/* ═══════════════════════════════════════════════════════════
   APNG Maker – styles
   Dark theme · responsive · no external dependencies
   ═══════════════════════════════════════════════════════════ */

/* ── Variables ────────────────────────────────────────────── */
:root {
    --bg:          #0c0c14;
    --bg-card:     #16162a;
    --bg-card-alt: #1c1c38;
    --bg-hover:    #22224a;
    --border:      #2a2a50;
    --text:        #e2e2f0;
    --text-dim:    #8888aa;
    --accent:      #7c6cf0;
    --accent-light:#a898ff;
    --accent-bg:   rgba(124,108,240,.12);
    --success:     #34d399;
    --danger:      #f87171;
    --radius:      10px;
    --radius-sm:   6px;
    --shadow:      0 4px 24px rgba(0,0,0,.35);
    --transition:  .2s ease;
    --font:        'Segoe UI', system-ui, -apple-system, sans-serif;
}

/* ── Reset & base ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 15px; }
body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.5;
}

img, canvas { display: block; max-width: 100%; }
button { cursor: pointer; font: inherit; }
input, select { font: inherit; }

/* ── App Shell ────────────────────────────────────────────── */
.app {
    max-width: 1100px;
    margin: 0 auto;
    padding: 24px 20px 60px;
}

/* ── Header ───────────────────────────────────────────────── */
.header { text-align: center; padding: 32px 0 18px; }
.header__logo {
    max-width: 400px;
    height: auto;
    margin: 0 auto 4px;
    display: block;
}
.header__title {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--accent-light), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.header__subtitle {
    color: var(--text-dim);
    font-size: .95rem;
    margin-top: 4px;
}

/* ── Tabs ─────────────────────────────────────────────────── */
.tabs {
    display: flex;
    gap: 8px;
    justify-content: center;
    margin-bottom: 24px;
}
.tabs__btn {
    background: var(--bg-card);
    color: var(--text-dim);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 600;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 8px;
}
.tabs__btn:hover { background: var(--bg-hover); color: var(--text); }
.tabs__btn.active {
    background: var(--accent-bg);
    border-color: var(--accent);
    color: var(--accent-light);
}

/* ── Panels ───────────────────────────────────────────────── */
.panel { display: none; }
.panel.active { display: grid; gap: 20px; }

.panel--frames.active {
    grid-template-columns: 1fr 1fr;
    grid-template-rows: auto 1fr;
}
.panel--frames .panel__upload   { grid-column: 1 / -1; }
.panel--frames .panel__frames   { grid-column: 1; }
.panel--frames .panel__settings { grid-column: 2; }

.panel--effects.active {
    grid-template-columns: 280px 1fr;
    grid-template-rows: auto auto;
}
.panel--effects .panel__upload   { grid-column: 1; grid-row: 1; }
.panel--effects .panel__settings { grid-column: 1; grid-row: 2; }
.panel--effects .panel__effects  { grid-column: 2; grid-row: 1 / 3; }

/* ── Upload Zone ──────────────────────────────────────────── */
.upload-zone {
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 36px 20px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background: var(--bg-card);
}
.upload-zone:hover, .upload-zone.drag-over {
    border-color: var(--accent);
    background: var(--accent-bg);
}
.upload-zone__icon { font-size: 2.4rem; margin-bottom: 8px; }
.upload-zone__text { font-weight: 600; font-size: 1rem; }
.upload-zone__hint { color: var(--text-dim); font-size: .82rem; margin-top: 4px; }

/* ── Source preview (effects) ─────────────────────────────── */
.source-preview {
    position: relative;
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 12px;
    text-align: center;
}
.source-preview img {
    max-height: 180px;
    margin: 0 auto;
    border-radius: var(--radius-sm);
}
.source-preview .btn--danger {
    position: absolute;
    top: 8px;
    right: 8px;
}

/* ── Frames list ──────────────────────────────────────────── */
.frames-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
    flex-wrap: wrap;
    gap: 6px;
}
.frames-header h3 { font-size: 1rem; }
.frames-header__actions { display: flex; gap: 4px; }

/* ── Range toggle ─────────────────────────────────────────── */
.range-toggle {
    display: flex;
    align-items: center;
    gap: 6px;
    flex-wrap: wrap;
    background: var(--bg-card-alt);
    border-radius: var(--radius-sm);
    padding: 8px 10px;
    margin-bottom: 8px;
    font-size: .8rem;
}
.range-toggle__label {
    color: var(--text-dim);
    font-weight: 600;
    white-space: nowrap;
}
.range-toggle__field {
    display: flex;
    align-items: center;
    gap: 3px;
    color: var(--text-dim);
    font-size: .78rem;
}
.input-mini {
    width: 48px;
    padding: 2px 5px;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: .8rem;
    text-align: center;
}
.input-mini:focus {
    border-color: var(--accent);
    outline: none;
}

.frames-list {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 12px;
    max-height: 400px;
    overflow-y: auto;
}
.frames-list__empty {
    color: var(--text-dim);
    text-align: center;
    padding: 24px 0;
    font-size: .9rem;
}

