/* ==========================================
   1. TEEMAMUUTTUJAT (Light / Dark Mode)
   ========================================== */
:root, html[data-theme="light"] {
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --card-bg: #f5f5f5;
    --accent-color: #0066cc;
    --nav-bg: #f8f9fa;
    --border-color: rgba(0, 0, 0, 0.08);
    --hover-bg: rgba(0, 0, 0, 0.04);
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

html[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #f5f5f5;
    --card-bg: #1e1e1e;
    --accent-color: #4da3ff;
    --nav-bg: #1a1a1a;
    --border-color: rgba(255, 255, 255, 0.08);
    --hover-bg: rgba(255, 255, 255, 0.05);
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

/* ==========================================
   2. YLEISET TYYLIT & POHJA
   ========================================== */
body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    transition: background-color 0.25s ease, color 0.25s ease;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* ==========================================
   3. MODERNIN NAVIGAATIOPALKKI (Navbar)
   ========================================== */
header {
    background-color: var(--nav-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color 0.25s ease, border-color 0.25s ease;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1000px;
    margin: 0 auto;
    padding: 0.75rem 1.5rem;
}

/* Logo */
.logo a {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-color);
    text-decoration: none;
    letter-spacing: -0.5px;
    transition: color 0.2s ease;
}

.logo a:hover {
    color: var(--accent-color);
}

/* Navigaatiolista suoraksi riviksi */
nav ul {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin: 0;
    padding: 0;
}

/* Navigaatiolinkit näyttämään painikkeilta */
nav a[data-link] {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.6rem 1rem;
    border-radius: 6px;
    transition: all 0.2s ease;
    opacity: 0.85;
}

nav a[data-link]:hover {
    background-color: var(--hover-bg);
    color: var(--accent-color);
    opacity: 1;
}

/* Aktiivisen sivun tyyli */
nav a[data-link].active {
    background-color: rgba(0, 102, 204, 0.1);
    color: var(--accent-color);
    font-weight: 600;
    opacity: 1;
}

html[data-theme="dark"] nav a[data-link].active {
    background-color: rgba(77, 163, 255, 0.15);
}

/* Teemanvaihtonappi */
#lang-toggle {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    padding: 0.6rem;
    border-radius: 5px;
    transition: background-color 0.2s;
}

#lang-toggle:hover {
    background-color: var(--hover-bg);
}

#lang-toggle [data-lang-option] {
    opacity: 0.5;
}

#lang-toggle [data-lang-option].active {
    opacity: 1;
    color: var(--accent-color);
}

#theme-toggle {
    background: none;
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    padding: 0.6rem;
    border-radius: 5px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s, transform 0.2s;
}

#theme-toggle:hover {
    background-color: var(--hover-bg);
    transform: scale(1.08);
}

/* ==========================================
   4. SPA-REITITTIMEN NÄKYVYYS & ANIMAATIOT
   ========================================== */
.page-view {
    display: none; /* Piilotetaan kaikki sivut oletuksena */
    animation: fadeIn 0.25s ease-in-out;
}

.page-view.active {
    display: block; /* Näytetään vain aktiivinen sivu */
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ==========================================
   5. SISÄLTÖALUEET JA SIVUJEN ASETTELUT
   ========================================= */
main {
    flex: 1;
}

.content-container {
    max-width: 800px;
    margin: 3rem auto;
    padding: 0 1.5rem;
}

/* Etusivun Hero-elementti */
.hero {
    max-width: 800px;
    margin: 4rem auto;
    padding: 5rem 2rem;
    text-align: center;
    background-color: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow);
    transition: background-color 0.25s ease, box-shadow 0.25s ease;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

/* Yhteystietosivu & Kortit (Contact) */
.contact-container {
    max-width: 500px;
    margin: 4rem auto;
    padding: 0 1.5rem;
}

.contact-card {
    background-color: var(--card-bg);
    padding: 2.5rem;
    border-radius: 10px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    transition: all 0.25s ease;
}

.contact-method {
    margin-top: 1.8rem;
    border-top: 1px solid var(--border-color);
    padding-top: 1.2rem;
}

.contact-method h3 {
    margin: 0 0 0.5rem 0;
    font-size: 1.1rem;
    opacity: 0.9;
}

.contact-method p {
    margin: 0;
}

.contact-method a {
    color: var(--accent-color);
    text-decoration: none;
    font-size: 1.2rem;
    font-weight: 500;
    transition: opacity 0.2s ease;
}

.contact-method a:hover {
    text-decoration: underline;
    opacity: 0.85;
}

/* ==========================================
   6. ALATUNNISTE (Footer)
   ========================================== */
footer {
    text-align: center;
    padding: 2.5rem;
    font-size: 0.9rem;
    opacity: 0.6;
    border-top: 1px solid var(--border-color);
    background-color: var(--nav-bg);
    transition: background-color 0.25s ease, border-top 0.25s ease;
}

/* ==========================================
   7. RESPONSIIVISUUS (Mobiilimukautus)
   ========================================== */
@media (max-width: 600px) {
    nav {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    
    nav ul {
        width: 100%;
        justify-content: center;
        gap: 0.25rem;
    }
    
    nav a[data-link] {
        padding: 0.5rem 0.75rem;
        font-size: 0.9rem;
    }
    
    .hero {
        margin: 2rem 1rem;
        padding: 3rem 1rem;
    }
    
    .hero h1 {
        font-size: 1.8rem;
    }
}

.course-category {
    margin-top: 2rem;
}

.course-card {
    margin: 1rem 0;
    padding: 1rem 1.25rem;
    border: 1px solid rgba(128, 128, 128, 0.35);
    border-radius: 8px;
}

.course-links {
    list-style: none;
    padding: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}