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

:root {
    --color-primary: #6366f1;
    --color-secondary: #8b5cf6;
    --color-accent: #06b6d4;
    --color-bg-dark: #0f172a;
    --color-bg-card: rgba(30, 41, 59, 0.7);
    --color-text-primary: #f8fafc;
    --color-text-secondary: #94a3b8;
    --color-border: rgba(255, 255, 255, 0.1);
    --glow-primary: rgba(99, 102, 241, 0.5);
    --glow-accent: rgba(6, 182, 212, 0.5);
    
    --font-size-year: 6rem;
    --font-size-month-day: 4.5rem;
    --font-size-separator: 2.8rem;
    --font-size-weekday: 1.5rem;
    --font-size-lunar: 1.3rem;
    --font-size-time: 3.4rem;
    --spacing-main: 14px;
    --spacing-sub: 28px;
    
    --font-family-display: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'PingFang SC', 'Microsoft YaHei', sans-serif;
    --font-family-mono: 'SF Mono', 'Monaco', 'Consolas', ui-monospace, monospace;
}

html {
    font-size: 16px;
}

body {
    font-family: var(--font-family-display);
    overflow: hidden;
    background-color: var(--color-bg-dark);
    color: var(--color-text-primary);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

.bg-layer {
    position: fixed;
    inset: 0;
    z-index: 0;
}

.bg-image {
    position: absolute;
    inset: 0;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    opacity: 0.9;
    transition: opacity 1.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.bg-gradient {
    position: absolute;
    inset: 0;
    background: 
        radial-gradient(ellipse at 20% 30%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 70%, rgba(139, 92, 246, 0.1) 0%, transparent 50%);
}

.bg-particles {
    position: absolute;
    inset: 0;
}

.particle {
    position: absolute;
    width: 3px;
    height: 3px;
    background-color: rgba(255, 255, 255, 0.6);
    border-radius: 50%;
    animation: float 20s infinite;
    pointer-events: none;
}

@keyframes float {
    0%, 100% {
        transform: translate(0, 0) scale(1);
        opacity: 0;
    }
    10%, 90% {
        opacity: 1;
    }
    100% {
        transform: translate(var(--tx, 100px), var(--ty, 100px)) scale(0.5);
    }
}

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

.container {
    position: relative;
    width: 100vw;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1;
    padding: 20px;
}

.main-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 50px;
    padding: 40px;
    max-width: 900px;
    width: 100%;
}

.date-section {
    text-align: center;
    animation: fadeInDown 0.8s ease;
    position: relative;
    z-index: 10;
    text-shadow: 0 0 30px var(--glow-primary);
}

.date-main {
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: var(--spacing-main);
    margin-bottom: 12px;
    flex-wrap: wrap;
}

.date-year {
    font-size: var(--font-size-year);
    font-weight: 700;
    background: linear-gradient(135deg, #a5b4fc, #67e8f9);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -2px;
    text-shadow: 
        0 0 20px rgba(165, 180, 252, 0.6),
        0 0 40px rgba(103, 232, 249, 0.4);
    transition: font-size 0.3s ease;
}

.date-sep {
    font-size: var(--font-size-separator);
    color: #cbd5e1;
    font-weight: 300;
    text-shadow: 0 0 15px var(--glow-primary);
    transition: font-size 0.3s ease;
}

.date-month,
.date-day {
    font-size: var(--font-size-month-day);
    font-weight: 600;
    color: var(--color-text-primary);
    letter-spacing: -1px;
    text-shadow: 
        0 0 15px rgba(248, 250, 252, 0.4),
        0 0 30px var(--glow-primary);
    transition: font-size 0.3s ease;
}

.date-sub {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sub);
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.date-weekday {
    font-size: var(--font-size-weekday);
    color: var(--color-accent);
    font-weight: 500;
    padding: 6px 16px;
    background-color: rgba(6, 182, 212, 0.2);
    border-radius: 20px;
    border: 1px solid rgba(6, 182, 212, 0.5);
    box-shadow: 
        0 0 15px var(--glow-accent),
        inset 0 0 15px rgba(6, 182, 212, 0.1);
    transition: all 0.3s ease;
}

.date-lunar {
    font-size: var(--font-size-lunar);
    color: #e2e8f0;
    text-shadow: 0 0 10px var(--glow-primary);
    transition: font-size 0.3s ease;
}

.date-time {
    font-size: var(--font-size-time);
    font-weight: 500;
    color: #ffffff;
    font-family: var(--font-family-mono);
    letter-spacing: 8px;
    text-shadow: 
        0 0 25px rgba(165, 180, 252, 0.9),
        0 0 50px var(--glow-primary),
        0 0 80px var(--glow-accent),
        0 0 100px rgba(6, 182, 212, 0.3);
    margin-top: 8px;
    transition: all 0.3s ease;
    white-space: nowrap;
}

.time-format-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 12px;
    background-color: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 20px;
    color: #ffffff;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
    z-index: 100;
}

.time-format-toggle:hover {
    background-color: rgba(255, 255, 255, 0.2);
    border-color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: 0 4px 20px var(--glow-primary);
}

.time-format-toggle:active {
    transform: translateY(0);
}

.time-format-toggle svg {
    width: 16px;
    height: 16px;
    transition: transform 0.3s ease;
}

