/* 全局基础样式 */
body {
    margin: 0;
    padding: 0;
    font-family: "Inter", "Segoe UI", Arial;
    background: var(--bg);
    color: var(--text);
    transition: background 0.25s, color 0.25s;
}

/* 浅色/深色模式变量 */
:root {
    --bg: #f6f8fa;
    --text: #222;
    --card: #ffffff;
    --border: #e2e2e2;
    --nav-bg: rgba(255,255,255,0.8);
    --nav-shadow: rgba(0,0,0,0.1);
    --btn-bg: #e9e9e9;
    --btn-text: #222;
}

.dark {
    --bg: #0d1117;
    --text: #e6edf3;
    --card: #161b22;
    --border: #272c33;
    --nav-bg: rgba(22,27,34,0.9);
    --nav-shadow: rgba(0,0,0,0.4);
    --btn-bg: #21262d;
    --btn-text: #e6edf3;
}

/* 导航栏 */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 28px;
    background: var(--nav-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    box-shadow: 0 3px 12px var(--nav-shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-title {
    font-size: 18px;
    font-weight: 600;
}

/* 按钮样式统一 */
.nav-buttons {
    display: flex;
    gap: 15px;
}

.nav-btn {
    padding: 8px 18px;
    border-radius: 12px;
    border: 1px solid var(--border);
    background: var(--btn-bg);
    color: var(--btn-text);
    cursor: pointer;
    text-decoration: none;
    transition: 0.25s;
    font-size: 14px;
    font-weight: 500;
}

.nav-btn:hover {
    filter: brightness(1.12);
}

/* 页面布局 */
.container {
    max-width: 900px;
    margin: 50px auto;
    padding: 0 20px;
}

/* 404 页面 */
.notfound-box {
    text-align: center;
    margin-top: 80px;
}

.notfound-code {
    font-size: 120px;
    font-weight: 800;
    color: #ff4757;
    letter-spacing: -5px;
}

.notfound-text {
    font-size: 22px;
    margin-bottom: 25px;
    opacity: 0.8;
}

.notfound-back {
    padding: 10px 25px;
    background: var(--btn-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    color: var(--btn-text);
    cursor: pointer;
    text-decoration: none;
    transition: 0.25s;
}

.notfound-back:hover {
    filter: brightness(1.15);
}

.card {
  background: var(--card);
  padding: 20px;
  border-radius: 20px;
  backdrop-filter: blur(10px);
  margin-bottom: 20px;
}