:root {
    --bg-gradient: linear-gradient(135deg, #1a2a6c, #b21f1f, #fdbb2d);
    --card-bg: rgba(255, 255, 255, 0.1);
    --card-border: rgba(255, 255, 255, 0.2);
    --card-hover: rgba(255, 255, 255, 0.25);
    --text-color: #ffffff;
    --gold: #ffd700;
    --red: #ff4757;
    --green: #2ed573;
    --modal-bg: #ffffff;
    --modal-text: #2f3542;
}

body {
    font-family: 'Poppins', sans-serif;
    background: var(--bg-gradient);
    background-size: 400% 400%;
    animation: gradientBG 15s ease infinite;
    color: var(--text-color);
    margin: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    overflow-x: hidden;
}

@keyframes gradientBG {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.container {
    width: 90%;
    max-width: 1100px;
    padding: 40px 20px;
    text-align: center;
    position: relative;
    z-index: 10;
}

header h1 {
    font-family: 'Mountains of Christmas', cursive;
    font-size: 4rem;
    color: var(--gold);
    text-shadow: 0 4px 10px rgba(0,0,0,0.3);
    margin-bottom: 0.5rem;
    letter-spacing: 2px;
}

header p {
    font-size: 1.2rem;
    margin-bottom: 2.5rem;
    font-weight: 300;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

#reset-btn {
    background: rgba(255,255,255,0.1);
    border: 1px solid var(--text-color);
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    backdrop-filter: blur(5px);
    margin-bottom: 30px;
}

#reset-btn:hover {
    background: var(--text-color);
    color: #b21f1f;
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}

/* Calendar Grid */
.calendar-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 20px;
    perspective: 1000px;
}

/* Day Box (Door) */
.day-box {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--card-border);
    border-radius: 15px;
    height: 140px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    position: relative;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.37);
    overflow: hidden;
}

.day-box:not(.locked):hover {
    transform: translateY(-10px) scale(1.05);
    background: var(--card-hover);
    border-color: var(--gold);
    box-shadow: 0 15px 30px rgba(0,0,0,0.3);
}

.day-box::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    transform: rotate(45deg);
    pointer-events: none;
    transition: 0.5s;
    opacity: 0;
}

.day-box:hover::before {
    opacity: 1;
}

.day-number {
    font-family: 'Mountains of Christmas', cursive;
    font-size: 3.5rem;
    font-weight: bold;
    color: var(--text-color);
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
    z-index: 2;
    transition: transform 0.3s;
}

/* Locked State */
.day-box.locked {
    cursor: not-allowed;
    opacity: 0.7;
    background: rgba(0, 0, 0, 0.2);
    border-color: rgba(255, 255, 255, 0.1);
}

.day-box.locked:hover {
    transform: none;
}

.day-box.locked .day-number {
    color: rgba(255, 255, 255, 0.5);
}

.lock-icon {
    position: absolute;
    bottom: 10px;
    right: 10px;
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.5);
}

/* Shake Animation for Locked Items */
@keyframes shake {
    0% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    50% { transform: translateX(5px); }
    75% { transform: translateX(-5px); }
    100% { transform: translateX(0); }
}

.shake {
    animation: shake 0.4s ease-in-out;
}

/* Opened State */
.day-box.opened {
    background: rgba(46, 213, 115, 0.2); /* Green tint */
    border-color: var(--green);
}

.opened-indicator {
    font-size: 3rem;
    animation: bounceIn 0.6s cubic-bezier(0.215, 0.610, 0.355, 1.000);
}

@keyframes bounceIn {
    0% { opacity: 0; transform: scale(0.3); }
    50% { opacity: 1; transform: scale(1.05); }
    70% { transform: scale(0.9); }
    100% { transform: scale(1); }
}

/* Modal */
.hidden {
    display: none !important;
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(5px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal.show {
    opacity: 1;
}

.modal-content {
    background: var(--modal-bg);
    color: var(--modal-text);
    padding: 40px;
    border-radius: 20px;
    width: 90%;
    max-width: 500px;
    text-align: center;
    position: relative;
    box-shadow: 0 20px 50px rgba(0,0,0,0.3);
    transform: scale(0.8);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.modal.show .modal-content {
    transform: scale(1);
}

.close-btn {
    position: absolute;
    top: 15px;
    right: 20px;
    font-size: 2rem;
    cursor: pointer;
    color: #aaa;
    transition: color 0.2s;
}

.close-btn:hover {
    color: var(--red);
}

#modal-day {
    font-family: 'Mountains of Christmas', cursive;
    font-size: 2.5rem;
    color: var(--red);
    margin-top: 0;
}

#modal-image {
    font-size: 5rem;
    margin: 20px 0;
    filter: drop-shadow(0 5px 5px rgba(0,0,0,0.2));
}

#modal-message {
    font-size: 1.1rem;
    line-height: 1.6;
    color: #555;
}

/* Responsive */
@media (max-width: 600px) {
    header h1 { font-size: 2.5rem; }
    .calendar-grid { grid-template-columns: repeat(auto-fill, minmax(100px, 1fr)); }
    .day-box { height: 100px; }
    .day-number { font-size: 2.5rem; }
}