/* =======================
    DARK MODE DESIGN
   ======================= */
   body {
    font-family: 'Poppins', sans-serif;
    background-color: #121212;
    color: #ffffff;
    text-align: center;
    margin: 0;
    padding: 0;
}

/* HEADER */
.main-header {
    background-color: #1e1e1e;
    padding: 20px;
    font-size: 1.5rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    box-shadow: 0px 4px 10px rgba(255, 255, 255, 0.1);
}

/* WELCOME SECTION */
main header h1 {
    color: #ffcc00;
    font-size: 2rem;
}

p {
    font-size: 1.1rem;
    line-height: 1.5;
}

/* NAVIGASI FITUR */
.nav-fitur {
    margin-top: 20px;
}

.nav-fitur button {
    background: #ffcc00;
    border: none;
    color: #121212;
    font-size: 1rem;
    font-weight: bold;
    padding: 12px 20px;
    margin: 5px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.nav-fitur button:hover {
    background: #ff9900;
}

/* NAVIGATION ACTIVE */
.nav-fitur-active {
    background: #ff6600 !important;
    color: white !important;
}

/* SECTION STYLE */
section {
    background: #1e1e1e;
    padding: 20px;
    margin: 20px auto;
    width: 80%;
    max-width: 500px;
    border-radius: 10px;
    box-shadow: 0px 4px 10px rgba(255, 255, 255, 0.1);
    display: none;
}

#persegi-section {
    display: block; /* Tampilkan default */
}

/* FORM INPUT */
form {
    display: flex;
    flex-direction: column;
    align-items: center;
}

label {
    font-size: 1rem;
    margin-bottom: 5px;
    font-weight: bold;
}

input {
    width: 80%;
    padding: 10px;
    margin-bottom: 10px;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    background: #333;
    color: white;
    outline: none;
}

input:focus {
    border: 2px solid #ffcc00;
}

/* BUTTON */
button {
    background: #ffcc00;
    border: none;
    color: #121212;
    font-size: 1rem;
    font-weight: bold;
    padding: 12px 20px;
    margin-top: 10px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
}

button:hover {
    background: #ff9900;
}

/* HASIL OUTPUT */
p#luas-hasil, 
p#keliling-hasil, 
p#luas-hasil-persegi-panjang {
    font-size: 1.3rem;
    font-weight: bold;
    color: #ffcc00;
    margin-top: 10px;
}

/* FOOTER */
footer {
    margin-top: 30px;
    padding: 10px;
    background: #1e1e1e;
    font-size: 0.9rem;
    color: #ffcc00;
}

/* RESPONSIVE */
@media (max-width: 600px) {
    section {
        width: 90%;
    }

    button {
        width: 90%;
    }

    input {
        width: 90%;
    }
}