:root {
    --background-light: #f5f5f5;
    --background-dark: #1e1e1e;
    --text-light: #333;
    --text-dark: #f5f5f5;
    --accent-light: #0078d4;
    --accent-dark: #1e90ff;
    --border-color-light: #ccc;
    --border-color-dark: #555;
}

body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: var(--background-light);
    color: var(--text-light);
    transition: background-color 0.3s, color 0.3s;
}

body.dark-mode {
    background-color: var(--background-dark);
    color: var(--text-dark);
}

.container {
    max-width: 800px;
    margin: 20px auto;
    padding: 20px;
    background-color: var(--background-light);
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.07);
    transition: background-color 0.3s, box-shadow 0.3s;
}

body.dark-mode .container {
    background-color: #2c2c2c;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

h1 {
    margin: 0 0 10px 0;
    font-size: 2em;
}

.dark-mode-toggle {
    display: inline-flex;
    align-items: center;
    font-size: 1em;
    cursor: pointer;
    float: right;
}

.dark-mode-toggle input {
    margin-left: 8px;
    transform: scale(1.2);
}

.version-label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

.version-select {
    width: 100%;
    padding: 10px;
    font-size: 1em;
    border: 1px solid var(--border-color-light);
    border-radius: 5px;
    background-color: var(--background-light);
    color: var(--text-light);
    margin-bottom: 15px;
    transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

body.dark-mode .version-select {
    background-color: #3a3a3a;
    color: var(--text-dark);
    border-color: var(--border-color-dark);
}

.file-input {
    display: block;
    margin-bottom: 10px;
}

.file-hint {
    font-size: 0.9em;
    color: #d00;
    margin: 0 0 10px 0;
    visibility: visible;
    opacity: 1;
    transition: opacity 0.3s;
}

.file-list {
    list-style: none;
    padding: 0;
    margin: 0 0 15px 0;
}

.file-item {
    margin: 5px 0;
    padding: 10px;
    border: 1px solid var(--border-color-light);
    border-radius: 5px;
    background-color: #fafafa;
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: grab;
    transition: background-color 0.3s, border-color 0.3s;
}

body.dark-mode .file-item {
    background-color: #3c3c3c;
    border-color: var(--border-color-dark);
}

.file-item.dragging {
    opacity: 0.5;
}

.file-item.over {
    border: 1px dashed var(--accent-light);
}

.file-item img {
    width: 50px;
    height: 50px;
    margin-right: 10px;
    border-radius: 5px;
    object-fit: cover;
}

.file-item .remove-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2em;
    color: #900;
}

body.dark-mode .file-item .remove-btn {
    color: #ff6666;
}

.combine-button {
    display: block;
    width: 100%;
    padding: 15px;
    font-size: 1.2em;
    color: #fff;
    background-color: var(--accent-dark);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s, opacity 0.3s;
}

.combine-button:disabled {
    background-color: #777;
    cursor: not-allowed;
    opacity: 0.6;
}

footer {
    text-align: center;
    margin-top: 20px;
    font-size: 0.9em;
    color: #888;
}

body.dark-mode footer {
    color: #bbb;
}