:root {
    --brand: #165dff;
    --brand-600: #0d47d9;
    --ink-900: #0b1220;
    --ink-700: #2b3a55;
    --ink-500: #5b6b88;
    --ink-400: #7c8aa6;
    --ink-300: #a5b1c7;
    --surface: #ffffff;
    --surface-2: rgba(255, 255, 255, 0.8);
    --glass: rgba(255, 255, 255, 0.65);
    --line: #e5e9f2;
    --shadow-sm: 0 2px 10px rgba(13, 71, 217, 0.10);
    --shadow-md: 0 10px 30px rgba(13, 71, 217, 0.15);
    --shadow-lg: 0 25px 60px rgba(13, 71, 217, 0.20);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --blur: 12px;
    --gradient: radial-gradient(1000px 600px at 80% -10%, rgba(22,93,255,0.20) 0%, rgba(22,93,255,0.08) 30%, rgba(22,93,255,0.0) 60%), linear-gradient(180deg, #f6fbff 0%, #eaf5ff 100%);
    --accent-glow: 0 0 0 0 rgba(22,93,255,0.0);
    --transition-quick: 180ms cubic-bezier(.2,.7,.2,1);
    --transition-smooth: 420ms cubic-bezier(.2,.7,.2,1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Microsoft Yahei", sans-serif;
}

body {
    background: var(--gradient);
    min-height: 100vh;
    color: var(--ink-700);
    position: relative;
    overflow-x: hidden;
}

body::before,
body::after {
    content: "";
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 0;
}

body::before {
    background:
        radial-gradient(1200px 600px at 10% 10%, rgba(22,93,255,0.12), transparent 60%),
        radial-gradient(800px 400px at 90% 20%, rgba(22,93,255,0.10), transparent 60%);
    filter: blur(0.5px);
}

body::after {
    background-image:
        linear-gradient(rgba(22,93,255,0.07) 1px, transparent 1px),
        linear-gradient(90deg, rgba(22,93,255,0.07) 1px, transparent 1px);
    background-size: 28px 28px, 28px 28px;
    mask-image: radial-gradient(1000px 600px at 50% 0%, black, transparent 70%);
    opacity: 0.4;
}

.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 15px 5%;
    background: linear-gradient(180deg, rgba(255,255,255,0.8), rgba(255,255,255,0.55));
    backdrop-filter: saturate(160%) blur(10px);
    -webkit-backdrop-filter: saturate(160%) blur(10px);
    border-bottom: 1px solid rgba(22, 93, 255, 0.10);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 22px;
    font-weight: bold;
    color: var(--brand);
    letter-spacing: 0.2px;
}

.logo-icon {
    width: 36px;
    height: 36px;
    background: conic-gradient(from 120deg, #2d7bff, var(--brand), #4c8dff, var(--brand));
    border-radius: 10px;
    border: 1px solid rgba(22,93,255,0.25);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    box-shadow: 0 6px 16px rgba(22,93,255,0.35), inset 0 1px 0 rgba(255,255,255,0.35);
    position: relative;
    overflow: hidden;
    transition: transform var(--transition-quick), box-shadow var(--transition-quick), filter var(--transition-quick);
}

.logo-icon::after {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(60% 60% at 30% 20%, rgba(255,255,255,0.6), transparent 60%);
    opacity: 0.9;
    pointer-events: none;
}

.logo-icon .glyph {
    font-weight: 800;
    font-size: 18px;
    letter-spacing: 0.5px;
    text-shadow: 0 1px 0 rgba(0,0,0,0.15);
}

.logo:hover .logo-icon {
    transform: rotate(6deg) scale(1.02);
    box-shadow: 0 10px 24px rgba(22,93,255,0.42), inset 0 1px 0 rgba(255,255,255,0.35);
    filter: saturate(110%);
}

.brand-name {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-weight: 800;
    letter-spacing: 0.3px;
    color: var(--ink-900);
}

.brand-name .emph {
    background: linear-gradient(90deg, var(--brand), #2d7bff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.nav-links {
    display: flex;
    gap: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--ink-700);
    font-size: 16px;
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: color var(--transition-quick);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--brand);
}

.nav-links a::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -8px;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--brand), transparent);
    transform: scaleX(0);
    transform-origin: 50% 50%;
    transition: transform var(--transition-smooth);
}

.nav-links a:hover::after,
.nav-links a.active::after {
    transform: scaleX(1);
}

.nav-item {
    position: relative;
    display: inline-flex;
    align-items: center;
}

.has-submenu:hover > a,
.has-submenu:focus-within > a {
    color: var(--brand);
}

.has-submenu > a .caret {
    width: 12px;
    height: 12px;
    margin-left: 2px;
    transition: transform var(--transition-quick);
}

.has-submenu:hover > a .caret,
.has-submenu:focus-within > a .caret {
    transform: rotate(180deg);
}

.submenu {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    min-width: 340px;
    background: linear-gradient(180deg, rgba(255,255,255,0.95), rgba(255,255,255,0.86));
    backdrop-filter: blur(10px) saturate(140%);
    -webkit-backdrop-filter: blur(10px) saturate(140%);
    border: 1px solid rgba(22,93,255,0.12);
    border-radius: 12px;
    box-shadow: 0 18px 36px rgba(22,93,255,0.16);
    padding: 10px 10px 12px;
    display: grid;
    gap: 6px;
    opacity: 0;
    transform: translateY(6px);
    pointer-events: none;
    transition: opacity var(--transition-quick), transform var(--transition-quick), visibility var(--transition-quick);
    z-index: 200;
}

