/* ================================================
   Premium Door Opening Intro Effect 🚪❄️
   Elegant Gate Animation
   ================================================ */

/* Full Screen Overlay - Winter Mountain Theme */
.door-intro {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: 999999;
    overflow: hidden;
    perspective: 2000px;
    background: transparent;
    pointer-events: all;
    opacity: 1;
    transition: opacity 0.8s ease;
}

.door-intro.fading {
    opacity: 0;
    pointer-events: none;
}

.door-intro.hidden {
    display: none;
}

/* Mountain Silhouettes - Removed for transparent background */
.door-intro::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 40%;
    background: transparent;
    pointer-events: none;
    z-index: 2;
    will-change: opacity;
}

/* Door Container */
.door-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    z-index: 3;
    contain: layout style;
}

/* Individual Door Panel - Optimized Ice Theme */
.door-panel {
    position: absolute;
    top: 0;
    width: 50%;
    height: 100%;
    background: linear-gradient(180deg,
        rgba(230, 245, 255, 0.95) 0%,
        rgba(200, 230, 250, 0.98) 20%,
        rgba(220, 240, 255, 0.96) 50%,
        rgba(200, 230, 250, 0.98) 80%,
        rgba(230, 245, 255, 0.95) 100%
    );
    box-shadow: 0 10px 40px rgba(100, 150, 180, 0.3);
    transition: transform 2s cubic-bezier(0.77, 0, 0.175, 1);
    transform-style: preserve-3d;
    will-change: transform;
    contain: layout style paint;
}

/* Left Door */
.door-left {
    left: 0;
    transform-origin: left center;
    border-right: 3px solid rgba(192, 192, 192, 0.6);
    box-shadow: inset -3px 0 10px rgba(255, 255, 255, 0.5);
}

/* Right Door */
.door-right {
    right: 0;
    transform-origin: right center;
    border-left: 3px solid rgba(192, 192, 192, 0.6);
    box-shadow: inset 3px 0 10px rgba(255, 255, 255, 0.5);
}

/* Door Frame Decoration - Classic Molding */
.door-panel::before {
    content: '';
    position: absolute;
    top: 5%;
    left: 10%;
    right: 10%;
    bottom: 5%;
    border: 5px solid rgba(192, 192, 192, 0.7);
    border-radius: 4px;
    background: linear-gradient(135deg,
        rgba(255, 255, 255, 0.3) 0%,
        transparent 50%,
        rgba(174, 214, 241, 0.2) 100%
    );
    box-shadow: inset 0 0 30px rgba(255, 255, 255, 0.4);
}

/* Door Pattern - Simplified Frost */
.door-panel::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image:
        /* Simple diagonal pattern */
        repeating-linear-gradient(
            45deg,
            transparent 0px,
            rgba(255, 255, 255, 0.05) 1px,
            transparent 2px,
            transparent 40px
        ),
        repeating-linear-gradient(
            -45deg,
            transparent 0px,
            rgba(255, 255, 255, 0.05) 1px,
            transparent 2px,
            transparent 40px
        );
    opacity: 0.5;
}

/* Door Opening Animation */
.door-intro.opening .door-left {
    transform: rotateY(-120deg);
}

.door-intro.opening .door-right {
    transform: rotateY(120deg);
}

/* Door Handle - Classic Crystal */
.door-handle {
    position: absolute;
    top: 50%;
    width: 100px;
    height: 100px;
    margin-top: -50px;
    background: radial-gradient(circle,
        rgba(255, 255, 255, 0.8) 0%,
        rgba(200, 230, 250, 0.6) 30%,
        rgba(174, 214, 241, 0.4) 60%,
        transparent 100%);
    border: 4px solid rgba(192, 192, 192, 0.8);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.4s ease;
    z-index: 10;
    cursor: pointer;
    box-shadow: 0 0 30px rgba(255, 255, 255, 0.5);
}

