/* ===================================
   SIMPLIFIED LANDING PAGE
   =================================== */

.landing-page {
    overflow: hidden;
    background-color: var(--color-bg);
}

.landing-container {
    position: relative;
    width: 100vw;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-bg);
    transition: background-color var(--transition-medium);
}

/* ===================================
   GRID OVERLAY
   =================================== */
.grid-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    grid-template-rows: repeat(8, 1fr);
    gap: 0;
}

/* ===================================
   GRID CELLS
   =================================== */
.grid-cell {
    position: relative;
    border: 1px solid var(--color-border);
    transition: border-color var(--transition-fast);
    perspective: 1000px;
}

.grid-cell.interactive {
    cursor: pointer;
}

.grid-cell.interactive:hover {
    border-color: var(--color-primary);
}

/* Flip Card Container */
.flip-card {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    transform-style: preserve-3d;
}

/* Group flip - when hovering any letter in a word, flip all letters in that word */
.grid-cell.interactive:hover .flip-card,
.grid-cell.word-hover .flip-card {
    transform: rotateY(180deg);
}

/* Card Faces */
.flip-card-front,
.flip-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.flip-card-front {
    background-color: transparent;
}

.flip-card-back {
    background-color: transparent;
    color: var(--color-primary);
    transform: rotateY(180deg);
    text-decoration: none;
    font-family: var(--font-heading);
    font-size: clamp(1.5rem, 3vw, 2.5rem);
    font-weight: 400; /* Regular weight for navigation */
    letter-spacing: -0.01em;
}

/* ESA Letters - Bold and 2x size */
.letter-esa {
    font-family: var(--font-heading);
    font-size: clamp(3rem, 6vw, 5rem); /* 2x the size */
    font-weight: 700; /* Bold */
    color: var(--color-primary);
    letter-spacing: -0.03em;
}

/* Navigation Letters - Regular weight, initially hidden */
.letter-nav {
    font-family: var(--font-heading);
    font-size: clamp(1.5rem, 3vw, 2.5rem);
    font-weight: 400; /* Regular weight */
    color: var(--color-primary);
    letter-spacing: -0.01em;
    opacity: 0; /* Hidden initially */
}

/* Show navigation letters on flip */
.flip-card-back .letter-nav {
    opacity: 1;
}

/* ===================================
   THEME TOGGLE CELL
   =================================== */
.theme-cell {
    cursor: pointer;
}

.theme-cell:hover {
    border-color: var(--color-primary);
}

.theme-icon {
    width: 60%;
    height: 60%;
    object-fit: contain;
    filter: brightness(0); /* Make black in light mode */
    transition: filter var(--transition-medium);
}

[data-theme="dark"] .theme-icon {
    filter: brightness(0) invert(1); /* Make white in dark mode */
}

/* ===================================
   RESPONSIVE DESIGN
   =================================== */
@media (max-width: 1024px) {
    .grid-overlay {
        grid-template-columns: repeat(10, 1fr);
        grid-template-rows: repeat(8, 1fr);
    }

    .letter-esa {
        font-size: clamp(2.5rem, 8vw, 4rem);
    }

    .letter-nav,
    .flip-card-back {
        font-size: clamp(1.25rem, 4vw, 2rem);
    }
}

@media (max-width: 768px) {
    .grid-overlay {
        grid-template-columns: repeat(6, 1fr);
        grid-template-rows: repeat(8, 1fr);
    }

    .letter-esa {
        font-size: clamp(2rem, 10vw, 3.5rem);
    }

    .letter-nav,
    .flip-card-back {
        font-size: clamp(1rem, 5vw, 1.75rem);
    }
}

@media (max-width: 480px) {
    .grid-overlay {
        grid-template-columns: repeat(6, 1fr);
        grid-template-rows: repeat(8, 1fr);
    }

    .letter-esa {
        font-size: clamp(1.5rem, 12vw, 2.5rem);
    }

    .letter-nav,
    .flip-card-back {
        font-size: clamp(0.875rem, 6vw, 1.5rem);
    }
}

/* ===================================
   EASTER EGG CELL
   =================================== */
.easter-egg-cell {
    cursor: pointer;
}

.easter-egg-cell:hover {
    border-color: var(--color-primary);
}

.easter-egg-key {
    width: 50%;
    height: 50%;
    object-fit: contain;
    animation: bounce 1s ease-in-out infinite;
}

/* Bouncing animation */
@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

/* ===================================
   ACCESSIBILITY
   =================================== */
@media (prefers-reduced-motion: reduce) {
    .flip-card {
        transition: none;
    }

    .easter-egg-key {
        animation: none;
    }
}