styles.css

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&display=swap');

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

body {
    font-family: 'Inter', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container { width: 100%; max-width: 500px; }

.form-container {
    background: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

h1 { text-align: center; color: #374151; font-size: 28px; font-weight: 600; margin-bottom: 8px; }
.subtitle { text-align: center; color: #6b7280; margin-bottom: 32px; font-size: 16px; }

.validation-form { display: flex; flex-direction: column; gap: 20px; }
.input-group, .checkbox-group { display: flex; flex-direction: column; gap: 6px; }
.checkbox-group { flex-direction: row; align-items: flex-start; gap: 12px; }

label { font-weight: 500; color: #374151; font-size: 14px; }
.required { color: #dc2626; }

input[type="text"], input[type="email"], input[type="tel"], input[type="password"] {
    padding: 12px 16px;
    border: 2px solid #d1d5db;
    border-radius: 8px;
    font-size: 16px;
    transition: all 0.2s ease;
    outline: none;
}

input[type="checkbox"] { width: 18px; height: 18px; accent-color: #4f46e5; cursor: pointer; margin-top: 2px; }
.checkbox-group label { cursor: pointer; line-height: 1.5; }

/* Focus and Validation States */
input:focus { border-color: #4f46e5; box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1); }
input:valid:not(:placeholder-shown) { border-color: #059669; }
input:invalid:not(:focus):not(:placeholder-shown) { border-color: #dc2626; }

/* Error Messages - only show when field is invalid and touched */
.error-message {
    color: #dc2626;
    font-size: 14px;
    font-weight: 500;
    display: none;
    margin-top: 4px;
}

.input-group input:invalid:not(:focus):not(:placeholder-shown) + .error-message { display: block; }

/* Submit Button */
.submit-button {
    background: #4f46e5;
    color: white;
    border: none;
    padding: 14px 24px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-top: 12px;
}

.submit-button:hover { background: #3730a3; transform: translateY(-1px); }
.submit-button:active { transform: translateY(0); }

/* Disable submit when form invalid */
.validation-form:invalid .submit-button {
    background: #9ca3af;
    cursor: not-allowed;
    transform: none;
}

/* Success Popup */
.success-popup {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.success-popup:target { display: flex; }

.popup-content {
    background: white;
    padding: 40px;
    border-radius: 12px;
    text-align: center;
    max-width: 400px;
    margin: 20px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.popup-content h2 { color: #059669; margin-bottom: 16px; font-size: 24px; }
.popup-content p { color: #374151; line-height: 1.6; margin-bottom: 20px; }

.close-btn {
    display: inline-block;
    background: #4f46e5;
    color: white;
    padding: 10px 20px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s ease;
}

.close-btn:hover { background: #3730a3; transform: translateY(-1px); }

/* Links */
a { color: #4f46e5; text-decoration: none; }
a:hover { text-decoration: underline; }

/* Responsive */
@media (max-width: 640px) {
    .form-container { padding: 24px; margin: 10px; }
    h1 { font-size: 24px; }
    .subtitle { font-size: 14px; }
}