/* ===== RESET & BASE ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Roboto, system-ui, -apple-system, sans-serif;
    background: #f0f4f8;
    color: #1a202c;
    line-height: 1.6;
    padding: 16px;
    min-height: 100vh;
}

.app-wrapper {
    max-width: 1200px;
    margin: 0 auto;
}

/* ===== HEADER ===== */
.header {
    background: linear-gradient(145deg, #0b2b4a, #1a4f7a);
    color: white;
    padding: 32px 24px 28px;
    border-radius: 24px;
    margin-bottom: 32px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(26, 79, 122, 0.25);
}

.header h1 {
    font-size: 2.2rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    margin-bottom: 6px;
}

.header .subhead {
    font-size: 1.05rem;
    opacity: 0.9;
    font-weight: 300;
    max-width: 640px;
    margin: 0 auto;
}

/* ===== NAVIGASI ===== */
.nav-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
    margin-bottom: 32px;
}

.nav-tabs button {
    padding: 10px 28px;
    border: none;
    border-radius: 60px;
    font-size: 1rem;
    font-weight: 600;
    background: #e9edf2;
    color: #2d3748;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.02);
    letter-spacing: 0.3px;
}

.nav-tabs button:hover {
    background: #d5dde6;
    transform: translateY(-2px);
    box-shadow: 0 6px 14px rgba(0, 0, 0, 0.06);
}

.nav-tabs button.active {
    background: #1a4f7a;
    color: #fff;
    box-shadow: 0 6px 16px rgba(26, 79, 122, 0.30);
}

/* ===== CARD ===== */
.card {
    background: #ffffff;
    border-radius: 20px;
    padding: 28px 32px;
    margin-bottom: 28px;
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.04);
    border: 1px solid #eef2f6;
    transition: box-shadow 0.2s;
}

.card h2 {
    font-size: 1.8rem;
    font-weight: 700;
    color: #0b2b4a;
    margin-bottom: 2px;
}

.card .card-sub {
    color: #4a5568;
    font-size: 0.95rem;
    border-bottom: 2px solid #edf2f7;
    padding-bottom: 14px;
    margin-bottom: 22px;
}

/* ===== FORM ===== */
.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 5px;
    color: #2d3748;
    font-size: 0.95rem;
}

.form-group .hint {
    font-weight: 400;
    font-size: 0.82rem;
    color: #718096;
    margin-left: 6px;
}

.form-row {
    display: flex;
    flex-wrap: wrap;
    gap: 18px;
    align-items: flex-end;
}

.form-row .form-group {
    flex: 1 1 180px;
    margin-bottom: 0;
}

input[type="text"],
select {
    width: 100%;
    padding: 10px 14px;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    font-size: 1rem;
    font-family: 'Courier New', monospace;
    background: #fafcfe;
    transition: border 0.2s, box-shadow 0.2s;
}

input[type="text"]:focus,
select:focus {
    outline: none;
    border-color: #2b6cb0;
    box-shadow: 0 0 0 4px rgba(43, 108, 176, 0.10);
    background: #ffffff;
}

input[type="text"].error {
    border-color: #e53e3e;
    background: #fff5f5;
}

/* ===== BUTTONS ===== */
.btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 6px;
}

.btn {
    padding: 10px 30px;
    border: none;
    border-radius: 60px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.btn-primary {
    background: #1a4f7a;
    color: white;
}
.btn-primary:hover {
    background: #0e3b5e;
    transform: translateY(-2px);
    box-shadow: 0 8px 18px rgba(26, 79, 122, 0.25);
}

.btn-secondary {
    background: #e9edf2;
    color: #2d3748;
}
.btn-secondary:hover {
    background: #d5dde6;
}

/* ===== HASIL ===== */
.result-box {
    background: #f7fafc;
    border-radius: 14px;
    padding: 16px 20px;
    border: 2px solid #e2e8f0;
    word-break: break-all;
    margin-top: 4px;
}

.result-box .label {
    font-weight: 600;
    color: #4a5568;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.result-box .value {
    font-family: 'Courier New', monospace;
    font-size: 1.3rem;
    letter-spacing: 1px;
    color: #1a202c;
    margin-top: 2px;
}

.result-box .value.highlight {
    color: #1a4f7a;
    font-weight: 700;
}

/* ===== SOLUSI STEP ===== */
.solution-toggle {
    margin-top: 24px;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    color: #1a4f7a;
    font-weight: 600;
    user-select: none;
    padding: 6px 12px 6px 6px;
    border-radius: 40px;
    background: #eef4fa;
    transition: background 0.15s;
}

.solution-toggle:hover {
    background: #dce6f2;
}

.solution-toggle .icon {
    font-size: 1.2rem;
    transition: transform 0.2s;
}

.solution-content {
    margin-top: 18px;
    padding: 18px 22px;
    background: #f0f5fa;
    border-radius: 14px;
    border-left: 5px solid #1a4f7a;
    max-height: 580px;
    overflow-y: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.88rem;
    white-space: pre-wrap;
    word-break: break-word;
    display: none;
    box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.02);
}

.solution-content.show {
    display: block;
}

.solution-content .step {
    margin-bottom: 14px;
    padding-bottom: 14px;
    border-bottom: 1px dashed #cbd5e0;
}

.solution-content .step:last-child {
    border-bottom: 0;
    margin-bottom: 0;
    padding-bottom: 0;
}

.solution-content .step-title {
    font-weight: 700;
    color: #0b2b4a;
    font-family: 'Segoe UI', sans-serif;
    font-size: 0.9rem;
}

.solution-content .step-data {
    color: #1e293b;
    padding-left: 8px;
    margin-top: 2px;
    font-size: 0.85rem;
}

/* ===== RESPONSIF ===== */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    .header {
        padding: 24px 16px 20px;
    }

    .header h1 {
        font-size: 1.6rem;
    }

    .card {
        padding: 20px 16px;
    }

    .card h2 {
        font-size: 1.4rem;
    }

    .nav-tabs button {
        padding: 8px 18px;
        font-size: 0.85rem;
    }

    .form-row {
        flex-direction: column;
        gap: 12px;
    }

    .form-row .form-group {
        flex: 1 1 auto;
        width: 100%;
    }

    .btn-group {
        flex-direction: column;
        width: 100%;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .result-box .value {
        font-size: 1rem;
    }

    .solution-content {
        font-size: 0.78rem;
        padding: 14px 16px;
        max-height: 400px;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.2rem;
    }

    .header .subhead {
        font-size: 0.9rem;
    }

    .card {
        padding: 14px 10px;
        border-radius: 16px;
    }

    .nav-tabs {
        gap: 6px;
    }

    .nav-tabs button {
        font-size: 0.75rem;
        padding: 6px 14px;
    }

    input[type="text"],
    select {
        font-size: 0.9rem;
        padding: 8px 10px;
    }

    .result-box .value {
        font-size: 0.9rem;
    }
}

/* ===== UTILITY ===== */
.hidden {
    display: none !important;
}
.text-muted {
    color: #718096;
}

/* scrollbar untuk solution */
.solution-content::-webkit-scrollbar {
    width: 6px;
}
.solution-content::-webkit-scrollbar-track {
    background: #e2e8f0;
    border-radius: 8px;
}
.solution-content::-webkit-scrollbar-thumb {
    background: #a0b8cc;
    border-radius: 8px;
}