.door-left .door-handle {
    right: -50px;
}

.door-right .door-handle {
    left: -50px;
}

.door-handle::before {
    content: '';
    width: 60px;
    height: 60px;
    border: 3px solid rgba(192, 192, 192, 0.9);
    border-radius: 50%;
    background: radial-gradient(circle,
        rgba(255, 255, 255, 0.9) 0%,
        rgba(220, 240, 255, 0.7) 50%,
        rgba(174, 214, 241, 0.5) 100%
    );
    box-shadow: 0 0 20px rgba(255, 255, 255, 0.6);
    animation: crystalPulse 2s ease-in-out infinite;
}

@keyframes crystalPulse {
    0%, 100% {
        transform: scale(1);
        opacity: 1;
        box-shadow: 0 0 20px rgba(255, 255, 255, 0.6);
    }
    50% {
        transform: scale(1.05);
        opacity: 0.9;
        box-shadow: 0 0 30px rgba(255, 255, 255, 0.8);
    }
}

/* Center Content */
.door-content {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 5;
    text-align: center;
    pointer-events: none;
    opacity: 1;
    transition: all 0.8s cubic-bezier(0.77, 0, 0.175, 1);
}

.door-intro.opening .door-content {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.8);
}

/* Snowflake Icon - Winter Theme */
.door-icon {
    font-size: 6rem;
    margin-bottom: 2rem;
    display: block;
    animation: floatIcon 4s ease-in-out infinite;
    filter: drop-shadow(0 15px 40px rgba(255, 255, 255, 0.6));
    text-shadow:
        0 0 40px rgba(255, 255, 255, 0.8),
        0 0 20px rgba(174, 214, 241, 0.6);
}

@keyframes floatIcon {
    0%, 100% {
        transform: translateY(0) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(10deg);
    }
}

/* Title - Winter Theme */
.door-title {
    font-size: 4.5rem;
    font-weight: 200;
    color: #ffffff;
    margin-bottom: 1.5rem;
    letter-spacing: 1.5rem;
    text-transform: uppercase;
    line-height: 1;
    text-shadow:
        0 0 40px rgba(255, 255, 255, 0.8),
        0 5px 20px rgba(174, 214, 241, 0.6),
        2px 2px 4px rgba(100, 150, 180, 0.5);
}

/* Subtitle - Winter Theme */
.door-subtitle {
    font-size: 1.25rem;
    color: rgba(255, 255, 255, 0.95);
    margin-bottom: 3rem;
    font-weight: 300;
    letter-spacing: 0.5em;
    text-transform: uppercase;
    opacity: 0.9;
    text-shadow:
        0 2px 10px rgba(174, 214, 241, 0.6),
        0 0 20px rgba(255, 255, 255, 0.4);
}

/* Enter Button - Optimized */
.door-enter {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 20px 60px;
    background: rgba(255, 255, 255, 0.2);
    color: #ffffff;
    border: 3px solid rgba(255, 255, 255, 0.8);
    border-radius: 100px;
    font-weight: 500;
    font-size: 0.95rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    cursor: pointer;
    transition: all 0.5s cubic-bezier(0.77, 0, 0.175, 1);
    position: relative;
    overflow: hidden;
    pointer-events: all;
    box-shadow: 0 0 30px rgba(255, 255, 255, 0.4);
}

.door-enter::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.4);
    transform: translate(-50%, -50%);
    transition: width 0.6s ease, height 0.6s ease;
    z-index: -1;
}

.door-enter:hover::before {
    width: 400px;
    height: 400px;
}

.door-enter:hover {
    color: #ffffff;
    background: rgba(255, 255, 255, 0.3);
    border-color: rgba(255, 255, 255, 1);
    transform: translateY(-4px);
    box-shadow: 0 10px 40px rgba(255, 255, 255, 0.5);
}

.door-enter span {
    position: relative;
    z-index: 1;
}

/* Snowflakes Decoration - Optimized */
.door-snowflakes {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
    overflow: hidden;
    opacity: 0.5;
    z-index: 1;
    will-change: opacity;
}

.door-snowflake {
    position: absolute;
    color: rgba(255, 255, 255, 0.8);
    font-size: 1.5rem;
    animation: snowDrift linear infinite;
    filter: drop-shadow(0 0 8px rgba(174, 214, 241, 0.6));
    text-shadow: 0 0 10px rgba(255, 255, 255, 0.8);
}

