:root {
    --bg-color: #f8fafc;
    --text-color: #64748b;
    --border-color: #e2e8f0;
    --card-bg: #f8fafc;
    --highlight-color: #3b82f6;
    --highlight-text: #ffffff;
    --drag-border: #cbd5e1;
    --drag-text: #334155;
    --drag-hint: #94a3b8;
    --brand-color: #1e293b;
    --top-bar-border: #f1f5f9;
}

[data-theme="dark"] {
    --bg-color: #18181b;
    --text-color: #a1a1aa;
    --border-color: #27272a;
    --card-bg: #27272a;
    --drag-border: #3f3f46;
    --drag-text: #e4e4e7;
    --drag-hint: #94a3b8;
    --brand-color: #e4e4e7;
    --top-bar-border: #3f3f46;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: "Segoe UI", system-ui, sans-serif;
    user-select: none;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition: background-color 0.3s, color 0.3s;
}

/* Top Bar */
#top-bar {
    height: 64px;
    display: flex;
    align-items: center;
    padding: 0 24px;
    border-bottom: 1px solid var(--top-bar-border);
    background-color: var(--bg-color);
    flex-shrink: 0;
}

#brand {
    font-size: 18px;
    font-weight: 700;
    color: var(--brand-color);
    margin-right: auto;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 20px;
}

label.checkbox-container {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    font-size: 14px;
}

input[type="checkbox"] {
    accent-color: var(--highlight-color);
    width: 16px;
    height: 16px;
}

#theme-btn {
    background: transparent;
    border: none;
    font-size: 18px;
    cursor: pointer;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
}

#theme-btn:hover {
    background-color: rgba(128, 128, 128, 0.1);
}

/* Tabs */
#tabs-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 24px;
    overflow: hidden;
}

#tab-header {
    display: flex;
    margin-bottom: 0;
}

.tab-btn {
    padding: 10px 20px;
    min-width: 132px;
    background-color: var(--border-color);
    color: var(--text-color);
    border: none;
    border-top-left-radius: 4px;
    border-top-right-radius: 4px;
    margin-right: 4px;
    cursor: pointer;
    font-weight: 600;
    font-size: 15px;
    transition: background-color 0.2s;
}

.tab-btn.active {
    background-color: var(--highlight-color);
    color: var(--highlight-text);
}

.tab-content {
    display: none;
    flex: 1;
    background-color: var(--bg-color);
    padding-top: 24px;
    height: 100%;
}

.tab-content.active {
    display: flex;
    flex-direction: column;
}

/* Grid Layouts */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    height: 100%;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(2, 1fr);
    gap: 16px;
    height: 100%;
}

/* Drag Area */
.drag-area {
    border: 2px dashed var(--drag-border);
    border-radius: 12px;
    background-color: var(--card-bg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    cursor: default;
    min-height: 200px;
    position: relative;
}

.drag-area:hover, .drag-area.drag-over {
    border-color: var(--highlight-color);
    border-style: solid;
    background-color: rgba(59, 130, 246, 0.05);
}

.drag-area[data-action="format"]:hover { border-color: #10b981; }
.drag-area[data-action="rename"]:hover { border-color: #8b5cf6; }
.drag-area[data-action^="stretch"]:hover { border-color: #f59e0b; }

.drag-title {
    font-size: 20px;
    font-weight: 700;
    color: var(--drag-text);
    margin-bottom: 4px;
    pointer-events: none;
}

.drag-hint {
    font-size: 12px;
    color: var(--drag-hint);
    pointer-events: none;
}

/* Status Bar */
#status-bar {
    height: 32px;
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    padding: 0 12px;
    font-size: 12px;
    background-color: var(--bg-color);
    flex-shrink: 0;
}

/* Utility */
.hidden { display: none !important; }

/* Permission Warning */
#perm-warning {
    position: fixed;
    top: 70px;
    right: 20px;
    background: #f59e0b;
    color: white;
    padding: 10px 16px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    font-size: 14px;
    z-index: 1000;
    display: none;
    align-items: center;
    gap: 10px;
    cursor: pointer;
}