/* --- CSS Variables --- */
:root {
    --color-background: #111827;
    --color-surface: #1f2937;
    --color-primary: #ec4899; /* brand-pink */
    --color-secondary: #f59e0b; /* brand-yellow */
    --color-text: #d1d5db;
    --color-text-muted: #9ca3af;
    --color-border: #374151;
    --font-family-sans: 'Inter', sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family-sans);
    background-color: var(--color-background);
    color: var(--color-text);
    line-height: 1.6;
    overflow-x: hidden;
}

/* --- Typography & Links --- */
h1, h2, h3, h4 {
    line-height: 1.2;
    font-weight: 700;
}

h1 { font-size: clamp(2rem, 3vw + 1rem, 3.25rem); font-weight: 800; }
h2 { font-size: clamp(1.5rem, 2vw + 1rem, 2.5rem); }
h3 { font-size: 1.25rem; }

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.3s ease;
}
a:hover {
    color: #fce7f3;
}

/* --- Layout --- */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.25rem;
}

section {
    padding: 6rem 0;
    scroll-margin-top: 90px; /* offset for fixed header when using hash links */
}

/* --- Header --- */
.site-header {
    position: fixed;
    width: 100%;
    padding: 1.5rem 0;
    z-index: 100;
    background: rgba(17, 24, 39, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: #fff;
}

.site-header .main-nav {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

/* --- Language Switcher --- */
.language-switcher {
    position: relative;
    margin-left: 1rem;
}
.language-switcher summary {
    list-style: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem;
    border-radius: 8px;
    transition: background-color 0.2s ease;
}
.language-switcher summary::-webkit-details-marker {
    display: none;
}
.language-switcher summary:hover {
    background-color: var(--color-surface);
}
.language-switcher summary img {
    width: 24px;
    height: 24px;
    stroke: var(--color-text-muted);
}
.language-switcher[open] summary {
    background-color: var(--color-surface);
}

.language-options {
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    background: rgba(31, 41, 55, 0.9);
    backdrop-filter: blur(10px);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 0.5rem;
    width: max-content;
    z-index: 101;
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}
.language-options button {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    width: 100%;
    background: none;
    border: none;
    color: var(--color-text);
    padding: 0.75rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    text-align: left;
    font-size: 0.9rem;
    transition: background-color 0.2s ease;
}
.language-options button:hover {
    background-color: rgba(236, 72, 153, 0.2);
    color: #fff;
}


/* --- Buttons --- */
.button {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-weight: 700;
    cursor: pointer;
    text-align: center;
    transition: transform 0.3s ease, background-color 0.3s ease;
}
.button:hover {
    transform: translateY(-3px);
}

.button-primary {
    background-color: var(--color-primary);
    color: #fff;
}
.button-primary:hover {
    background-color: #f9a8d4;
    color: var(--color-background);
}

.button-secondary {
    background-color: transparent;
    border: 2px solid var(--color-secondary);
    color: var(--color-secondary);
}
.button-secondary:hover {
    background-color: var(--color-secondary);
    color: var(--color-background);
}


/* --- Hero Section --- */
.hero {
    min-height: calc(100vh - 72px);
    display: flex;
    align-items: center;
    text-align: center;
    padding-top: 7rem; /* header offset */
    position: relative;
}

.hero .container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
}

.hero-title {
    color: #fff;
    text-shadow: 0 0 20px rgba(236, 72, 153, 0.3);
}

.hero-tagline {
    font-size: clamp(1rem, 1.2vw + 0.8rem, 1.25rem);
    color: var(--color-text-muted);
    max-width: 720px;
}

.background-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.background-animation::before,
.background-animation::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.15;
    animation: orbit 30s linear infinite;
}

.background-animation::before {
    width: 400px;
    height: 400px;
    background: var(--color-primary);
    top: 10vh;
    left: 10vw;
}

.background-animation::after {
    width: 300px;
    height: 300px;
    background: var(--color-secondary);
    bottom: 10vh;
    right: 10vw;
    animation-direction: reverse;
    animation-duration: 25s;
}

@keyframes orbit {
    0% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(20vw, 10vh) scale(1.1); }
    50% { transform: translate(0, 20vh) scale(0.9); }
    75% { transform: translate(-20vw, 10vh) scale(1.2); }
    100% { transform: translate(0, 0) scale(1); }
}


