:root {
    --bg-color: #0b0f19;
    --card-bg: #111827;
    --border-color: #1f2937;
    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --accent-primary: #3b82f6;
    --accent-primary-hover: #2563eb;
    --accent-success: #10b981;
    --focus-ring: rgba(59, 130, 246, 0.5);
    --accent-warning: #f59e0b;
    --accent-error: #ef4444;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    margin: 0;
    padding: 40px 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    box-sizing: border-box;
}

.container {
    max-width: 640px;
    width: 100%;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 30px;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
    box-sizing: border-box;
}

.header {
    text-align: center;
    margin-bottom: 25px;
}

.header h3 {
    margin: 0 0 8px 0;
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(to right, #60a5fa, #3b82f6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.header p {
    margin: 0;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.dropzone {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 35px 20px;
    text-align: center;
    background-color: rgba(31, 41, 55, 0.2);
    cursor: pointer;
    transition: border-color 0.2s, background-color 0.2s;
    margin-bottom: 20px;
    position: relative;
}

.dropzone:hover, .dropzone.dragover {
    border-color: var(--accent-primary);
    background-color: rgba(59, 130, 246, 0.05);
}

.dropzone input[type="file"] {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    opacity: 0;
    cursor: pointer;
}

.dropzone-icon {
    font-size: 2.2rem;
    margin-bottom: 10px;
}

.file-info {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.file-info .active-file {
    color: var(--text-primary);
    font-weight: 600;
    margin-top: 5px;
}

.progress-container {
    width: 100%;
    height: 6px;
    background-color: var(--border-color);
    border-radius: 3px;
    margin: 20px 0;
    overflow: hidden;
    display: none;
}

.progress-bar {
    width: 0%;
    height: 100%;
    background: linear-gradient(90deg, var(--accent-primary) 0%, var(--accent-success) 100%);
    transition: width 0.15s ease-out;
}

.status-msg {
    background-color: rgba(31, 41, 55, 0.4);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 12px;
    font-size: 0.85rem;
    text-align: center;
    margin-bottom: 20px;
    display: none;
    line-height: 1.4;
}

.input-group {
    margin-bottom: 15px;
}

.input-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 6px;
    color: var(--text-secondary);
}

.input-group input {
    width: 100%;
    background-color: rgba(17, 24, 39, 0.8);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 12px;
    color: var(--text-primary);
    font-size: 1rem;
    box-sizing: border-box;
    transition: border-color 0.15s, box-shadow 0.15s;
}

.input-group input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--focus-ring);
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 25px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    user-select: none;
    cursor: pointer;
}

.checkbox-group input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--accent-primary);
    cursor: pointer;
}

.btn-group {
    display: grid;
    grid-template-columns: 1fr;
}

button {
    padding: 12px 24px;
    font-size: 0.95rem;
    font-weight: 600;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.15s, transform 0.1s, box-shadow 0.15s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

button:active {
    transform: scale(0.98);
}

.btn-encrypt {
    background: linear-gradient(135deg, #2563eb 0%, #3b82f6 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
}

.btn-encrypt:hover {
    background: linear-gradient(135deg, #1d4ed8 0%, #2563eb 100%);
    box-shadow: 0 6px 16px rgba(59, 130, 246, 0.4);
}

/* ==================== 紧凑型列表式预览布局 ==================== */
.selected-files-container {
    background-color: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 15px;
    display: none;
    max-height: 550px; /* 略微调高，适应更大的默认预览 */
    overflow-y: auto;
}

.selected-files-title {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 12px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 5px;
}

/* 列表行大卡片 */
.preview-card {
    display: flex;
    align-items: center;
    background-color: rgba(0, 0, 0, 0.4);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 12px;
    padding: 12px;
    gap: 18px;
    box-sizing: border-box;
}

.preview-card:last-child {
    margin-bottom: 0;
}

/* 左侧：物理固定分辨率的多媒体容器（默认大小调整为 240x180） */
.preview-media-wrapper {
    width: 240px;
    height: 180px;
    background-color: #0b0f19;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    flex-shrink: 0;
    transition: width 0.2s ease-out, height 0.2s ease-out; /* 缩放过渡平滑动效 */
}

.preview-media-wrapper img,
.preview-media-wrapper video {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.preview-media-wrapper audio {
    width: 90%;
}

/* 右侧：信息与控制面板 */
.preview-info-panel {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    gap: 10px;
    min-width: 0;
}

.preview-file-name {
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--text-primary);
    word-break: break-all;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.preview-file-meta {
    font-size: 0.78rem;
    color: var(--text-secondary);
}

/* 缩放控制键组（强制隔离全局大 Button 属性） */
.zoom-btn-group {
    display: flex;
    gap: 8px;
}

.zoom-btn {
    width: auto !important;
    padding: 6px 12px !important;
    font-size: 0.75rem !important;
    margin-bottom: 0 !important;
    border-radius: 4px !important;
    background-color: rgba(255, 255, 255, 0.05) !important;
    color: var(--text-primary) !important;
    border: 1px solid var(--border-color) !important;
    cursor: pointer;
    display: inline-flex !important;
    align-items: center;
    justify-content: center;
}

.zoom-btn:hover {
    background-color: rgba(255, 255, 255, 0.15) !important;
}

.btn-remove-file {
    background-color: var(--accent-error);
    color: white;
    border: none;
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.75rem;
    align-self: flex-start;
    transition: background-color 0.15s;
}

.btn-remove-file:hover {
    background-color: #dc2626;
}