body {
    margin: 0;
    background: #000;
    font-family: "Segoe UI", Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    color: #fff;
}

.container {
    width: 360px;
    background: #0f0f0f;
    padding: 40px;
    border-radius: 14px;
    box-shadow: 0 8px 30px rgba(0,0,0,0.5);
}

.tabs {
    display: flex;
    margin-bottom: 30px;
    position: relative;
}

.tab {
    flex: 1;
    text-align: center;
    padding: 12px 0;
    cursor: pointer;
    font-weight: 600;
    letter-spacing: 0.5px;
    color: #aaa;
    user-select: none;
    transition: 0.25s;
}

.tab:hover { color: #fff; }

input[type="radio"] { display: none; }

.underline {
    position: absolute;
    bottom: 0;
    height: 2px;
    width: 50%;
    background: #fff;
    transition: 0.3s ease;
}

#register:checked ~ .tabs .underline {
    transform: translateX(100%);
}

#login:checked ~ .tabs label[for="login"],
#register:checked ~ .tabs label[for="register"] {
    color: #fff;
}

form {
    display: none;
    flex-direction: column;
}

#login:checked ~ #loginForm { display: flex; }
#register:checked ~ #registerForm { display: flex; }

input {
    background: #000;
    border: 1px solid #333;
    padding: 13px;
    border-radius: 8px;
    color: #fff;
    margin-bottom: 18px;
    font-size: 15px;
    transition: border 0.22s ease;
    box-shadow: inset 0 0 0 rgba(255,255,255,0);
}

input:focus {
    border-color: #fff;
    outline: none;
    box-shadow: inset 0 0 8px rgba(255,255,255,0.08);
}

button {
    background: #fff;
    color: #000;
    border: none;
    padding: 13px;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    letter-spacing: 0.5px;
}

button:hover {
    background: #e5e5e5;
}

.back-home {
    margin-top: 28px;
    width: 100%;
    background: #1a1a1a;
    color: #fff;
    border: 1px solid #333;
    padding: 12px;
    border-radius: 8px;
    font-size: 14px;
    letter-spacing: 0.4px;
    cursor: pointer;
}

.back-home:hover {
    background: #2a2a2a;
}

#message {
    position: fixed;
    bottom: 25px;
    right: 25px;
    min-width: 260px;
    max-width: 320px;

    padding: 14px 18px;
    border-radius: 12px;

    font-size: 15px;
    font-weight: 500;
    color: #fff;

    backdrop-filter: blur(12px);
    background: rgba(20, 20, 20, 0.65);
    border: 1px solid rgba(255,255,255,0.12);

    box-shadow: 0 6px 25px rgba(0, 0, 0, 0.35);

    opacity: 0;
    transform: translateY(20px);
    pointer-events: none;

    transition:
        opacity 0.45s ease,
        transform 0.45s cubic-bezier(0.16, 1, 0.3, 1),
        background 0.3s ease,
        border 0.3s ease;

    z-index: 9999;
}

#message.show {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

#message.success {
    background: rgba(0, 200, 0, 0.18);
    border: 1px solid rgba(0, 200, 0, 0.4);
    color: #b6ffb6;
}

#message.error {
    background: rgba(255, 0, 0, 0.18);
    border: 1px solid rgba(255, 0, 0, 0.4);
    color: #ffb6b6;
}

#message.warning {
    background: rgba(255, 255, 0, 0.18);
    border: 1px solid rgba(255, 255, 0, 0.4);
    color: #fff7b6;
}