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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: #667eea;
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
}

.header {
    background: white;
    padding: 40px 30px;
    border-radius: 12px;
    margin-bottom: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.header h1 {
    color: #667eea;
    font-size: 32px;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 15px;
    justify-content: center;
}

.header p {
    color: #666;
    font-size: 16px;
    display: flex;
    justify-content: center;
}

.form-card {
    background: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    margin-bottom: 20px;
}

.form-group {
    margin-bottom: 25px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    font-size: 16px;
    color: #333;
}

select,
input[type="number"] {
    width: 100%;
    padding: 12px;
    font-size: 15px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    background-color: white;
    cursor: pointer;
    transition: border-color 0.2s;
}

select:focus,
input[type="number"]:focus {
    outline: none;
    border-color: #667eea;
}

.drone-specs {
    margin-top: 10px;
    padding: 12px;
    background: #f5f5f5;
    border-radius: 6px;
    font-size: 14px;
    color: #666;
}

.checkbox-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.checkbox-item {
    display: flex;
    align-items: center;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    background: white;
}

.checkbox-item:hover {
    background: #f9fafb;
}

.checkbox-item.selected {
    background: #f0f4ff;
    border-color: #667eea;
}

.checkbox-item input {
    margin-right: 10px;
    width: 18px;
    height: 18px;
    cursor: pointer;
}

.submit-btn {
    width: 100%;
    padding: 16px;
    font-size: 18px;
    font-weight: 600;
    color: white;
    background: #667eea;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: transform 0.2s;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.submit-btn:hover {
    background: #9ca3af;
    /* transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(0,0,0,0.15); */
}

.submit-btn:active {
    transform: translateY(0);
}

.submit-btn:disabled {
    background: #9ca3af;
    cursor: not-allowed;
    transform: none;
}

.loading {
    text-align: center;
    padding: 40px;
    color: #667eea;
    font-size: 18px;
}

.spinner {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #667eea;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 20px auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.results {
    background: white;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    margin-top: 20px;
}

.results h2 {
    color: #333;
    font-size: 24px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.results-content {
    line-height: 1;
    color: #444;
    white-space: pre-wrap;
    padding-bottom: 20px;
}

.results-content ul {
    margin: 5px 0;
    padding-left: 0;
    list-style: none;
    line-height: 0.6;
}

.results-content li {
    margin: 0;
    padding-left: 30px;
    position: relative;
    line-height: 1.0;
}

.results-content li:before {
    content: "•";
    color: #667eea;
    font-weight: bold;
    font-size: 20px;
    position: absolute;
    left: 10px;
    line-height: 0.6;
}

.results-content h3 {
    color: #333;
    font-size: 20px;
    margin: 20px 0 10px 0;
    font-weight: 600;
}

.results-content h2 {
    color: #333;
    font-size: 24px;
    margin: 25px 0 15px 0;
    font-weight: 700;
}

.results-content strong {
    color: #222;
    font-weight: 600;
}

.warning {
    margin-bottom: 10px;
    padding: 10px;
    background: #fffbeb;
    border: 4px solid #f59e0b;
    border-radius: 12px;
}

.warning strong {
    color: #92400e;
    display: flex;
    align-items: center;
    justify-content: center;
}

.warning p {
    margin: 8px 0 0 0;
    color: #92400e;
    font-size: 14px;
}

.error {
    background: #fee;
    border: 2px solid #fcc;
    padding: 16px;
    border-radius: 8px;
    color: #c33;
    margin-top: 20px;
}

.icon {
    width: 24px;
    height: 24px;
}

.footer {
    background: white;
    padding: 20px;
    border-radius: 12px;
    margin-top: 20px;
    font-size: 14px;
    color: #666;
}

.footer h3 {
    color: #333;
    margin-bottom: 10px;
}

.footer a {
    color: #667eea;
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

/* ========================================
   MOBILE RESPONSIVE STYLES
   ======================================== */

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

    .container {
        max-width: 100%;
    }

    .header {
        padding: 25px 20px;
    }

    .header h1 {
        font-size: 24px;
        gap: 10px;
    }

    .header p {
        font-size: 14px;
        text-align: center;
    }

    .form-card {
        padding: 20px;
    }

    .form-group {
        margin-bottom: 20px;
    }

    label {
        font-size: 15px;
    }

    select,
    input[type="number"] {
        padding: 10px;
        font-size: 16px; /* Prevents zoom on iOS */
    }

    .checkbox-item {
        padding: 10px;
    }

    .checkbox-item input {
        width: 16px;
        height: 16px;
    }

    .submit-btn {
        padding: 14px;
        font-size: 16px;
    }

    .results {
        padding: 15px;
    }

    .results h2 {
        font-size: 20px;
        margin-bottom: 10px;
    }

    .results-content {
        font-size: 15px;
        padding-bottom: 20px;
    }

    .results-content h2 {
        font-size: 18px;
        margin: 15px 0 10px 0;
    }

    .results-content h3 {
        font-size: 16px;
        margin: 12px 0 8px 0;
    }

    .results-content li {
        padding-left: 20px;
        font-size: 14px;
        margin: 0;
        line-height: 1.0;
    }

    .results-content ul {
        margin: 3px 0;
    }

    .results-content li:before {
        font-size: 18px;
        left: 5px;
    }

    .warning {
        padding: 10px;
        font-size: 12px;
        margin-top: 15px;
    }

    .warning p {
        margin: 5px 0 0 0;
    }

    .footer {
        padding: 15px;
        font-size: 13px;
    }

    .icon {
        width: 20px;
        height: 20px;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 20px;
    }

    .header p {
        font-size: 13px;
        text-align: center;
    }

    .form-card {
        padding: 15px;
    }

    .results-content li {
        font-size: 13px;
        line-height: 1.0;
        margin: 0;
    }
}