:root {
    --primary-color: #6366F1;
    --primary-hover: #4F46E5;
    --primary-light: #EEF2FF;
    --primary-glow: rgba(99, 102, 241, 0.15);
    --accent-color: #8B5CF6;
    --text-primary: #0F172A;
    --text-secondary: #475569;
    --text-muted: #94A3B8;
    --border-color: #E2E8F0;
    --border-light: #F1F5F9;
    --bg-white: #FFFFFF;
    --danger-color: #EF4444;
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-xl: 20px;
    --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    --font-sans: system-ui, -apple-system, 'Segoe UI', Roboto, 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'WenQuanYi Micro Hei', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    background: #0F172A;
    color: var(--text-primary);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow: hidden;
}

.cover-page {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.cover-bg {
    position: fixed;
    inset: 0;
    z-index: 0;
    overflow: hidden;
}

.cover-bg-grid {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(99, 102, 241, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99, 102, 241, 0.03) 1px, transparent 1px);
    background-size: 60px 60px;
}

.cover-bg-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.5;
    animation: orbFloat 20s ease-in-out infinite;
}

.cover-bg-orb-1 {
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.3), transparent 70%);
    top: -10%;
    right: -5%;
    animation-delay: 0s;
}

.cover-bg-orb-2 {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.25), transparent 70%);
    bottom: -10%;
    left: -5%;
    animation-delay: -7s;
}

.cover-bg-orb-3 {
    width: 350px;
    height: 350px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.2), transparent 70%);
    top: 40%;
    left: 50%;
    animation-delay: -14s;
}

@keyframes orbFloat {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(30px, -40px) scale(1.05); }
    50% { transform: translate(-20px, 20px) scale(0.95); }
    75% { transform: translate(15px, 35px) scale(1.02); }
}

.cover-content {
    position: relative;
    z-index: 1;
    text-align: center;
    padding: 40px 24px;
    max-width: 520px;
    width: 100%;
    animation: contentFadeIn 0.8s ease-out;
}

@keyframes contentFadeIn {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

.cover-brand {
    margin-bottom: 48px;
}

.cover-logo {
    margin-bottom: 24px;
    animation: logoFloat 6s ease-in-out infinite;
}

@keyframes logoFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

.cover-logo-icon {
    width: 72px;
    height: 72px;
    color: var(--primary-color);
    filter: drop-shadow(0 4px 20px rgba(99, 102, 241, 0.4));
}

.cover-title {
    font-size: 52px;
    font-weight: 800;
    letter-spacing: 0.06em;
    background: linear-gradient(135deg, #FFFFFF 0%, #C7D2FE 50%, #818CF8 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 12px;
    line-height: 1.2;
}

.cover-subtitle {
    font-size: 16px;
    color: rgba(148, 163, 184, 0.9);
    letter-spacing: 0.15em;
    font-weight: 400;
}

.cover-features {
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin-bottom: 48px;
    text-align: left;
}

.cover-feature {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 16px 20px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(99, 102, 241, 0.1);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(8px);
    transition: all var(--transition-base);
    animation: featureSlideIn 0.6s ease-out backwards;
}

.cover-feature:nth-child(1) { animation-delay: 0.2s; }
.cover-feature:nth-child(2) { animation-delay: 0.35s; }
.cover-feature:nth-child(3) { animation-delay: 0.5s; }

@keyframes featureSlideIn {
    from { opacity: 0; transform: translateX(-20px); }
    to { opacity: 1; transform: translateX(0); }
}

.cover-feature:hover {
    background: rgba(255, 255, 255, 0.07);
    border-color: rgba(99, 102, 241, 0.25);
    transform: translateX(4px);
}

.cover-feature-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-md);
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.15), rgba(139, 92, 246, 0.1));
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    color: #818CF8;
}

.cover-feature-icon svg {
    width: 22px;
    height: 22px;
}

.cover-feature-text h3 {
    font-size: 14px;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.95);
    margin-bottom: 2px;
}

.cover-feature-text p {
    font-size: 12px;
    color: rgba(148, 163, 184, 0.8);
}

.cover-actions {
    display: flex;
    gap: 16px;
    margin-bottom: 32px;
    animation: actionsFadeIn 0.6s ease-out 0.65s backwards;
}

@keyframes actionsFadeIn {
    from { opacity: 0; transform: translateY(16px); }
    to { opacity: 1; transform: translateY(0); }
}

