:root {
    --bg: #f5f6f8;
    --bg-panel: #ffffff;
    --bg-stage: #eceef1;
    --text: #1d2129;
    --text-muted: #6b7280;
    --border: #d7dbe0;
    --accent: #2f6fed;
    --accent-soft: rgba(47, 111, 237, 0.12);
    --thumb-border: #c3c9d1;
    --scrollbar: #b8bec7;
}

:root[data-theme="dark"] {
    --bg: #15171b;
    --bg-panel: #1e2127;
    --bg-stage: #101216;
    --text: #e6e8eb;
    --text-muted: #9aa1ab;
    --border: #33373f;
    --accent: #5b8def;
    --accent-soft: rgba(91, 141, 239, 0.18);
    --thumb-border: #454b55;
    --scrollbar: #4a505a;
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --bg: #15171b;
        --bg-panel: #1e2127;
        --bg-stage: #101216;
        --text: #e6e8eb;
        --text-muted: #9aa1ab;
        --border: #33373f;
        --accent: #5b8def;
        --accent-soft: rgba(91, 141, 239, 0.18);
        --thumb-border: #454b55;
        --scrollbar: #4a505a;
    }
}

* {
    box-sizing: border-box;
}

/* The hidden attribute must always win, even over elements styled with
   display: flex (pin gate, viewer footer). */
[hidden] {
    display: none !important;
}

html, body {
    height: 100%;
    margin: 0;
}

body {
    font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
    font-size: 14px;
    background: var(--bg);
    color: var(--text);
    overflow: hidden;
}

#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* ---------- PIN gate ---------- */

/* While locked, hide everything but the overlay so no images ever show. */
#app.locked #app-header,
#app.locked #content {
    display: none;
}

#pin-gate {
    position: fixed;
    inset: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg);
}

#pin-form {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 12px;
    width: 280px;
    max-width: 90vw;
    padding: 28px;
    background: var(--bg-panel);
    border: 1px solid var(--border);
    border-radius: 12px;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.18);
    text-align: center;
}

#pin-title {
    margin: 0;
    font-size: 18px;
    font-weight: 600;
}

#pin-prompt {
    margin: 0;
    color: var(--text-muted);
}

#pin-input {
    padding: 10px 12px;
    font-size: 18px;
    text-align: center;
    letter-spacing: 4px;
    color: var(--text);
    background: var(--bg-stage);
    border: 1px solid var(--border);
    border-radius: 8px;
}

#pin-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 2px var(--accent-soft);
}

#pin-submit {
    padding: 10px 12px;
    font-size: 15px;
    font-weight: 600;
    color: #fff;
    background: var(--accent);
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

#pin-submit:hover {
    filter: brightness(1.08);
}

#pin-error {
    color: #d64545;
    font-size: 13px;
}

/* ---------- Header ---------- */

#app-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 0 12px;
    height: 44px;
    flex: 0 0 auto;
    background: var(--bg-panel);
    border-bottom: 1px solid var(--border);
}

#app-title {
    font-weight: 600;
}

#welcome {
    color: var(--text-muted);
}

/* Push the theme toggle to the far right regardless of the welcome text. */
#theme-toggle {
    margin-left: auto;
}

#theme-toggle,
#logoff {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: transparent;
    color: var(--text);
    cursor: pointer;
}

#theme-toggle:hover,
#logoff:hover {
    background: var(--accent-soft);
}

/* Show the icon of the mode the button switches TO. */
#icon-moon { display: none; }
.theme-dark-active #icon-moon { display: none; }
.theme-dark-active #icon-sun { display: block; }
.theme-light-active #icon-sun { display: none; }
.theme-light-active #icon-moon { display: block; }

/* ---------- Split layout ---------- */

#content {
    display: flex;
    flex: 1 1 auto;
    min-height: 0;
}

#folder-pane {
    width: 280px;
    min-width: 140px;
    max-width: 60vw;
    flex: 0 0 auto;
    overflow: auto;
    background: var(--bg-panel);
    padding: 8px 4px;
}

#splitter {
    flex: 0 0 6px;
    cursor: col-resize;
    background: var(--border);
}

#splitter:hover,
#splitter.dragging {
    background: var(--accent);
}

#viewer-pane {
    display: flex;
    flex-direction: column;
    flex: 1 1 auto;
    min-width: 0;
}

/* ---------- Folder tree ---------- */

.tree-children {
    padding-left: 18px;
}

.tree-row {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 3px 6px;
    border-radius: 6px;
    cursor: pointer;
    user-select: none;
    white-space: nowrap;
}

.tree-row:hover {
    background: var(--accent-soft);
}

.tree-row.selected {
    background: var(--accent);
    color: #fff;
}

.tree-expander {
    display: inline-flex;
    width: 16px;
    height: 16px;
    align-items: center;
    justify-content: center;
    flex: 0 0 auto;
    color: var(--text-muted);
    transition: transform 0.15s;
}

.tree-row.selected .tree-expander {
    color: inherit;
}

.tree-expander.expanded {
    transform: rotate(90deg);
}

.tree-expander.leaf {
    visibility: hidden;
}

.tree-empty {
    padding: 10px;
    color: var(--text-muted);
}

/* ---------- Image stage ---------- */

#image-stage {
    flex: 1 1 auto;
    min-height: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-stage);
    position: relative;
    overflow: hidden;
}

#main-image {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

#stage-message {
    color: var(--text-muted);
    font-size: 16px;
}

/* ---------- Footer / thumbnails ---------- */

#viewer-footer {
    flex: 0 0 auto;
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    background: var(--bg-panel);
    border-top: 1px solid var(--border);
}

#thumbnails {
    display: flex;
    align-items: center;
    gap: 6px;
    flex: 1 1 auto;
    min-width: 0;
    overflow-x: auto;
    overflow-y: hidden;
    height: 112px;
    scrollbar-width: thin;
    scrollbar-color: var(--scrollbar) transparent;
}

.thumb {
    flex: 0 0 auto;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 104px;
    height: 104px;
    border: 2px solid var(--thumb-border);
    border-radius: 6px;
    background: var(--bg-stage);
    cursor: pointer;
    padding: 0;
    overflow: hidden;
}

.thumb img {
    max-width: 100px;
    max-height: 100px;
    object-fit: contain;
    display: block;
}

.thumb.selected {
    border-color: var(--accent);
    box-shadow: 0 0 0 2px var(--accent-soft);
}

.nav-btn, .dl-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    flex: 0 0 auto;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: transparent;
    color: var(--text);
    cursor: pointer;
    width: 38px;
    height: 56px;
}

.dl-btn {
    height: 38px;
}

.nav-btn:hover:not(:disabled), .dl-btn:hover:not(:disabled) {
    background: var(--accent-soft);
    border-color: var(--accent);
}

.nav-btn:disabled, .dl-btn:disabled {
    opacity: 0.35;
    cursor: default;
}

#download-buttons {
    display: flex;
    flex-direction: column;
    gap: 4px;
    border-left: 1px solid var(--border);
    padding-left: 8px;
}