.scale-container {
    max-width: 800px;
    margin: 1rem auto;
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--preview-bg);
}

.screen {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.hidden {
    display: none !important;
}

/* Calibration UI */
.instruction {
    color: var(--text-color);
    font-size: 1rem;
    line-height: 1.5;
    text-align: center;
    margin-bottom: 0.5rem;
}

.card-stage {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem 0;
    overflow: hidden;
}

.cal-card {
    background-color: var(--accent-color);
    border-radius: 12px;
    /* Aspect ratio of a standard CR80 credit card */
    aspect-ratio: 1.5857; 
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    color: #fff;
    font-weight: 600;
    font-size: 0.9rem;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    /* Initial physical estimate mapped in JS */
    width: 320px; 
}

.slider-container {
    display: flex;
    align-items: center;
    gap: 1rem;
    max-width: 500px;
    width: 100%;
    margin: 0 auto;
}

#cal-slider {
    flex-grow: 1;
    cursor: ew-resize;
}

/* Upload UI */
.header-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

.drop-zone {
    padding: 4rem 2rem;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-color);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 1rem;
}

.drop-zone:hover, .drop-zone.dragover {
    background-color: var(--preview-bg);
    border-color: var(--accent-color);
}

.drop-zone-icon {
    font-size: 3rem;
    pointer-events: none;
}

.drop-zone-text {
    color: var(--text-color);
    font-size: 1.1rem;
    font-weight: 500;
    pointer-events: none;
    line-height: 1.5;
}

.dpi-fallback {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    color: var(--label-text);
    font-size: 0.9rem;
}

.dpi-fallback select {
    padding: 0.3rem;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-color);
    color: var(--text-color);
}

/* Viewer UI */
.file-info-label {
    color: var(--text-color);
    font-weight: 500;
}

.viewer-window {
    width: 100%;
    height: 65vh;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    overflow: auto; /* Enable panning of large 1:1 items */
    position: relative;
    box-shadow: inset 0 2px 8px rgba(0,0,0,0.05);
}

.render-wrapper {
    display: inline-block;
    background-color: #fff; /* Ensure document background is white */
    box-shadow: 2px 2px 10px rgba(0,0,0,0.2);
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 4px;
    background-color: var(--accent-color);
    color: #fff;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: opacity 0.2s;
    width: 100%;
    max-width: 300px;
    margin: 0 auto;
}

.btn:hover {
    opacity: 0.85;
}

.text-btn {
    background: none;
    border: none;
    color: var(--accent-color);
    cursor: pointer;
    font-weight: 600;
    font-size: 0.9rem;
}

.text-btn:hover {
    text-decoration: underline;
}

body.dark-mode .btn, body.dark-mode .text-btn {
    color: var(--bg-color-dark);
}
body.dark-mode .text-btn {
    color: var(--accent-color-dark);
}