:root {
    --bg-color: #050505;
    --surface: #121212;
    --surface-active: #1a1a1a;
    --border-color: rgba(255, 255, 255, 0.1);
    --text-primary: #ffffff;
    --text-secondary: #a1a1a1;
    --text-dim: #717171;
    --accent-color: #ffffff;
    --accent-bg: #ffffff;
    --accent-text: #000000;
    
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    
    --border-radius: 14px;
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, system-ui, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.5;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
}

.app-container {
    max-width: 450px;
    margin: 0 auto;
    padding: 20px;
    padding-bottom: 100px;
}

/* Header */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 0 30px 0;
}

.brand h1 {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.user-balance {
    background: var(--surface);
    padding: 6px 14px;
    border-radius: 40px;
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
}

.user-balance span {
    font-weight: 600;
}

/* Section Transitions */
.section {
    display: none;
    opacity: 0;
}

.section.active {
    display: block;
    animation: fadeIn 0.4s ease forwards;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

/* Minimalist Cards */
.card {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 24px;
    margin-bottom: 16px;
}

.card h2 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 20px;
}

/* Form Elements */
.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    font-size: 12px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-weight: 500;
}

select, input {
    width: 100%;
    background: #000000;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-primary);
    padding: 14px 16px;
    font-size: 16px;
    outline: none;
    transition: var(--transition);
    appearance: none;
    -webkit-appearance: none;
}

select:focus, input:focus {
    border-color: #555;
    background: #080808;
}

/* Buttons */
.btn {
    width: 100%;
    padding: 14px;
    border: none;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: var(--transition);
}

.btn-primary {
    background: var(--accent-bg);
    color: var(--accent-text);
    border: 1px solid var(--accent-bg);
}

.btn-primary:active {
    background: #e0e0e0;
    transform: translateY(1px);
}

.btn-outline {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-outline:active {
    background: var(--surface-active);
    border-color: #444;
}

/* Bottom Nav */
nav.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.9);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    display: flex;
    justify-content: space-around;
    padding: 12px 0 28px 0;
    border-top: 1px solid var(--border-color);
    z-index: 100;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    color: var(--text-dim);
    font-size: 11px;
    font-weight: 600;
    gap: 6px;
    cursor: pointer;
    transition: var(--transition);
    opacity: 0.7;
}

.nav-item.active {
    color: var(--text-primary);
    opacity: 1;
}

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

/* Grid & History Items */
.grid-list {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.grid-item {
    border: 1px solid var(--border-color);
    padding: 16px;
    border-radius: 12px;
    text-align: center;
    font-size: 14px;
}

.history-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

.history-item:last-child {
    border-bottom: none;
}

.status-badge {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.2px;
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(4px);
    display: none;
    align-items: center;
    justify-content: center;
    padding: 20px;
    z-index: 1000;
}

.modal {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 30px;
    width: 100%;
    max-width: 400px;
}

#modal-number {
    font-size: 24px;
    font-weight: 700;
    margin: 20px 0;
}

/* Helpers */
.text-success { color: var(--success); }
.text-danger { color: var(--danger); }
.text-warning { color: var(--warning); }