.has-submenu:hover .submenu,
.has-submenu:focus-within .submenu {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.submenu .menu-header {
    padding: 8px 12px 6px;
    color: var(--ink-500);
    font-size: 12px;
}

.submenu a {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    padding: 10px 12px;
    border-radius: 10px;
    color: var(--ink-700);
    text-decoration: none;
    border: 1px solid transparent;
    background: linear-gradient(180deg, rgba(255,255,255,0.9), rgba(255,255,255,0.82));
    transition: background var(--transition-quick), border-color var(--transition-quick), color var(--transition-quick), box-shadow var(--transition-quick);
}

.submenu .item-head {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.submenu .title {
    font-weight: 600;
    color: var(--ink-900);
}

.submenu .sub-label {
    font-size: 12px;
    color: var(--ink-400);
}

.submenu a:hover {
    border-color: rgba(22,93,255,0.25);
    box-shadow: 0 8px 22px rgba(22,93,255,0.18);
    background: linear-gradient(135deg, rgba(22,93,255,0.12), rgba(22,93,255,0.02));
    color: var(--brand);
}

.submenu a.free-highlight {
    border: 1.5px solid rgba(33, 193, 122, 0.35);
    position: relative;
    overflow: hidden;
}

.submenu a.free-highlight::before {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(33, 193, 122, 0.15), transparent);
    animation: shimmer 3s infinite;
}

@keyframes shimmer {
    0% { left: -100%; }
    100% { left: 100%; }
}

.submenu a.free-highlight .title {
    color: #21c17a;
    display: flex;
    align-items: center;
    gap: 6px;
}

.submenu a.free-highlight .free-badge {
    display: inline-flex;
    align-items: center;
    padding: 2px 6px;
    background: linear-gradient(135deg, #21c17a, #18a86b);
    color: white;
    border-radius: 4px;
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 0.3px;
    box-shadow: 0 2px 6px rgba(33, 193, 122, 0.3);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.submenu a.free-highlight:hover {
    background: linear-gradient(135deg, rgba(33, 193, 122, 0.18), rgba(33, 193, 122, 0.10));
    border-color: rgba(33, 193, 122, 0.5);
    box-shadow: 0 8px 20px rgba(33, 193, 122, 0.25);
    transform: translateY(-1px);
}

.submenu a.free-highlight .sub-label {
    color: #18a86b;
    font-weight: 500;
}

@media (max-width: 768px) {
    .submenu {
        display: none !important;
    }
}

.nav-icon {
    width: 16px;
    height: 16px;
    display: inline-block;
    color: currentColor;
}

.auth-buttons {
    display: flex;
    gap: 10px;
}

.btn {
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    border: none;
    cursor: pointer;
    font-size: 14px;
    transition: transform var(--transition-quick), box-shadow var(--transition-quick), background var(--transition-quick), color var(--transition-quick);
    position: relative;
    will-change: transform;
}

.btn-login {
    background: linear-gradient(180deg, #ffffff, #f6fbff);
    color: var(--brand);
    border: 1px solid rgba(22,93,255,0.22);
    box-shadow: 0 3px 10px rgba(22,93,255,0.10);
}

.btn-login:hover {
    transform: translateY(-1px);
    box-shadow: 0 8px 22px rgba(22,93,255,0.18);
}

.btn-register {
    background: linear-gradient(135deg, var(--brand), #2d7bff);
    color: #fff;
    box-shadow: 0 10px 24px rgba(22,93,255,0.35), var(--accent-glow);
}

.btn-register:hover {
    transform: translateY(-1px);
    box-shadow: 0 16px 34px rgba(22,93,255,0.45);
}

.site-footer {
    margin-top: 80px;
    padding: 40px 5% 30px;
    background: linear-gradient(180deg, rgba(255,255,255,0.92), rgba(240,246,255,0.85));
    border-top: 1px solid rgba(22,93,255,0.12);
    box-shadow: 0 -10px 30px rgba(22,93,255,0.08);
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    gap: 24px;
    justify-content: space-between;
    align-items: center;
    color: var(--ink-500);
    font-size: 13px;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--ink-700);
}

.footer-brand .logo-icon {
    width: 32px;
    height: 32px;
}

.footer-links {
    display: flex;
    gap: 18px;
    flex-wrap: wrap;
    align-items: center;
}

.footer-links a {
    color: var(--ink-500);
    text-decoration: none;
    transition: color var(--transition-quick);
}

.footer-links a:hover {
    color: var(--brand);
}

.footer-meta {
    display: flex;
    flex-direction: column;
    gap: 4px;
    font-size: 12px;
    color: var(--ink-400);
}

.reveal {
    opacity: 0;
    transform: translateY(18px) scale(0.98);
    filter: saturate(80%);
    transition: opacity 600ms cubic-bezier(.2,.7,.2,1), transform 600ms cubic-bezier(.2,.7,.2,1), filter 600ms cubic-bezier(.2,.7,.2,1);
}

.revealed {
    opacity: 1;
    transform: translateY(0) scale(1);
    filter: saturate(110%);
}