*, *::before, *::after { box-sizing: border-box; }

html { font-size: 62.5%; }

body {
    margin: 0;
    font-family: ProximaNova, Arial, sans-serif;
    font-size: 1.6rem;
    line-height: 1.5;
    color: #333;
    background: #f2f2f2;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

h1 {
    color: #000;
    font-size: 3rem;
    font-weight: 900;
    line-height: 1.33;
    text-transform: uppercase;
    margin: 0 0 20px;
}

@media (min-width: 576px) {
    h1 { font-size: 3.6rem; line-height: 1.2; }
}

@media (min-width: 992px) {
    h1 { font-size: 4rem; line-height: 1; }
}

p { margin: 0 0 20px; }

.introduction {
    font-size: 1.7rem;
    line-height: 1.5;
    margin-bottom: 30px;
}

/* ---------- Page Header / Footer ---------- */

.page-header {
    background: #262626;
    border-bottom: 3px solid #2785cb;
    padding: 18px 30px;
}

.page-header-inner,
.page-footer-inner {
    max-width: 1200px;
    margin: 0 auto;
}

.page-header-title {
    color: #fff;
    font-size: 2.2rem;
    font-weight: 400;
    line-height: 1.2;
    letter-spacing: .3px;
}

.page-footer {
    background: #333333;
    padding: 18px 20px;
    text-align: center;
    color: #cccccc;
    font-size: 1.2rem;
    margin-top: auto;
}

/* ---------- Seiten-Section ---------- */

main.section-white {
    background: #fff;
    padding: 40px 20px 30px;
    max-width: 1200px;
    width: 100%;
    margin: 20px auto;
}

@media (min-width: 768px) {
    main.section-white { padding: 40px 40px 30px; }
}

/* ---------- Collapsible (Basis) ---------- */

.collapsible {
    border-top: 1px solid #c8c9cb;
    overflow: hidden;
    padding: 12px 0 6px;
    position: relative;
}

.collapsible:last-child {
    border-bottom: 1px solid #c8c9cb;
}

.collapsible > h2 {
    font-size: 2.4rem;
    line-height: 1.5;
    margin: 0;
}

.collapsible-link-icon {
    display: block;
    padding-right: 60px;
    position: relative;
    text-decoration: none;
}

.collapsible-link-icon::before {
    content: "";
    position: absolute;
    right: 20px;
    top: 50%;
    width: 14px;
    height: 14px;
    margin-top: -7px;
    background: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'><path d='M2 5l5 5 5-5' fill='none' stroke='%23000' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/></svg>") no-repeat center / contain;
    transition: transform .3s ease, color .2s ease;
}

.collapsible-link-icon.collapsible-link-active::before {
    transform: rotate(180deg);
}

.collapsible-content {
    max-height: 0;
    opacity: .2;
    overflow: hidden;
    transition: max-height .3s ease, opacity .3s ease;
}

.collapsible-content p { margin-bottom: 20px; }

.collapsible-content-visible {
    max-height: 1000rem;
    opacity: 1;
}

/* ---------- Mail-Error spezifisches Styling ---------- */

.mail-error-list {
    color: #000;
    margin-bottom: 30px;
}

.mail-error-list .collapsible.mail-error-item {
    padding: 2rem;
    border-top-color: #e7e7e7;
    transition: background-color .2s ease;
}

.mail-error-list .collapsible.mail-error-item:last-child {
    border-bottom-color: #e7e7e7;
}

.mail-error-list .collapsible.mail-error-item:hover {
    background-color: #f9f9f9;
}

.mail-error-list .collapsible.mail-error-item > h2 {
    font-size: 2.0rem;
    line-height: 1.35;
    font-weight: 600;
    text-transform: none;
    letter-spacing: 0;
    margin: 0;
}

@media (min-width: 768px) {
    .mail-error-list .collapsible.mail-error-item > h2 {
        font-size: 2.4rem;
    }
}

.mail-error-list .collapsible.mail-error-item .collapsible-content h3 {
    font-size: 1.9rem;
    font-weight: 600;
    color: #000;
    margin: 18px 0 10px;
}

.mail-error-list .collapsible.mail-error-item > h2 > a.collapsible-link-icon {
    display: block;
    padding: 6px 60px 6px 4px;
    color: #000;
    text-decoration: none;
}

.mail-error-list .collapsible.mail-error-item .collapsible-link-icon::before {
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'><path d='M2 5l5 5 5-5' fill='none' stroke='%23868786' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/></svg>");
}

.mail-error-list .collapsible.mail-error-item .collapsible-link-icon:hover::before,
.mail-error-list .collapsible.mail-error-item .collapsible-link-icon.collapsible-link-active::before {
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'><path d='M2 5l5 5 5-5' fill='none' stroke='%23e4003a' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/></svg>");
}

.mail-error-title {
    display: block;
    color: #000;
    font-weight: 600;
}

.mail-error-code {
    display: inline-block;
    margin-top: 6px;
    padding: 2px 10px;
    font-family: Consolas, "SF Mono", Menlo, Monaco, "Liberation Mono", monospace;
    font-size: 1.2rem;
    font-weight: 500;
    line-height: 1.6;
    letter-spacing: 0.02em;
    color: #666;
    background: #f1f1f1;
    border-radius: 4px;
    user-select: all;
}

.mail-error-list .collapsible.mail-error-item .collapsible-content {
    padding-top: 4px;
}

.mail-error-list .collapsible.mail-error-item .collapsible-content p:first-child {
    margin-top: 8px;
}