:root {
    --primary-orange: #FF6B00;
    --dark-orange: #E65A00;
    --light-orange: #FF8E33;
    --bg-gray: #F8F9FA;
    --text-dark: #2D3436;
    --white: #FFFFFF;
    --success: #27AE60;
    --error: #D63031;
}

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

body {
    background-color: var(--bg-gray);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: var(--text-dark);
}

.checkout-container {
    background: var(--white);
    width: 100%;
    max-width: 400px;
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    margin: 1rem;
}

.header {
    text-align: center;
    margin-bottom: 2rem;
}

.logo {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--primary-orange);
    letter-spacing: -1px;
}

.logo span {
    color: var(--text-dark);
}

.step-container {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

.step-container.active {
    display: block;
}

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

h2 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    text-align: center;
}

p.subtitle {
    font-size: 0.9rem;
    color: #636E72;
    text-align: center;
    margin-bottom: 1.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #636E72;
}

input {
    width: 100%;
    padding: 0.8rem 1rem;
    border: 2px solid #DFE6E9;
    border-radius: 12px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

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

.btn {
    width: 100%;
    padding: 1rem;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
}

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

.btn-primary:hover {
    background-color: var(--dark-orange);
}

.btn-primary:disabled {
    background-color: #FAB1A0;
    cursor: not-allowed;
}

.ussd-animation {
    text-align: center;
    padding: 1rem;
}

.phone-icon {
    font-size: 4rem;
    color: var(--primary-orange);
    margin-bottom: 1rem;
    animation: pulse 1.5s infinite;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

.alert {
    padding: 1rem;
    border-radius: 12px;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    display: none;
}

.alert-error {
    background-color: #FFEAA7;
    color: #D63031;
    border: 1px solid var(--error);
    display: block;
}

.loading-spinner {
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.fee-info {
    background-color: #F8F9FA;
    padding: 1rem;
    border-radius: 12px;
    margin-bottom: 1.5rem;
    border-left: 4px solid var(--primary-orange);
}

.fee-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
}

.fee-total {
    border-top: 1px solid #DFE6E9;
    padding-top: 0.5rem;
    font-weight: 800;
    font-size: 1.1rem;
}

.success-screen {
    text-align: center;
}

.success-icon {
    font-size: 5rem;
    color: var(--success);
    margin-bottom: 1.5rem;
}