal textarea {
    flex: 1;
    min-height: 300px;
    background: #1e1e1e;
    color: #e0e0e0;
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 8px;
    padding: 1rem;
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', monospace;
    font-size: 0.85rem;
    line-height: 1.6;
    resize: vertical;
    tab-size: 2;
  }
  #md-modal textarea:focus { outline: none; border-color: var(--accent); }
  #md-modal .actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
    margin-top: 0.75rem;
  }
  #md-modal button {
    padding: 0.5rem 1.25rem;
    border: none;
    border-radius: 6px;
    font-family: var(--font);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.15s;
  }
  #md-modal .btn-primary {
    background: var(--accent);
    color: #fff;
  }
  #md-modal .btn-primary:hover { background: var(--accent-hover); }
  #md-modal .btn-secondary {
    background: rgba(255,255,255,0.1);
    color: #ccc;
  }
  #md-modal .btn-secondary:hover { background: rgba(255,255,255,0.15); }
  #md-modal .error {
    color: #e01b24;
    font-size: 0.8rem;
    margin-top: 0.5rem;
    display: none;
  }

  /* ─── Viewer ─── */
  #viewer {
    position: fixed;
    inset: 0;
    display: none;
    flex-direction: column;
  }
  #viewer.active { display: flex; }

  /* Top bar */
  #topbar {
    display: flex;
    align-items: center;
    padding: 0.5rem 1rem;
    background: rgba(0,0,0,0.3);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    gap: 0.75rem;
    flex-shrink: 0;
    z-index: 10;
  }
  #topbar .brand {
    font-weight: 600;
    font-size: 0.9rem;
    color: rgba(255,255,255,0.7);
  }
  #topbar .brand span { color: var(--accent); }
  #topbar .filename {
    font-size: 0.8rem;
    color: rgba(255,255,255,0.4);
    margin-left: 0.5rem;
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }
  #topbar .spacer { flex: 1; }
  #topbar button {
    background: none;
    border: none;
    color: rgba(255,255,255,0.6);
    font-size: 1.1rem;
    cursor: pointer;
    padding: 0.3rem 0.5rem;
    border-radius: 6px;
    transition: background 0.15s, color 0.15s;
    line-height: 1;
  }
  #topbar button:hover {
    background: rgba(255,255,255,0.1);
    color: #fff;
  }

  /* Slide area */
  #slide-area {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    padding: 2rem;
  }

  #slide-frame {
    position: relative;
    width: 100%;
    max-width: 1280px;
    --podium-scale: 1;
    aspect-ratio: var(--slide-aspect);
    background: var(--slide-bg);
    border-radius: var(--radius);
    box-shadow: 0 20px 60px rgba(0,0,0,0.5);
    overflow: hidden;
    transition: opacity 0.25s ease;
  }
  #slide-frame.fading { opacity: 0; }

  #slide-content {
    width: 100%;
    height: 100%;
    padding: 4rem 5rem;
    overflow: hidden;
    color: var(--text);
    font-size: 1.4rem;
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    position: relative;
  }
  #slide-content.has-media { padding: 0; }

  /* Podium header/footer overlays */
  .slide-header, .slide-footer {
    position: absolute;
    left: 0; right: 0;
    z-index: 5;
    pointer-events: none;
  }
  .slide-header {
    top: 0;
    background: transparent;
    color: #ffffff;
    padding: 0.5rem 5rem;
    font-size: 0.75rem;
    font-weight: 500;
    text-align: center;
    text-transform: uppercase;
    letter-spacing: 0.05em;
  }
  .slide-footer {
    bottom: 0;
    background: transparent;
    color: #ffffff;
    padding: 0.4rem 5rem;
    font-size: 0.7rem;
    font-weight: 400;
    text-align: center;
  }

  /* Markdown rendered styles */
  #slide-content.title-and-list {
    align-items: flex-start;
    text-align: left;
    padding: 4rem 5rem;
  }
  #slide-content.title-and-list h1 {
    margin-bottom: 1.5rem;
    width: 100%;
  }
  #slide-content.title-and-list h2,
  #slide-content.title-and-list h3 {
    width: 100%;
  }

  #slide-content h1 {
    font-size: 2.8rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.2;
    margin-bottom: 0.5rem;
  }
  #slide-content h2 {
    font-size: 1.8rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.3;
    margin-bottom: 0.4rem;
  }
  #slide-content h3 {
    font-size: 1.4rem;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 0.3rem;
  }
  #slide-content h4, #slide-content h5, #slide-content h6 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.3rem;
  }
  #slide-content p { margin-bottom: 0.75rem; }
  #slide-content p:last-child { margin-bottom: 0; }
  #slide-content ul, #slide-content ol {
    margin-left: 1.5rem;
    margin-bottom: 0.75rem;
  }
  #slide-content li { margin-bottom: 0.25rem; }
  #slide-content strong { font-weight: 700; }
  #slide-content em { font-style: italic; }
  #slide-content code {
    background: #f0f0f0;
    padding: 0.15em 0.4em;
    border-radius: 4px;
    font-size: 0.85em;
    font-family: 'SF Mono', 'Fira Code', monospace;
  }
  #slide-content pre {
    background: #f6f5f4;
    border-radius: 8px;
    padding: 1rem;
    overflow-x: auto;
    margin-bottom: 0.75rem;
  }
  #slide-content pre code {
    background: none;
    padding: 0;
    font-size: 0.8rem;
  }
  #slide-content img {
    max-width: 100%;
    max-height: 100%;
    display: block;
  }
  #slide-content blockquote {
    border-left: 4px solid var(--accent);
    padding-left: 1rem;
    color: #5e5c64;
    margin-bottom: 0.75rem;
  }
  #slide-content hr {
    border: none;
    border-top: 2px solid #e0e0e0;
    margin: 1rem 0;
  }

