:root {
    --midnight-ink: #000000;
    --canvas-white: #ffffff;
    --whisper-gray: #f6f6f6;
    --charcoal-text: #333333;
    --input-border-gray: #767676;
    --subtle-silver: #afafaf;
    --lagoon-mist: #9dcdd6;
}

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

html, body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    background-color: var(--canvas-white);
    color: var(--charcoal-text);
    line-height: 1.5;
}

body {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1;
}

h1, h2, h3, h4, h5, h6 {
    color: var(--midnight-ink);
    font-weight: 600;
    margin-bottom: 16px;
}

h1 { font-size: 52px; }
h2 { font-size: 36px; }
h3 { font-size: 24px; }
h4 { font-size: 20px; }

p { margin-bottom: 16px; }

a { color: var(--midnight-ink); text-decoration: none; }
a:hover { opacity: 0.7; }

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    width: 100%;
}

.section {
    padding: 60px 0;
}

header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--canvas-white);
    border-bottom: 1px solid var(--whisper-gray);
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 24px;
    height: 60px;
}

.logo {
    font-size: 24px;
    font-weight: 700;
    color: var(--midnight-ink);
}

nav {
    display: flex;
    gap: 24px;
    align-items: center;
}

nav a {
    font-size: 16px;
}

.nav-right {
    display: flex;
    gap: 12px;
    align-items: center;
}

.btn {
    display: inline-block;
    padding: 14px 25px;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    text-align: center;
    transition: all 0.2s;
}

.btn-primary {
    background-color: var(--midnight-ink);
    color: var(--canvas-white);
}

.btn-primary:hover {
    background-color: var(--charcoal-text);
}

.btn-secondary {
    background-color: var(--whisper-gray);
    color: var(--midnight-ink);
    border: 1px solid var(--input-border-gray);
}

.btn-capsule {
    padding: 10px 16px;
    border-radius: 999px;
    background-color: var(--midnight-ink);
    color: var(--canvas-white);
}

.btn-ghost {
    background-color: transparent;
    color: var(--midnight-ink);
    border: 1px solid var(--input-border-gray);
    padding: 10px 16px;
    border-radius: 999px;
}

input[type="text"],
input[type="email"],
input[type="password"],
textarea {
    width: 100%;
    padding: 12px 0;
    background-color: transparent;
    border: none;
    border-bottom: 1px solid var(--input-border-gray);
    font-size: 16px;
    font-family: inherit;
    color: var(--midnight-ink);
}

input:focus,
textarea:focus {
    outline: none;
    border-bottom-color: var(--midnight-ink);
}

input::placeholder,
textarea::placeholder {
    color: var(--subtle-silver);
}

.form-group {
    margin-bottom: 24px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 600;
}

.card {
    background-color: var(--canvas-white);
    border-radius: 8px;
    padding: 24px;
    border: 1px solid var(--whisper-gray);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
    transition: all 0.3s;
}

.card:hover {
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.12);
    transform: translateY(-4px);
}

.grid {
    display: grid;
    gap: 24px;
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }

.course-card {
    background-color: var(--canvas-white);
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--whisper-gray);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
    transition: all 0.3s;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
}

.course-card:hover {
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.12);
    transform: translateY(-4px);
}

.course-image {
    width: 100%;
    height: 180px;
    background-color: var(--whisper-gray);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 48px;
    border-bottom: 1px solid var(--whisper-gray);
    overflow: hidden;
}

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

.course-body {
    padding: 24px;
}

.course-category {
    display: inline-block;
    padding: 4px 8px;
    background-color: var(--lagoon-mist);
    color: var(--midnight-ink);
    border-radius: 4px;
    font-size: 11px;
    font-weight: 600;
    margin-bottom: 12px;
}

.course-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
}

.course-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--whisper-gray);
    font-size: 12px;
}

footer {
    background-color: var(--midnight-ink);
    color: var(--canvas-white);
    padding: 60px 24px;
    margin-top: 60px;
}

footer .container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 24px;
    margin-bottom: 24px;
}

footer h4 {
    color: var(--canvas-white);
    margin-bottom: 16px;
    font-size: 16px;
}

footer a {
    color: var(--canvas-white);
    font-size: 14px;
    line-height: 1.8;
    opacity: 0.8;
}

footer a:hover {
    opacity: 1;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 24px;
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: rgba(255, 255, 255, 0.6);
}

.hero {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    min-height: 500px;
}

.hero-visual {
    background-color: var(--whisper-gray);
    border-radius: 12px;
    padding: 60px;
    min-height: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 100px;
}

.tab-btn {
    padding: 16px 0;
    background: none;
    border: none;
    color: var(--subtle-silver);
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    border-bottom: 2px solid transparent;
    margin-right: 24px;
}

.tab-btn.active {
    color: var(--midnight-ink);
    border-bottom-color: var(--midnight-ink);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.profile-tabs {
    display: flex;
    gap: 24px;
    margin-bottom: 60px;
    border-bottom: 1px solid var(--whisper-gray);
}

@media (max-width: 768px) {
    header .container {
        flex-direction: column;
        height: auto;
        gap: 12px;
    }
    
    nav {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 12px;
    }
    
    .hero {
        grid-template-columns: 1fr;
        gap: 24px;
        min-height: auto;
    }
    
    h1 { font-size: 32px; }
    h2 { font-size: 24px; }
    
    .grid-2, .grid-3 {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }
    
    .btn {
        padding: 10px 14px;
        font-size: 12px;
    }
    
    h1 { font-size: 24px; }
    h2 { font-size: 20px; }
}