:root {
    --bg-main: #0f0f1a;
    --bg-card: rgba(77, 77, 87, 0.3);
    --text-main: #e0e0ff;
    --accent-main: #00eaff;
    --accent-soft: rgba(0, 234, 255, 0.2);
    --radius-md: 1rem;
    --shadow-hover: 0 8px 32px rgba(0, 234, 255, 0.15);
    --transition: 0.35s ease;
}

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

body {
    background-image: url("../images/big-ben.jpg");
    background-size: cover;
    background-position: center;
    color: var(--text-main);
    font-family: 'Montserrat', sans-serif;
    min-height: 100vh;
    padding: 2rem 1rem;
}

h1 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: clamp(2rem, 5vw, 3.5rem);
    color: var(--accent-main);
}

/* Вкладки категорій */
.categories__tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    background-position: center;
    background-size: cover;
    justify-content: center;
    margin-bottom: 2rem;
}

.tab__btn {
    padding: 1.5rem 1.8rem;
    background: var(--bg-card);
    border: 2px solid var(--accent-soft);
    border-radius: var(--radius-md);
    color: var(--text-main);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    backdrop-filter: blur(10px);
}

.tab__btn.active,
.tab__btn:hover {
    background: var(--accent-main);
    color: #000;
    border-color: var(--accent-main);
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}


.cards__container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    max-width: 1800px;
    margin: 0 auto;
}

.card {
    position: relative;
    height: clamp(15rem, 10vh, 25rem);
    perspective: 1000px;
    cursor: pointer;
    transition: transform 0.3s ease;

}

.card__inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

.card.flipped .card__inner {
    transform: rotateY(180deg);
}

.card__front,
.card__back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-hover);
    background: var(--bg-card);
    backdrop-filter: blur(5px);
    border: 2px solid var(--accent-soft);
}

.card__front {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
}

.card__image {
    width: 80%;
    height: auto;
    max-height: 8rem;
    object-fit: contain;
    margin-bottom: 1rem;
}

.card__title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-main);
    text-align: center;
}

.card__back {
    transform: rotateY(180deg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    text-align: center;
}

.card__translation {
    font-size: 2.2rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.card__transcription {
    font-size: 1.3rem;
    color: var(--accent-main);
    margin-bottom: 1.5rem;
}

.sound__btn {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    font-size: clamp(1.2rem, 3vw, 1.5rem);
    cursor: pointer;
    transition: var(--transition);
}

.sound__btn:hover {
    transform: scale(1.15);
    box-shadow: 0 0 20px var(--accent-main);
}