.time-format-toggle:hover svg {
    transform: rotate(15deg);
}

.time-format-toggle #format-label {
    font-family: var(--font-family-mono);
    letter-spacing: 1px;
}

@media (min-width: 1200px) {
    :root {
        --font-size-year: 8rem;
        --font-size-month-day: 6rem;
        --font-size-separator: 3.8rem;
        --font-size-time: 4.5rem;
    }
    
    .main-content {
        max-width: 1400px;
        gap: 100px;
        padding: 100px;
    }
    
    .date-time {
        letter-spacing: 15px;
    }
}

@media (min-width: 1024px) and (max-width: 1199px) {
    :root {
        --font-size-year: 7rem;
        --font-size-month-day: 5.2rem;
        --font-size-separator: 3.4rem;
        --font-size-time: 4rem;
    }
    
    .main-content {
        max-width: 1100px;
        gap: 85px;
    }
}

@media (max-width: 768px) {
    :root {
        --font-size-year: 5.2rem;
        --font-size-month-day: 4rem;
        --font-size-separator: 2.5rem;
        --font-size-weekday: 1.5rem;
        --font-size-lunar: 1.3rem;
        --font-size-time: 3rem;
        --spacing-main: 14px;
        --spacing-sub: 28px;
    }
    
    .main-content {
        gap: 60px;
        padding: 50px 35px;
    }
    
    .date-time {
        letter-spacing: 10px;
    }
    
    .date-weekday {
        padding: 10px 22px;
    }
    
    .time-format-toggle {
        top: 15px;
        right: 15px;
        padding: 12px 16px;
        font-size: 1.1rem;
    }
    
    .time-format-toggle svg {
        width: 20px;
        height: 20px;
    }
}

@media (max-width: 600px) {
    :root {
        --font-size-year: 4.5rem;
        --font-size-month-day: 3.5rem;
        --font-size-separator: 2.2rem;
        --font-size-weekday: 1.35rem;
        --font-size-lunar: 1.2rem;
        --font-size-time: 2.6rem;
        --spacing-sub: 25px;
    }
    
    .main-content {
        gap: 55px;
        padding: 45px 30px;
    }
    
    .date-time {
        letter-spacing: 8px;
    }
    
    .date-weekday {
        padding: 9px 18px;
    }
    
    .time-format-toggle {
        top: 12px;
        right: 12px;
        padding: 10px 14px;
        font-size: 1rem;
    }
    
    .time-format-toggle svg {
        width: 18px;
        height: 18px;
    }
}

@media (max-width: 480px) {
    :root {
        --font-size-year: 3.8rem;
        --font-size-month-day: 3rem;
        --font-size-separator: 1.9rem;
        --font-size-weekday: 1.2rem;
        --font-size-lunar: 1.1rem;
        --font-size-time: 2.2rem;
        --spacing-main: 12px;
        --spacing-sub: 22px;
    }
    
    .main-content {
        gap: 50px;
        padding: 40px 25px;
    }
    
    .date-time {
        letter-spacing: 7px;
        text-shadow:
            0 0 18px rgba(99, 102, 241, 0.8),
            0 0 35px var(--glow-primary),
            0 0 50px var(--glow-accent);
    }
    
    .date-weekday {
        padding: 8px 18px;
    }
    
    .date-lunar {
        margin-top: 14px;
    }
    
    .time-format-toggle {
        top: 10px;
        right: 10px;
        padding: 9px 14px;
        font-size: 0.95rem;
        gap: 7px;
    }
    
    .time-format-toggle svg {
        width: 17px;
        height: 17px;
    }
}

@media (max-width: 360px) {
    :root {
        --font-size-year: 3.2rem;
        --font-size-month-day: 2.5rem;
        --font-size-separator: 1.6rem;
        --font-size-weekday: 1.1rem;
        --font-size-lunar: 1rem;
        --font-size-time: 1.8rem;
    }
    
    .main-content {
        gap: 45px;
        padding: 35px 22px;
    }
    
    .container {
        padding: 18px;
    }
    
    .date-weekday {
        padding: 7px 16px;
    }
    
    .date-time {
        letter-spacing: 6px;
    }
    
    .time-format-toggle {
        top: 8px;
        right: 8px;
        padding: 8px 12px;
        font-size: 0.9rem;
        gap: 6px;
    }
    
    .time-format-toggle svg {
        width: 15px;
        height: 15px;
    }
}

@media (max-height: 500px) {
    .main-content {
        gap: 20px;
        padding: 20px;
    }
    
    .date-main {
        margin-bottom: 8px;
    }
    
    .date-sub {
        margin-bottom: 10px;
    }
    
    .date-time {
        margin-top: 4px;
    }
}

@media (orientation: landscape) and (max-height: 400px) {
    :root {
        --font-size-year: 2rem;
        --font-size-month-day: 1.5rem;
        --font-size-separator: 1.3rem;
        --font-size-time: 1.1rem;
    }
    
    .main-content {
        gap: 15px;
        padding: 15px;
    }
}

@media (prefers-reduced-motion: reduce) {
    .particle {
        animation: none;
        opacity: 0.3;
    }
    
    .bg-image {
        transition: none;
    }
    
    @keyframes fadeInDown {
        from { opacity: 0; }
        to { opacity: 1; }
    }
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg-dark: #0f172a;
        --color-text-primary: #f8fafc;
    }
}