.frame-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 8px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}
.frame-item:hover { background: var(--bg-hover); }
.frame-item--disabled {
    opacity: .4;
}
.frame-item--disabled .frame-item__thumb { filter: grayscale(1); }

.frame-item__check {
    accent-color: var(--accent);
    width: 16px;
    height: 16px;
    flex-shrink: 0;
    cursor: pointer;
}

.frame-item__num {
    width: 24px; height: 24px;
    display: grid; place-items: center;
    background: var(--accent-bg);
    color: var(--accent-light);
    font-size: .75rem; font-weight: 700;
    border-radius: 50%;
    flex-shrink: 0;
}
.frame-item__thumb {
    width: 48px; height: 48px;
    border-radius: var(--radius-sm);
    background: var(--bg);
    flex-shrink: 0;
}
.frame-item__name {
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: .85rem;
    color: var(--text-dim);
}
.frame-item__actions { display: flex; gap: 4px; }

/* ── Settings ─────────────────────────────────────────────── */
.panel__settings {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 16px;
    align-self: start;
}
.panel__settings h3 {
    font-size: 1rem;
    margin-bottom: 14px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
}

.setting { margin-bottom: 14px; }
.setting label {
    display: block;
    font-size: .82rem;
    color: var(--text-dim);
    margin-bottom: 4px;
}
.setting label small {
    color: var(--text-dim);
    opacity: .7;
    font-weight: 400;
}
.setting input[type="range"] {
    width: 100%;
    accent-color: var(--accent);
}
.setting select {
    width: 100%;
    padding: 6px 10px;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
}
.setting__value {
    font-size: .82rem;
    color: var(--accent-light);
    font-weight: 600;
}

/* Text input (loop count, etc.) */
.input-text {
    width: 100%;
    padding: 6px 10px;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
}
.input-text:focus {
    border-color: var(--accent);
    outline: none;
}
.input-text::placeholder { color: var(--text-dim); opacity: .6; }

/* Checkbox labels */
.checkbox-label {
    display: flex !important;
    align-items: flex-start;
    gap: 8px;
    cursor: pointer;
    margin-bottom: 0 !important;
}
.checkbox-label input[type="checkbox"] {
    accent-color: var(--accent);
    width: 16px;
    height: 16px;
    margin-top: 1px;
    flex-shrink: 0;
    cursor: pointer;
}

/* Indented sub-setting */
.setting--indent {
    padding-left: 26px;
}

/* Settings divider heading */
.settings-divider {
    font-size: .88rem;
    margin: 18px 0 12px;
    padding-top: 12px;
    padding-bottom: 8px;
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    color: var(--text-dim);
}

/* ── Effects grid ─────────────────────────────────────────── */
.panel__effects h3 {
    font-size: 1rem;
    margin-bottom: 12px;
}
.effects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 10px;
}

.effect-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 10px;
    text-align: center;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    color: var(--text);
}
.effect-card:hover {
    background: var(--bg-hover);
    border-color: var(--accent);
    transform: translateY(-2px);
}
.effect-card.active {
    background: var(--accent-bg);
    border-color: var(--accent);
    box-shadow: 0 0 0 2px var(--accent-bg);
}
.effect-card__icon { font-size: 1.6rem; }
.effect-card__name { font-weight: 600; font-size: .88rem; }
.effect-card__desc { font-size: .72rem; color: var(--text-dim); line-height: 1.3; }

/* ── Buttons ──────────────────────────────────────────────── */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 18px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text);
    font-weight: 600;
    font-size: .9rem;
    transition: var(--transition);
}
.btn:hover { background: var(--bg-hover); }
.btn--small { padding: 4px 12px; font-size: .8rem; }
.btn--large { padding: 12px 32px; font-size: 1rem; }

.btn--primary {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
}
.btn--primary:hover { background: var(--accent-light); }
.btn--primary:disabled {
    opacity: .4;
    cursor: not-allowed;
    background: var(--accent);
}

.btn--success {
    background: var(--success);
    border-color: var(--success);
    color: #0c0c14;
}
.btn--success:hover { filter: brightness(1.15); }

.btn--danger {
    background: transparent;
    border-color: var(--danger);
    color: var(--danger);
}

.btn-icon {
    width: 28px; height: 28px;
    display: grid; place-items: center;
    border-radius: var(--radius-sm);
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-dim);
    font-size: .75rem;
    transition: var(--transition);
}
.btn-icon:hover { background: var(--bg-hover); color: var(--text); border-color: var(--border); }
.btn-icon--danger:hover { color: var(--danger); border-color: var(--danger); }

/* ── Output / Preview ─────────────────────────────────────── */
.output {
    margin-top: 28px;
    display: flex;
    gap: 20px;
    align-items: flex-start;
}

.preview {
    flex: 1;
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 16px;
}
.preview h3 { font-size: 1rem; margin-bottom: 10px; }

