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

body {
    background: #000000;
    background: #0a0a0a;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding: 2rem 1.5rem 6rem 1.5rem;
    font-family: 'Inter', sans-serif;
    position: relative;
}

/* site logo top left */
.site-logo {
    position: fixed;
    top: 20px;
    left: 28px;
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.logo-image {
    height: 60px;
    width: auto;
    display: block;
}

.content {
    width: 100%;
    max-width: 580px;
    margin-top: 100px;
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
}

/* clean black card */
.refill-card {
    background: #0f0f0f;
    border: 1px solid #2a2a2a;
    border-radius: 28px;
    padding: 42px 32px;
    width: 100%;
    box-shadow: 0 12px 24px -16px #000000;
}

h2 {
    font-size: 2rem;
    font-weight: 500;
    letter-spacing: 1px;
    margin-bottom: 28px;
    color: #ffffff;
    font-family: 'Outfit', sans-serif;
    border-bottom: 1px solid #2a2a2a;
    padding-bottom: 14px;
}

.input-container {
    position: relative;
    margin-bottom: 28px;
}

input {
    width: 100%;
    padding: 18px 20px;
    border-radius: 20px;
    border: 1px solid #333333;
    background: #111111;
    color: white;
    font-size: 1rem;
    transition: all 0.2s ease;
}

input:focus {
    outline: none;
    border-color: #555555;
    background: #1a1a1a;
}

input::placeholder {
    color: #666666;
}

button {
    width: 100%;
    padding: 18px 20px;
    border: none;
    border-radius: 20px;
    background: #1e2a2a;
    border: 1px solid #3d5a5a;
    color: #ccf0f0;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s ease;
}

button:hover:not(:disabled) {
    background: #254040;
    border-color: #5a8080;
}

button:disabled {
    background: #2a2a2a;
    border-color: #444444;
    color: #888888;
    cursor: not-allowed;
    opacity: 0.7;
}

.message {
    margin-top: 24px;
    font-size: 0.95rem;
    min-height: 48px;
    padding: 12px 18px;
    border-radius: 16px;
    background: #111111;
    border: 1px solid #333333;
    color: #dddddd;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.success {
    background: #1a2a1a;
    border-color: #3d5a3d;
    color: #9ed9b5;
}

.error {
    background: #2a1a1a;
    border-color: #5a3d3d;
    color: #ffb9b9;
}

.loading {
    background: #1a1a2a;
    border-color: #3d3d5a;
    color: #b8d2ff;
    font-style: italic;
}

/* Bottom Navigation Bar */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: #111111;
    border-top: 1px solid #2a2a2a;
    display: flex;
    justify-content: center;
    padding: 10px 20px;
    z-index: 1000;
    backdrop-filter: blur(10px);
    box-shadow: 0 -5px 20px rgba(0, 0, 0, 0.5);
}

.nav-container {
    width: 100%;
    max-width: 500px;
    display: flex;
    justify-content: space-around;
    gap: 10px;
}

.nav-btn {
    flex: 1;
    background: #1a1a1a;
    border: 1px solid #3a3a3a;
    color: #f0f0f0;
    padding: 12px 16px;
    border-radius: 40px;
    font-size: 0.95rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    cursor: pointer;
    transition: 0.15s;
    text-decoration: none;
}

.nav-btn:hover {
    background: #252525;
    border-color: #555555;
    transform: translateY(-2px);
}

.nav-btn i {
    font-size: 1rem;
}

.nav-btn.active {
    background: #1e2a2a;
    border-color: #3d5a5a;
    color: #ccf0f0;
}

.nav-btn.active:hover {
    background: #254040;
}

/* tiny credit line */
.tiny-credit {
    margin-top: 16px;
    font-size: 0.7rem;
    color: #555555;
    text-align: center;
}