/* --- Section Titles --- */
.section-title {
    text-align: center;
    color: #fff;
    margin-bottom: 1rem;
}
.section-subtitle {
    text-align: center;
    color: var(--color-text-muted);
    max-width: 700px;
    margin: 0 auto 3rem auto;
}

/* --- About Section --- */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 4rem;
}
.feature-item {
    background-color: var(--color-surface);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    border: 1px solid var(--color-border);
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
}
.feature-icon {
    margin-bottom: 1.5rem;
}
.feature-icon img {
    height: 48px;
    width: 48px;
    filter: drop-shadow(0 0 10px rgba(236, 72, 153, 0.2));
}
.feature-title {
    color: #fff;
    margin-bottom: 0.5rem;
}

/* --- Why It Matters Section --- */
.why-section {
    background: linear-gradient(180deg, var(--color-background) 0%, var(--color-surface) 50%, var(--color-background) 100%);
}
.why-container {
    display: grid;
    grid-template-columns: 1fr;
    align-items: center;
    gap: 3rem;
}
.why-content p {
    margin-bottom: 1rem;
    color: var(--color-text-muted);
}
.why-content p:last-child {
    margin-bottom: 0;
}
.why-content strong {
    color: var(--color-text);
}
.why-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}
.mockup-app {
    background-color: #0d121c;
    border-radius: 12px;
    padding: 1.5rem;
    width: 100%;
    max-width: 400px;
    border: 1px solid var(--color-border);
    box-shadow: 0 20px 40px rgba(0,0,0,0.3);
}
.mockup-app h4 {
    color: #fff;
    margin-bottom: 1.5rem;
    text-align: center;
}
.mockup-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--color-surface);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    margin-bottom: 0.75rem;
    font-size: 0.9rem;
}
.mockup-item .dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
}
.mockup-item.fertile .dot { background-color: #14b8a6; } /* teal */
.mockup-item.period .dot { background-color: #ef4444; } /* red */
.mockup-item.mood .dot { background-color: #3b82f6; } /* blue */
.mockup-item.best-time .dot { background-color: #f59e0b; } /* yellow */


/* --- Visual Teaser Section --- */
.teaser-section {
    background-image: radial-gradient(circle at 20% 80%, rgba(236, 72, 153, 0.1), transparent 30%),
                      radial-gradient(circle at 80% 30%, rgba(245, 158, 11, 0.1), transparent 30%);
    min-height: 40vh;
    display: flex;
    align-items: center;
    justify-content: center;
}
.teaser-section .section-title {
    max-width: 600px;
    margin: 0 auto;
}

/* --- Signup Section --- */
.signup-section {
    background-color: var(--color-surface);
}
.signup-container {
    max-width: 600px;
}
.newsletter-form {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}
.newsletter-form input {
    flex-grow: 1;
    padding: 0.75rem 1rem;
    border-radius: 8px;
    border: 1px solid var(--color-border);
    background-color: var(--color-background);
    color: var(--color-text);
    font-size: 1rem;
}
.newsletter-form input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(236, 72, 153, 0.3);
}
.form-success {
    text-align: center;
    margin-top: 1rem;
    color: var(--color-secondary);
}

/* --- Footer --- */
.site-footer {
    padding: 2rem 0;
    text-align: center;
    color: var(--color-text-muted);
    font-size: 0.9rem;
    border-top: 1px solid var(--color-border);
}

/* --- Reveal on Scroll Animation --- */
.reveal {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

.hero .reveal:nth-child(1) { transition-delay: 0.1s; }
.hero .reveal:nth-child(2) { transition-delay: 0.2s; }
.hero .reveal:nth-child(3) { transition-delay: 0.3s; }
.features-grid .reveal:nth-child(1) { transition-delay: 0.1s; }
.features-grid .reveal:nth-child(2) { transition-delay: 0.2s; }
.features-grid .reveal:nth-child(3) { transition-delay: 0.3s; }

/* --- Responsive Styles --- */
@media (min-width: 768px) {
    .container { max-width: 1200px; }
    .why-container { grid-template-columns: 1fr 1fr; }
    .why-content { text-align: left; }
    .why-content .section-title,
    .why-content .section-subtitle {
        text-align: left;
        margin-left: 0;
        margin-right: 0;
    }
}

@media (max-width: 768px) {
    .site-header .main-nav a:not(.button) {
        display: none;
    }
    .newsletter-form {
        flex-direction: column;
    }
    .hero { padding-top: 6.5rem; }
}

@media (min-width: 1280px) {
    .container { max-width: 1280px; }
}