/* ==========================================================================
   Sign AI Mentor: Clean Professional Stylesheet
   No glow. No glass. No slop.
   ========================================================================== */

/* Tokens */
:root {
    --white: #ffffff;
    --bg: #fafafa;
    --bg-alt: #f4f5f7;
    --text: #1a1a2e;
    --text-2: #484860;
    --text-3: #7c7c8d;
    --border: #e4e4ec;
    --accent: #1a6dff;
    --accent-hover: #0f52cc;
    --green: #1a7f4b;
    --green-bg: #e8f5ed;
    --red: #c4321f;
    --red-bg: #fceae7;
    --radius: 8px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* Reset */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font);
    color: var(--text);
    background: var(--white);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
}

img {
    display: block;
    max-width: 100%;
    height: auto;
}

a {
    color: inherit;
}

.container {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== HEADER ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border);
    height: 60px;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
}

.logo-img {
    width: 32px;
    height: 32px;
    border-radius: 6px;
    object-fit: contain;
}

.logo-text {
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: -0.3px;
}

.nav {
    display: flex;
    gap: 28px;
}

.nav-link {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-2);
    text-decoration: none;
    transition: color 0.15s;
}

.nav-link:hover {
    color: var(--text);
}

/* Hamburger */
.menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.menu-btn span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: transform 0.2s, opacity 0.2s;
}

.menu-btn.open span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.menu-btn.open span:nth-child(2) {
    opacity: 0;
}

.menu-btn.open span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ===== BUTTONS ===== */
.btn-solid,
.btn-outline {
    display: inline-block;
    padding: 10px 22px;
    font-size: 0.9rem;
    font-weight: 600;
    border-radius: var(--radius);
    text-decoration: none;
    transition: background 0.15s, border-color 0.15s, color 0.15s;
    cursor: pointer;
}

.btn-solid {
    background: var(--accent);
    color: var(--white);
    border: 1px solid var(--accent);
}

.btn-solid:hover {
    background: var(--accent-hover);
    border-color: var(--accent-hover);
}

.btn-outline {
    background: transparent;
    color: var(--text);
    border: 1px solid var(--border);
}

.btn-outline:hover {
    border-color: var(--text-3);
    background: var(--bg);
}

/* ===== HERO ===== */
.hero {
    padding: 120px 0 80px;
    background: var(--white);
    border-bottom: none;
}

.hero-inner {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 56px;
    align-items: center;
}

.hero-label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 12px;
}

.hero-text h1 {
    font-size: 2.6rem;
    font-weight: 700;
    line-height: 1.18;
    letter-spacing: -0.7px;
    margin-bottom: 18px;
}

.hero-desc {
    font-size: 1.05rem;
    color: var(--text-2);
    max-width: 520px;
    margin-bottom: 28px;
}

.hero-btns {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

/* Screenshot pair in hero */
.screenshot-pair {
    display: flex;
    gap: 16px;
}

.screenshot {
    position: relative;
    border-radius: 16px;
    overflow: hidden;
    border: 1px solid var(--border);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.06);
    flex: 1;
    transition: transform 0.25s ease;
}

.screenshot:hover {
    transform: translateY(-4px);
}

.screenshot img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.screenshot-label {
    position: absolute;
    top: 12px;
    left: 12px;
    padding: 3px 10px;
    border-radius: 4px;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.3px;
}

.label-green {
    background: var(--green-bg);
    color: var(--green);
}

.label-red {
    background: var(--red-bg);
    color: var(--red);
}

/* ===== SECTIONS ===== */
.section {
    padding: 80px 0;
}

.section:nth-of-type(even) {
    background: var(--bg);
}

.section-header {
    margin-bottom: 48px;
    max-width: 580px;
}

.section-header h2 {
    font-size: 1.85rem;
    font-weight: 700;
    letter-spacing: -0.4px;
    margin-bottom: 10px;
}

.section-header p {
    color: var(--text-2);
    font-size: 1rem;
}

/* ===== DEMO VIDEO ===== */
.demo-section .section-header {
    text-align: center;
    margin-left: auto;
    margin-right: auto;
}

.video-frame {
    position: relative;
    max-width: 380px;
    margin: 0 auto;
    border-radius: 16px;
    overflow: hidden;
    border: 1px solid var(--border);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.07);
    background: #000;
}

.video-frame video {
    width: 100%;
    display: block;
}

.video-play-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.25);
    cursor: pointer;
    transition: background 0.2s;
}

.video-play-overlay:hover {
    background: rgba(0, 0, 0, 0.15);
}

.video-play-overlay.hidden {
    display: none;
}

.play-icon {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--white);
    color: var(--text);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
}

/* ===== HOW IT WORKS: STEPS ===== */
.steps {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-bottom: 64px;
}

.step {
    padding: 28px 24px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.step-num {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--bg-alt);
    color: var(--text-2);
    font-weight: 700;
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 14px;
}

.step h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 6px;
}

.step p {
    color: var(--text-2);
    font-size: 0.88rem;
}

/* ===== COMPARISON ===== */
.comparison {
    border-top: 1px solid var(--border);
    padding-top: 48px;
}

.comparison-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 24px;
}

.comparison-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.comp-card {
    border: 1px solid var(--border);
    border-radius: 12px;
    overflow: hidden;
    background: var(--white);
}

.comp-card img {
    width: 100%;
    aspect-ratio: 10 / 16;
    object-fit: cover;
}