.preview__canvas-wrap {
    background: repeating-conic-gradient(#1a1a2e 0% 25%, #22224a 0% 50%) 
                50% / 20px 20px;
    border-radius: var(--radius-sm);
    min-height: 120px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    position: relative;
}
.preview__canvas-wrap canvas,
.preview__canvas-wrap .preview__final {
    max-width: 100%;
    max-height: 360px;
    image-rendering: auto;
}
.preview__final {
    position: absolute; top: 0; left: 0;
    width: 100%; height: 100%;
    object-fit: contain;
}
.preview__info {
    margin-top: 8px;
    font-size: .8rem;
    color: var(--text-dim);
    text-align: center;
}

.export {
    display: flex;
    flex-direction: column;
    gap: 10px;
    min-width: 200px;
    align-items: stretch;
}

/* ── Progress bar ─────────────────────────────────────────── */
.progress {
    background: var(--bg-card);
    border-radius: var(--radius);
    overflow: hidden;
    height: 32px;
    position: relative;
}
.progress__bar {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), var(--accent-light));
    transition: width .15s;
    border-radius: var(--radius);
}
.progress__text {
    position: absolute;
    inset: 0;
    display: grid;
    place-items: center;
    font-size: .8rem;
    font-weight: 600;
    color: var(--text);
    text-shadow: 0 1px 4px rgba(0,0,0,.6);
}

/* ── Filters Panel ────────────────────────────────────────── */
.filters-panel {
    margin-top: 28px;
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
}
.filters-panel__title {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 14px 18px;
    font-size: 1.05rem;
    font-weight: 700;
    cursor: pointer;
    user-select: none;
    transition: var(--transition);
    margin: 0;
}
.filters-panel__title:hover { background: var(--bg-hover); }
.filters-panel__arrow {
    margin-left: auto;
    font-size: 1.2rem;
    color: var(--text-dim);
}
.filters-panel__body {
    padding: 0 18px 18px;
}

/* Filter sections */
.filter-section {
    margin-bottom: 18px;
    padding-bottom: 14px;
    border-bottom: 1px solid var(--border);
}
.filter-section:last-child { border-bottom: none; margin-bottom: 0; padding-bottom: 0; }
.filter-section h4 {
    font-size: .88rem;
    color: var(--accent-light);
    margin-bottom: 10px;
    font-weight: 600;
}
.filter-section--actions {
    text-align: right;
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.filter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 12px 16px;
}
.filter-item label {
    display: block;
    font-size: .78rem;
    color: var(--text-dim);
    margin-bottom: 3px;
}
.filter-item label small { opacity: .7; }
.filter-item input[type="range"] {
    width: 100%;
    accent-color: var(--accent);
}
.filter-item--wide {
    grid-column: 1 / -1;
}
.filter-item--inline {
    display: flex;
    align-items: center;
    gap: 8px;
    flex: 1;
    min-width: 200px;
}
.filter-item--inline label {
    white-space: nowrap;
    margin-bottom: 0;
}
.filter-item--inline input[type="range"] {
    flex: 1;
}

.filter-val {
    font-size: .78rem;
    color: var(--accent-light);
    font-weight: 600;
    margin-left: 4px;
}

.filter-checks {
    display: flex;
    flex-wrap: wrap;
    gap: 10px 18px;
    margin-top: 10px;
}

/* Preset buttons */
.preset-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}
.preset-btn {
    padding: 5px 14px;
    border-radius: 20px;
    border: 1px solid var(--border);
    background: var(--bg-card-alt);
    color: var(--text-dim);
    font-size: .78rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}
.preset-btn:hover {
    background: var(--bg-hover);
    color: var(--text);
    border-color: var(--accent);
}
.preset-btn.active {
    background: var(--accent-bg);
    border-color: var(--accent);
    color: var(--accent-light);
}

/* Color picker */
.color-picker {
    width: 40px;
    height: 32px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg);
    cursor: pointer;
    padding: 2px;
}
.color-picker::-webkit-color-swatch-wrapper { padding: 0; }
.color-picker::-webkit-color-swatch { border: none; border-radius: 3px; }

/* Utility classes */
.flex-row {
    display: flex;
    align-items: center;
    gap: 8px;
}
.flex-wrap {
    flex-wrap: wrap;
}
.input-mini-wide {
    width: 72px;
    padding: 4px 8px;
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: .85rem;
    text-align: center;
}
.input-mini-wide:focus {
    border-color: var(--accent);
    outline: none;
}
.text-dim {
    color: var(--text-dim);
    font-size: .82rem;
}
.small-label {
    font-size: .78rem;
    color: var(--text-dim);
    white-space: nowrap;
}

/* Active state for flip/toggle buttons */
.btn--active {
    background: var(--accent-bg) !important;
    border-color: var(--accent) !important;
    color: var(--accent-light) !important;
}

/* ── Scrollbar ────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 820px) {
    .panel--frames.active {
        grid-template-columns: 1fr;
    }
    .panel--effects.active {
        grid-template-columns: 1fr;
    }
    .output { flex-direction: column; }
    .effects-grid { grid-template-columns: repeat(auto-fill, minmax(110px, 1fr)); }
}

@media (max-width: 500px) {
    .app { padding: 12px 10px 40px; }
    .header__title { font-size: 1.4rem; }
    .tabs { flex-direction: column; }
    .tabs__btn { justify-content: center; }
}