:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #1e293b;
    --bg-color: #ffffff;
    --surface-color: #f8fafc;
    --text-main: #0f172a;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --transition-speed: 0.3s;
    --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --bg-color: #0f172a;
    --surface-color: #1e293b;
    --text-main: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.3);
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
    font-family: var(--font-stack);
}

/* 确保导航栏内所有元素使用一致的字体 */
.header * {
    font-family: var(--font-stack);
}

[data-theme="dark"] .header {
    background-color: rgba(15, 23, 42, 0.9);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
    letter-spacing: -0.5px;
}

.back-link {
    padding: 8px 16px;
    background: linear-gradient(135deg, #6c757d, #495057);
    color: white;
    text-decoration: none;
    border-radius: 20px;
    font-weight: 600;
    font-size: 14px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(108, 117, 125, 0.3);
}

.back-link:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(108, 117, 125, 0.4);
}

.desktop-nav {
    display: none;
}

@media (min-width: 768px) {
    .desktop-nav {
        display: flex;
        gap: var(--space-md);
    }
}

.nav-link {
    position: relative;
    font-weight: 500;
    color: var(--text-main) !important;
    padding: 0.5rem 0;
    font-size: 1rem !important;
    line-height: 1.6 !important;
    text-decoration: none !important;
    text-shadow: none !important;
    letter-spacing: normal !important;
    background: transparent !important;
    border-radius: 0 !important;
    font-family: var(--font-stack) !important;
}

.nav-link:hover {
    color: var(--text-main) !important;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width var(--transition-speed);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-main);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-speed);
}

.theme-toggle:hover {
    background-color: var(--surface-color);
}

.hamburger {
    display: flex;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
    z-index: 1002;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--text-main);
    border-radius: 2px;
    transition: all var(--transition-speed);
}

@media (min-width: 768px) {
    .hamburger {
        display: none;
    }
}

.mobile-nav-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-speed), visibility var(--transition-speed);
}

.mobile-nav-overlay.open {
    opacity: 1;
    visibility: visible;
}

.mobile-nav-sidebar {
    position: fixed;
    top: 0;
    left: -300px;
    width: 280px;
    height: 100%;
    background-color: var(--bg-color);
    z-index: 1001;
    padding: 2rem;
    transition: left var(--transition-speed) var(--ease-in-out);
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
}

.mobile-nav-overlay.open .mobile-nav-sidebar {
    left: 0;
}

.mobile-nav-list {
    margin-top: 4rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.mobile-nav-item {
    opacity: 0;
    transform: translateX(-20px);
    transition: all var(--transition-speed);
}

.mobile-nav-overlay.open .mobile-nav-item {
    opacity: 1;
    transform: translateX(0);
}

.mobile-nav-overlay.open .mobile-nav-item:nth-child(1) { transition-delay: 0.1s; }
.mobile-nav-overlay.open .mobile-nav-item:nth-child(2) { transition-delay: 0.2s; }
.mobile-nav-overlay.open .mobile-nav-item:nth-child(3) { transition-delay: 0.3s; }
.mobile-nav-overlay.open .mobile-nav-item:nth-child(4) { transition-delay: 0.4s; }
.mobile-nav-overlay.open .mobile-nav-item:nth-child(5) { transition-delay: 0.5s; }