  /* Media slide (image fills) */
  #slide-content.media-bg {
    padding: 0;
    justify-content: stretch;
    align-items: stretch;
  }
  #slide-content.media-bg img {
    width: 100%;
    height: 100%;
    object-fit: cover;
  }
  #slide-content.media-bg.media-contain img { object-fit: contain; }
  #slide-content.media-bg.media-fill img { object-fit: fill; }
  #slide-content.media-bg.media-scale-down img { object-fit: scale-down; }

  #slide-content.media-foreground {
    display: grid;
    grid-template-rows: auto 1fr auto;
    padding: 0;
  }
  #slide-content.media-foreground .media-titles {
    padding: 2rem 4rem 0;
    text-align: center;
  }
  #slide-content.media-foreground .media-fig {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem 2rem;
    overflow: hidden;
  }
  #slide-content.media-foreground .media-fig img,
  #slide-content.media-foreground .media-fig video {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
  }
  /* Navigation arrows */
  .nav-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 48px;
    height: 48px;
    border: none;
    border-radius: 50%;
    background: var(--nav-bg);
    color: #fff;
    font-size: 1.4rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.25s, background 0.15s;
    z-index: 20;
    backdrop-filter: blur(4px);
  }
  .nav-arrow:focus-visible,
  #slide-area:hover .nav-arrow { opacity: 1; }
  .nav-arrow:hover { background: var(--nav-hover); }
  .nav-arrow:active { transform: translateY(-50%) scale(0.92); }
  .nav-arrow.prev { left: 1.5rem; }
  .nav-arrow.next { right: 1.5rem; }
  .nav-arrow:disabled { opacity: 0 !important; cursor: default; }

  /* Slide counter */
  #counter {
    position: absolute;
    bottom: 1.5rem;
    right: 2rem;
    font-size: 0.8rem;
    color: rgba(255,255,255,0.35);
    font-weight: 500;
    z-index: 15;
    background: rgba(0,0,0,0.3);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    backdrop-filter: blur(4px);
  }

  /* Loading indicator */
  #loading {
    position: fixed; inset: 0; z-index: 300;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(0,0,0,0.6);
    backdrop-filter: blur(8px);
  }
  #loading.active { display: flex; }
  #loading .spinner {
    width: 40px; height: 40px;
    border: 3px solid rgba(255,255,255,0.15);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
  }
  @keyframes spin { to { transform: rotate(360deg); } }
  #loading .msg {
    margin-left: 1rem;
    font-size: 0.9rem;
    color: rgba(255,255,255,0.7);
  }

  /* Toast notifications */
  #toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: #2e2e2e;
    color: #e0e0e0;
    padding: 0.6rem 1.2rem;
    border-radius: 8px;
    font-size: 0.85rem;
    z-index: 400;
    opacity: 0;
    transition: transform 0.3s, opacity 0.3s;
    pointer-events: none;
    box-shadow: 0 4px 20px rgba(0,0,0,0.4);
  }
  #toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
  }
  #toast.error {
    border-left: 3px solid #e01b24;
  }

  /* ─── Fullscreen ─── */
  #viewer.fullscreen #topbar { display: none; }
  #viewer.fullscreen #slide-area { padding: 0; }
  #viewer.fullscreen #slide-frame {
    max-width: none;
    border-radius: 0;
    box-shadow: none;
  }
  #viewer.fullscreen .nav-arrow { display: none; }
  #viewer.fullscreen #counter { bottom: 2rem; right: 2rem; }

  /* ─── Responsive ─── */
  @media (max-width: 768px) {
    #landing h1 { font-size: 1.8rem; }
    .drop-zone { padding: 2rem 1.5rem; }
    #slide-area { padding: 0.5rem; }
    #slide-frame { border-radius: 8px; }
    #slide-content { padding: 2rem 1.5rem; font-size: 1rem; }
    .slide-header { padding: 0.3rem 1.5rem; font-size: 0.65rem; }
    .slide-footer { padding: 0.3rem 1.5rem; font-size: 0.6rem; }
    .nav-arrow { width: 36px; height: 36px; font-size: 1rem; }
    .nav-arrow.prev { left: 0.5rem; }
    .nav-arrow.next { right: 0.5rem; }
    #slide-content h1 { font-size: 1.8rem; }
    #slide-content h2 { font-size: 1.3rem; }
    #slide-content h3 { font-size: 1.1rem; }
  }

  @media (max-width: 480px) {
    #slide-content { padding: 1.5rem 1rem; font-size: 0.85rem; }
    #slide-content.media-foreground .media-titles { padding: 1rem 1rem 0; }
    .slide-header { padding: 0.2rem 1rem; font-size: 0.55rem; }
    .slide-footer { padding: 0.2rem 1rem; font-size: 0.5rem; }
  }

  /* Print - hide chrome */
  @media print {
    #landing, #topbar, .nav-arrow, #counter { display: none !important; }
    #viewer { position: static; display: block !important; }
    #slide-frame { box-shadow: none; border-radius: 0; max-width: 100%; }
    #slide-area { padding: 0; }
  }