:root {
    --bg-dark: #0a0a0c;
    --card-bg: rgba(25, 25, 30, 0.6);
    --primary: #D4AF37;
    /* Gold Elite */
    --accent: #00f3ff;
    /* Neon Cyber */
    --text: #ffffff;
    --text-muted: #888899;
    --shadow: 0 10px 40px rgba(0, 0, 0, 0.8);
    --border: 1px solid rgba(255, 255, 255, 0.05);
    --gold-glow: 0 0 15px rgba(212, 175, 55, 0.4);
    --font-main: 'Outfit', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    background: var(--bg-dark);
    color: var(--text);
    font-family: var(--font-main);
    overflow: hidden;
    height: 100vh;
    height: 100dvh;
    display: flex;
    justify-content: center;
}

.app-container {
    width: 100%;
    max-width: 480px;
    height: 100vh;
    height: 100dvh;
    display: flex;
    flex-direction: column;
    position: relative;
    background: radial-gradient(circle at top right, rgba(212, 175, 55, 0.05), transparent),
        radial-gradient(circle at bottom left, rgba(0, 243, 255, 0.05), transparent);
}

/* HEADER */
.main-header {
    padding: 25px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: var(--border);
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo-area i {
    font-size: 24px;
    color: var(--primary);
}

.logo-area h1 {
    font-size: 1.2rem;
    font-weight: 800;
    letter-spacing: 2px;
}

.logo-area h1 span {
    color: var(--primary);
    margin-left: 2px;
}

.header-actions button {
    background: rgba(255, 255, 255, 0.05);
    border: none;
    color: var(--text);
    width: 40px;
    height: 40px;
    border-radius: 12px;
    margin-left: 8px;
    cursor: pointer;
    transition: 0.3s;
}

/* VIEWS */
.view {
    display: none;
    flex: 1;
    overflow-y: auto;
    padding: 20px 20px 100px 20px;
    animation: fadeIn 0.4s ease-out;
}

.view.active {
    display: flex;
    flex-direction: column;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* DASHBOARD */
.hero-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-bottom: 30px;
}

.stat-card {
    background: var(--card-bg);
    border: var(--border);
    padding: 20px;
    border-radius: 20px;
    text-align: center;
    backdrop-filter: blur(10px);
}

.stat-val {
    display: block;
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 5px;
}

.stat-label {
    font-size: 0.6rem;
    color: var(--text-muted);
    letter-spacing: 1.5px;
}

.section-title {
    margin-bottom: 20px;
}

.section-title h2 {
    font-size: 0.8rem;
    font-weight: 800;
    color: var(--text-muted);
    letter-spacing: 2px;
}

.category-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.category-card {
    background: var(--card-bg);
    border: var(--border);
    padding: 20px;
    border-radius: 18px;
    cursor: pointer;
    transition: 0.3s;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.category-card:active {
    transform: scale(0.95);
    border-color: var(--primary);
}

.category-card i {
    font-size: 24px;
    color: var(--accent);
}

.category-card span {
    font-size: 0.85rem;
    font-weight: 600;
}

/* STUDY AREA */
.study-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
}

.btn-back {
    background: none;
    border: none;
    color: var(--text);
    font-size: 1.2rem;
    cursor: pointer;
}

.study-header h2 {
    font-size: 1rem;
    font-weight: 800;
    letter-spacing: 2px;
    color: var(--primary);
}

#study-progress {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.flashcard-container {
    perspective: 1000px;
    width: 100%;
    max-width: 360px;
    aspect-ratio: 1/1;
    /* Square for focus */
    margin: 0 auto 30px;
}

.flashcard {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}

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

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: var(--card-bg);
    border: 2px solid rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 20px;
    box-shadow: var(--shadow);
    backdrop-filter: blur(20px);
}

.card-back {
    transform: rotateY(180deg);
    border-color: var(--primary);
}

.lang-tag {
    position: absolute;
    top: 30px;
    left: 40px;
    font-size: 0.6rem;
    padding: 4px 12px;
    border-radius: 100px;
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-muted);
    font-weight: 800;
}

.word-display {
    font-size: 2.2rem;
    font-weight: 800;
    text-align: center;
}

.hint {
    position: absolute;
    bottom: 20px;
    color: var(--text-muted);
    font-size: 0.7rem;
    opacity: 0.5;
}

.btn-audio {
    margin-top: 15px;
    background: var(--primary);
    border: none;
    padding: 10px 20px;
    border-radius: 100px;
    color: #000;
    font-weight: 800;
    font-size: 0.8rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: var(--gold-glow);
}

.phonetic-helper {
    margin-top: 15px;
    font-size: 0.85rem;
    color: var(--text-muted);
    letter-spacing: 1px;
    background: rgba(255, 255, 255, 0.03);
    padding: 8px 15px;
    border-radius: 12px;
    border: 1px dashed rgba(255, 255, 255, 0.1);
}

.phonetic-helper b {
    color: var(--accent);
    text-transform: lowercase;
    font-size: 1rem;
    margin-left: 4px;
    text-shadow: 0 0 10px rgba(0, 243, 255, 0.3);
}

/* CONTROLS */
.btn-control {
    width: 100%;
    background: linear-gradient(90deg, #111, #1a1a1e);
    border: 1px solid #333;
    padding: 20px;
    border-radius: 20px;
    color: var(--text);
    font-weight: 800;
    letter-spacing: 2px;
    cursor: pointer;
    transition: 0.3s;
}

.btn-control:active {
    transform: scale(0.98);
}

/* NAVIGATION */
.bottom-nav {
    padding: 15px 30px;
    display: flex;
    justify-content: space-around;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(20px);
    border-top: var(--border);
}

.nav-item {
    background: none;
    border: none;
    color: var(--text-muted);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    transition: 0.3s;
}

.nav-item i {
    font-size: 20px;
}

.nav-item span {
    font-size: 0.6rem;
    font-weight: 800;
    text-transform: uppercase;
}

.nav-item.active {
    color: var(--primary);
}

/* TOAST */
.toast {
    position: fixed;
    bottom: 100px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background: var(--primary);
    color: #000;
    padding: 12px 25px;
    border-radius: 100px;
    font-weight: 800;
    font-size: 0.8rem;
    opacity: 0;
    transition: 0.4s;
    pointer-events: none;
    z-index: 1000;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* INSTALL BANNER */
.install-banner {
    display: none;
    background: linear-gradient(135deg, var(--primary) 0%, #b8860b 100%);
    color: #000;
    padding: 15px 20px;
    border-radius: 20px;
    margin: 10px 20px 20px;
    align-items: center;
    justify-content: space-between;
    box-shadow: 0 10px 20px rgba(212, 175, 55, 0.2);
    animation: slideInUp 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    z-index: 100;
}

@keyframes slideInUp {
    from {
        transform: translateY(20px);
        opacity: 0;
    }

    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.install-banner span {
    font-size: 0.8rem;
    font-weight: 800;
    text-transform: uppercase;
}

.btn-install-now {
    background: #000;
    color: #fff;
    border: none;
    padding: 8px 16px;
    border-radius: 12px;
    font-weight: 800;
    font-size: 0.7rem;
    cursor: pointer;
    text-transform: uppercase;
}