.cover-btn {
    flex: 1;
    padding: 14px 32px;
    border: none;
    border-radius: var(--radius-md);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    letter-spacing: 0.5px;
    font-family: var(--font-sans);
}

.cover-btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: white;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.35);
}

.cover-btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.45);
}

.cover-btn-primary:active {
    transform: translateY(0);
}

.cover-btn-secondary {
    background: rgba(255, 255, 255, 0.06);
    color: rgba(255, 255, 255, 0.9);
    border: 1.5px solid rgba(99, 102, 241, 0.3);
}

.cover-btn-secondary:hover {
    background: rgba(99, 102, 241, 0.1);
    border-color: rgba(99, 102, 241, 0.5);
    transform: translateY(-2px);
}

.cover-btn-full {
    width: 100%;
    padding: 13px;
    font-size: 15px;
}

.cover-footer {
    animation: footerFadeIn 0.6s ease-out 0.8s backwards;
}

@keyframes footerFadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.cover-footer p {
    font-size: 12px;
    color: rgba(148, 163, 184, 0.5);
}

.cover-auth-modal {
    position: fixed;
    inset: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(15, 23, 42, 0.7);
    backdrop-filter: blur(8px);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-smooth);
}

.cover-auth-modal.active {
    opacity: 1;
    visibility: visible;
}

.cover-auth-card {
    background: rgba(30, 41, 59, 0.95);
    border: 1px solid rgba(99, 102, 241, 0.15);
    border-radius: var(--radius-xl);
    width: 400px;
    max-width: 90vw;
    padding: 32px;
    transform: translateY(20px) scale(0.96);
    transition: transform var(--transition-smooth);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.4), 0 0 80px rgba(99, 102, 241, 0.08);
}

.cover-auth-modal.active .cover-auth-card {
    transform: translateY(0) scale(1);
}

.cover-auth-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 28px;
}

.cover-auth-header h2 {
    font-size: 22px;
    font-weight: 700;
    color: rgba(255, 255, 255, 0.95);
}

.cover-auth-close {
    width: 36px;
    height: 36px;
    border: none;
    background: rgba(255, 255, 255, 0.06);
    color: rgba(148, 163, 184, 0.8);
    border-radius: var(--radius-sm);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.cover-auth-close svg {
    width: 18px;
    height: 18px;
}

.cover-auth-close:hover {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.9);
}

.cover-auth-field {
    margin-bottom: 20px;
}

.cover-auth-field label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    color: rgba(148, 163, 184, 0.9);
    margin-bottom: 8px;
}

.cover-auth-field input {
    width: 100%;
    padding: 12px 16px;
    border: 1.5px solid rgba(99, 102, 241, 0.15);
    border-radius: var(--radius-sm);
    font-size: 14px;
    color: rgba(255, 255, 255, 0.95);
    background: rgba(255, 255, 255, 0.04);
    outline: none;
    transition: all var(--transition-base);
    font-family: var(--font-sans);
}

.cover-auth-field input::placeholder {
    color: rgba(148, 163, 184, 0.4);
}

.cover-auth-field input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
    background: rgba(255, 255, 255, 0.06);
}

.cover-auth-error {
    color: var(--danger-color);
    font-size: 13px;
    min-height: 20px;
    margin-bottom: 8px;
}

.cover-auth-switch {
    text-align: center;
    margin-top: 20px;
    font-size: 13px;
    color: rgba(148, 163, 184, 0.6);
}

.cover-auth-switch a {
    color: #818CF8;
    text-decoration: none;
    font-weight: 600;
    transition: color var(--transition-fast);
}

.cover-auth-switch a:hover {
    color: var(--primary-color);
}

.cover-page.transitioning {
    animation: pageTransition 0.6s ease-in forwards;
}

@keyframes pageTransition {
    0% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.02); filter: blur(2px); }
    100% { opacity: 0; transform: scale(1.05); filter: blur(6px); }
}

@media (max-width: 640px) {
    .cover-title {
        font-size: 38px;
    }

    .cover-subtitle {
        font-size: 14px;
        letter-spacing: 0.1em;
    }

    .cover-logo-icon {
        width: 56px;
        height: 56px;
    }

    .cover-features {
        gap: 12px;
    }

    .cover-feature {
        padding: 12px 16px;
    }

    .cover-feature-icon {
        width: 38px;
        height: 38px;
    }

    .cover-feature-icon svg {
        width: 18px;
        height: 18px;
    }

    .cover-btn {
        padding: 12px 24px;
        font-size: 14px;
    }

    .cover-auth-card {
        padding: 24px;
    }
}