.door-snowflake:nth-child(1) { left: 10%; animation-duration: 18s; animation-delay: 0s; }
.door-snowflake:nth-child(2) { left: 25%; animation-duration: 22s; animation-delay: 4s; font-size: 1.2rem; }
.door-snowflake:nth-child(3) { left: 40%; animation-duration: 20s; animation-delay: 8s; font-size: 1.8rem; }
.door-snowflake:nth-child(4) { left: 55%; animation-duration: 24s; animation-delay: 3s; }
.door-snowflake:nth-child(5) { left: 70%; animation-duration: 19s; animation-delay: 7s; font-size: 1.4rem; }
.door-snowflake:nth-child(6) { left: 85%; animation-duration: 21s; animation-delay: 10s; }

@keyframes snowDrift {
    0% {
        transform: translateY(-10vh) translateX(0) rotate(0deg);
        opacity: 0;
    }
    10% {
        opacity: 1;
    }
    90% {
        opacity: 1;
    }
    100% {
        transform: translateY(110vh) translateX(30px) rotate(360deg);
        opacity: 0;
    }
}

/* Light Beam Effect - Winter Theme */
.door-intro::after {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    width: 0%;
    height: 100%;
    transform: translateX(-50%);
    background: radial-gradient(
        ellipse,
        rgba(255, 255, 255, 0.6) 0%,
        rgba(174, 214, 241, 0.4) 30%,
        rgba(200, 230, 250, 0.2) 50%,
        transparent 70%
    );
    opacity: 0;
    transition: all 2s cubic-bezier(0.77, 0, 0.175, 1);
    pointer-events: none;
}

.door-intro.opening::after {
    width: 120%;
    opacity: 1;
}

/* Prevent Background Scroll */
body:has(.door-intro:not(.hidden)) {
    overflow: hidden;
}

/* Responsive */
@media (max-width: 768px) {
    .door-intro {
        perspective: 1000px;
    }

    .door-icon {
        font-size: 3.5rem;
        margin-bottom: 1.5rem;
        animation: none;
    }

    .door-title {
        font-size: 2rem;
        letter-spacing: 0.5rem;
    }

    .door-subtitle {
        font-size: 0.85rem;
        letter-spacing: 0.2em;
        margin-bottom: 2rem;
    }

    .door-enter {
        padding: 14px 32px;
        font-size: 0.75rem;
        letter-spacing: 0.15em;
    }

    .door-panel::before {
        top: 8%;
        left: 12%;
        right: 12%;
        bottom: 8%;
        border: 3px solid rgba(192, 192, 192, 0.6);
    }

    /* 모바일에서는 3D 회전 각도를 줄여서 성능 향상 */
    .door-intro.opening .door-left {
        transform: rotateY(-90deg);
    }

    .door-intro.opening .door-right {
        transform: rotateY(90deg);
    }

    /* 모바일에서 눈송이 애니메이션 간소화 */
    .door-snowflake {
        font-size: 1.2rem;
        animation: snowDriftMobile linear infinite;
    }

    @keyframes snowDriftMobile {
        0% {
            transform: translateY(-10vh) rotate(0deg);
            opacity: 0;
        }
        10% {
            opacity: 1;
        }
        90% {
            opacity: 1;
        }
        100% {
            transform: translateY(110vh) rotate(180deg);
            opacity: 0;
        }
    }

    /* 손잡이 크기 줄이기 */
    .door-handle {
        width: 80px;
        height: 80px;
        margin-top: -40px;
    }

    .door-left .door-handle {
        right: -40px;
    }

    .door-right .door-handle {
        left: -40px;
    }

    .door-handle::before {
        width: 50px;
        height: 50px;
        border: 2px solid rgba(192, 192, 192, 0.9);
        animation: none;
    }

    /* 모바일에서 패턴 단순화 */
    .door-panel::after {
        opacity: 0.3;
    }
}

/* Performance */
@media (prefers-reduced-motion: reduce) {
    .door-intro,
    .door-panel,
    .door-content,
    .door-icon,
    .door-enter {
        animation: none !important;
        transition-duration: 0.01s !important;
    }
}