/* 1. Base Variables & Reset */
:root {
    --bg-color: #f2f2f2;
    /* Pale gray background */
    --container-bg: #ffffff;
    /* Paper white */
    --border-color: #dcdcdc;
    /* Subtler border */
    --border-strong: #ccc;
    /* Main container border */
    --text-main: #222222;
    /* Deep gray/black */
    --text-sub: #555555;
    /* Secondary text */
    --accent-color: #2c3e50;
    --gap-base: 30px;
    --gap-small: 15px;
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

body,
html {
    margin: 0;
    padding: 0;
    height: 100%;
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: "Helvetica Neue", Helvetica, "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
}

/* 2. Main Container */
.container {
    max-width: 1080px;
    margin: 30px auto;
    padding: 40px;
    background-color: var(--container-bg);
    border: 1px solid var(--border-strong);
    border-radius: 4px;
    display: flex;
    flex-direction: column;
    gap: var(--gap-base);
}

/* 3. Generic Box Component */
.box {
    background-color: #fff;
    border: 1px solid var(--border-color);
    border-radius: 2px;
    padding: 20px;
    color: var(--text-sub);
    font-size: 1rem;
    line-height: 1.6;
    box-shadow: none;
    /* Explicitly remove shadow */
    transition: border-color 0.2s, background-color 0.2s;
}

.box:hover {
    background-color: #fafafa;
    border-color: #999;
}

/* 4. Header Section */
/* Overrides .box styles where necessary */
.header {
    border: none;
    border-bottom: 2px solid var(--text-main);
    border-radius: 0;
    padding: 0 0 10px 0;
    background-color: transparent;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

/* Reset hover effect for header specific parts if needed, 
   or allow it if it feels interactive. 
   Usually headers don't strictly need the .box hover effect. */
.header:hover {
    background-color: transparent;
    border-color: var(--text-main);
}

.header-content {
    display: flex;
    flex-direction: column;
}

#title {
    font-size: 2rem;
    margin: 0;
}

#description {
    display: inline-block;
    font-size: 0.6rem;
    margin: 0;
}

.header-nav {
    flex-grow: 1;
}

.header-nav ul {
    list-style: none;
    display: flex;
    gap: 10px;
    justify-content: space-around;
    width: 85%;
    margin: 0 auto;
}

.header-nav a {
    text-decoration: none;
    color: var(--text-main);
}

/* 5. Main Content Area */
.main-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--gap-base);
}

/* Content Left Overrides */
.content-left {
    border: none;
    padding: 0;
    font-size: 1.1em;
    background-color: transparent;
}

.content-left:hover {
    background-color: transparent;
    border-color: transparent;
}

/* Sidebar Overrides */
.sidebar-right {
    display: flex;
    flex-direction: column;
    gap: var(--gap-small);
}

.sidebar-item {
    flex: 1;
    min-height: 180px;
    background-color: #f9f9f9;
    border: 1px solid #e0e0e0;
}

/* 6. Footer */
.footer {
    border: none;
    border-top: 1px dashed #ccc;
    border-radius: 0;
    margin-top: 20px;
    padding-top: 20px;
    text-align: center;
    font-size: 0.9em;
    color: #888;
    background-color: transparent;
}

.footer:hover {
    background-color: transparent;
    border-color: transparent;
    border-top-color: #ccc;
}

.hide {
    display: none;
}

/* 7. Responsive Design */
@media (max-width: 768px) {
    .container {
        margin: 0;
        border: none;
        padding: 20px;
        width: 100%;
    }

    .main-content {
        grid-template-columns: 1fr;
    }

    .header {
        font-size: 1.2rem;
        flex-wrap: wrap;
        /* Safety for small screens */
    }

    .sidebar-right {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 10px;
    }

    .sidebar-item {
        flex: 1;
        min-width: 200px;
        min-height: 150px;
    }
}