:root {
    --bg-color: #F9F9F8;
    --sidebar-bg: #FFFFFF;
    --text-main: #1A1A1A;
    --text-muted: #757575;
    --accent-color: #2C2C2C;
    --border-color: #EAEAEA;
    --hover-color: #F4F4F2;
    --badge-bg: #F0F0EE;
    --card-bg: #FFFFFF;
    --scrollbar-thumb: #E0E0E0;
    --font-serif: 'Playfair Display', Georgia, serif;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

[data-theme="dark"] {
    --bg-color: #121212;
    --sidebar-bg: #1A1A1A;
    --text-main: #E0E0E0;
    --text-muted: #9A9A9A;
    --accent-color: #C5A880;
    --border-color: #2C2C2C;
    --hover-color: #262626;
    --badge-bg: #222222;
    --card-bg: #1A1A1A;
    --scrollbar-thumb: #333333;
}

* {
    box-sizing: border-box;
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

body, html {
    margin: 0;
    padding: 0;
    height: 100%;
    font-family: var(--font-sans);
    background-color: var(--bg-color);
    color: var(--text-main);
    display: flex;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
}

sidebar {
    width: 300px;
    min-width: 300px;
    background-color: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    height: 100vh;
    z-index: 10;
}

.sidebar-top {
    padding: 25px 20px 15px 20px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.sidebar-header {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: 1.5px;
    color: var(--text-main);
    text-transform: uppercase;
    cursor: pointer;
}

.sidebar-header span {
    display: block;
    font-family: var(--font-sans);
    font-size: 0.6rem;
    font-weight: 500;
    letter-spacing: 2px;
    color: var(--text-muted);
    margin-top: 3px;
}

.theme-toggle-btn {
    background: var(--badge-bg);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 0.9rem;
    transition: transform 0.2s ease, background 0.2s;
}

.theme-toggle-btn:hover {
    transform: scale(1.08);
}

.menu-container {
    flex: 1;
    overflow-y: auto;
    padding: 15px;
}

.menu-container::-webkit-scrollbar {
    width: 4px;
}
.menu-container::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 2px;
}

.group-title {
    padding: 15px 10px 8px 10px;
    font-size: 0.65rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1.5px;
}

.group-title:first-child {
    padding-top: 5px;
}

.sub-items {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.sub-btn {
    background: transparent;
    border: none;
    color: var(--text-main);
    padding: 8px 10px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.84rem;
    font-weight: 400;
    text-align: left;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: all 0.2s ease;
    width: 100%;
}

.sub-btn:hover {
    background-color: var(--hover-color);
    padding-left: 14px;
}

.sub-btn.active {
    background-color: var(--hover-color);
    font-weight: 500;
}

.sub-info {
    display: flex;
    align-items: center;
    gap: 8px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.thumb-icon {
    font-size: 0.9rem;
    opacity: 0.7;
    width: 16px;
    text-align: center;
}

.click-badge {
    background: var(--badge-bg);
    color: var(--text-muted);
    font-size: 0.65rem;
    font-weight: 500;
    padding: 2px 6px;
    border-radius: 10px;
}

.sub-btn:hover .click-badge {
    color: var(--text-main);
}

.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-color);
    height: 100vh;
    overflow: hidden;
    position: relative;
}

.welcome-screen {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 40px;
    overflow-y: auto;
}

.welcome-screen h1 {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 400;
    color: var(--text-main);
    margin: 0 0 15px 0;
    letter-spacing: -0.5px;
}

.welcome-screen p {
    color: var(--text-muted);
    max-width: 520px;
    font-size: 0.95rem;
    line-height: 1.7;
    margin: 0 0 35px 0;
    font-weight: 300;
}

.stats-box {
    display: flex;
    gap: 20px;
}

.stat-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 18px 30px;
    border-radius: 8px;
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--text-muted);
    box-shadow: 0 4px 12px rgba(0,0,0,0.02);
}

.stat-card span {
    display: block;
    font-family: var(--font-serif);
    font-size: 1.6rem;
    font-weight: 400;
    color: var(--text-main);
    margin-top: 6px;
    letter-spacing: 0;
}

.content-frame {
    display: none;
    width: 100%;
    height: 100%;
    border: none;
    background: #ffffff;
}

.thumb-img {
    width: 26px;
    height: 26px;
    border-radius: 4px;
    object-fit: cover;
    display: block;
}