.comp-info {
    padding: 16px 20px;
    border-top: 3px solid;
}

.comp-good {
    border-color: var(--green);
}

.comp-bad {
    border-color: var(--red);
}

.comp-info strong {
    display: block;
    font-size: 0.92rem;
    margin-bottom: 4px;
}

.comp-info p {
    color: var(--text-2);
    font-size: 0.82rem;
}

/* ===== PARTNERS ===== */
.partner-section .section-header {
    text-align: center;
    margin-left: auto;
    margin-right: auto;
}

.partner-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    max-width: 720px;
    margin: 0 auto;
}

.partner-card {
    padding: 24px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    display: flex;
    flex-direction: column;
}

.partner-card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 2px;
}

.partner-meta {
    font-size: 0.78rem;
    color: var(--text-3);
    margin-bottom: 10px;
}

.partner-card>p {
    font-size: 0.88rem;
    color: var(--text-2);
    flex: 1;
}

.card-link {
    display: inline-block;
    margin-top: 14px;
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--accent);
    text-decoration: none;
}

.card-link:hover {
    text-decoration: underline;
}

/* ===== CONTACT ===== */
.contact-section {
    border-bottom: none;
}

.contact-btns {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}


/* ===== ENTRANCE ANIMATION ===== */
@keyframes fadeUp {
    from {
        opacity: 0;
        transform: translateY(16px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-text,
.hero-img-area {
    animation: fadeUp 0.5s ease both;
}

.hero-img-area {
    animation-delay: 0.1s;
}

/* ===== FOOTER ===== */
.footer {
    padding: 28px 0;
    border-top: 1px solid var(--border);
}

.footer-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.78rem;
    color: var(--text-3);
}

.footer-inner a {
    color: var(--text-3);
    text-decoration: none;
}

.footer-inner a:hover {
    color: var(--text-2);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 900px) {
    .hero-inner {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-text {
        text-align: center;
    }

    .hero-text h1 {
        font-size: 2.1rem;
    }

    .hero-desc {
        margin-left: auto;
        margin-right: auto;
    }

    .hero-btns {
        justify-content: center;
    }

    .hero-img-area {
        order: -1;
    }

    .steps {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .comparison-grid {
        grid-template-columns: 1fr;
    }

    .partner-grid {
        grid-template-columns: 1fr;
    }

    .contact-inner {
        grid-template-columns: 1fr;
        gap: 32px;
    }
}

@media (max-width: 640px) {
    .nav {
        display: none;
    }

    .nav.open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--white);
        border-bottom: 1px solid var(--border);
        padding: 20px 24px;
        gap: 16px;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
    }

    .menu-btn {
        display: flex;
    }

    .hero {
        padding: 100px 0 56px;
    }

    .hero-text h1 {
        font-size: 1.75rem;
    }

    .section {
        padding: 56px 0;
    }

    .section-header h2 {
        font-size: 1.5rem;
    }

    .screenshot-pair {
        flex-direction: column;
        gap: 12px;
    }

    .hero-btns {
        flex-direction: column;
        align-items: center;
    }

    .contact-links {
        flex-direction: column;
    }

    .footer-inner {
        flex-direction: column;
        gap: 8px;
        text-align: center;
    }
}

/* ===== WAVE DIVIDERS ===== */
.wave-container {
    position: relative;
    width: 100%;
    height: 48px;
    overflow: hidden;
    line-height: 0;
}

.wave-white-to-grey {
    background-color: var(--white);
}

.wave-grey-to-white {
    background-color: var(--bg);
}

.wave-inner {
    position: absolute;
    top: 0;
    left: 0;
    width: 150%;
    height: 150%;
    animation: waveFlow 14s linear infinite;
    will-change: transform;
}

.wave-inner svg {
    width: 100%;
    height: 100%;
    display: block;
}

.wave-fill {
    stroke: none;
}

.wave-white-to-grey .wave-fill {
    fill: var(--bg);
}

.wave-grey-to-white .wave-fill {
    fill: var(--white);
}

.wave-stroke {
    fill: none;
    stroke: var(--accent);
    stroke-width: 2.5px;
    opacity: 0.35;
}

@keyframes waveFlow {
    0% {
        transform: translate3d(0, 0, 0);
    }

    100% {
        transform: translate3d(-33.3333%, 0, 0);
    }
}

/* ===== LANGUAGE SWITCH & CAPTION ===== */
.header-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.lang-switch {
    display: flex;
    align-items: center;
    font-size: 0.78rem;
    font-weight: 600;
}

.lang-btn {
    background: none;
    border: none;
    cursor: pointer;
    padding: 2px 4px;
    color: var(--text-3);
    transition: color 0.15s;
    font-family: inherit;
    font-size: inherit;
    font-weight: inherit;
}

.lang-btn:hover,
.lang-btn.active {
    color: var(--text);
}

.lang-btn.active {
    color: var(--accent);
}

.lang-separator {
    color: var(--border);
    margin: 0 2px;
    user-select: none;
}

.dev-notice {
    font-size: 0.76rem;
    color: var(--text-3);
    text-align: center;
    margin-top: 14px;
    line-height: 1.4;
}

/* Hide inactive language elements */
html:not([lang="en"]) .lang-en {
    display: none !important;
}

html[lang="en"] .lang-de {
    display: none !important;
}