body {
    margin: 0;
    font-family: Inter, Arial, sans-serif;
    background-color: #f4f6fb;
    color: #1f2937;
}

.top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    height: 68px;
    background-color: #ffffff;
    box-shadow: 0 1px 12px rgba(15, 23, 42, 0.08);

    position: sticky;
    top: 0;
    z-index: 1000;

    width: 100%;
    box-sizing: border-box;
}

.top-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo {
    height: 40px;
    width: auto;
}

.brand {
    font-weight: 700;
    font-size: 18px;
}

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

.lang-select {
    padding: 6px 10px;
    border-radius: 6px;
    border: 1px solid #ccc;
    background: white;
    font-size: 14px;
    cursor: pointer;
    margin-right: 20px;
}

.nav-link {
    padding: 10px 16px;
    border-radius: 8px;
    color: #1f2937;
    text-decoration: none;
    transition: background-color 0.2s ease;
}

.nav-link:hover {
    background-color: #eef2ff;
}

.hero-shell {
    max-width: 1280px;
    margin: 48px auto;
    padding: 0 24px;
    box-sizing: border-box;
}

.hero-card {
    background-color: #ffffff;
    border-radius: 24px;
    padding: 48px;
    box-shadow: 0 24px 60px rgba(15, 23, 42, 0.08);
    text-align: center;
}

.hero-card h1 {
    margin: 0;
    font-size: 3.2rem;
    line-height: 1.05;
}

.hero-card p {
    max-width: 800px;
    margin: 20px auto 30px;
    font-size: 18px;
    color: #4b5563;
    line-height: 1.7;
}

.hero-actions {
    display: inline-flex;
    align-items: center;
    gap: 14px;
    flex-wrap: wrap;
}

.primary-button,
.secondary-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 24px;
    border-radius: 10px;
    font-weight: 600;
    text-decoration: none;
}

.primary-button {
    background-color: #4f46e5;
    color: white;
}

.primary-button:hover {
    background-color: #4338ca;
}

.secondary-button {
    background-color: transparent;
    color: #4f46e5;
    border: 2px solid #4f46e5;
}

.secondary-button:hover {
    background-color: #eef2ff;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 18px;
    margin-top: 36px;
}

.stats-grid article {
    background: white;
    border-radius: 18px;
    padding: 26px;
    box-shadow: 0 16px 38px rgba(15, 23, 42, 0.06);
}

.stats-grid h2 {
    margin: 0 0 10px;
    font-size: 1.2rem;
}

.stats-grid p {
    color: #4b5563;
    line-height: 1.7;
}
/* =========================
  FEATURE CARDS
========================= */

.stats-grid {
    margin-bottom: 40px;
}

/* Each feature becomes ONE clean card */
.feature-row {
    display: flex;
    align-items: center;
    justify-content: space-between;

    gap: 48px;
    padding: 32px;

    background: white;
    border-radius: 20px;
    box-shadow: 0 18px 45px rgba(15, 23, 42, 0.06);

    width: 100%;
    box-sizing: border-box;

    min-height: 350px;
}

/* Left + right split */
.feature-demo {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    min-width: 280px;
}

.feature-text {
    flex: 1;
    min-width: 280px;
}

/* Typography consistency */
.feature-text h2 {
    font-size: 1.5rem;
    margin-bottom: 10px;
}

.feature-text p {
    color: #4b5563;
    line-height: 1.7;
    font-size: 20px;
}

/* FLASHCARD DEMO */

.mini-flashcard-container {
    width: 100%;
    max-width: 520px;
    height: 280px;
    perspective: 1200px;
}

.mini-flashcard {
    width: 100%;
    height: 100%;
    position: relative;

    transform-style: preserve-3d;
    transition: transform 0.65s ease;

    cursor: pointer;

    border-radius: 18px;
}

.mini-flashcard.flipped {
    transform: rotateY(180deg);
}

.mini-flashcard-face {
    position: absolute;
    inset: 0;

    background: white;
    border-radius: 18px;

    backface-visibility: hidden;

    box-shadow:
        0 12px 30px rgba(0,0,0,0.10);

    overflow: hidden;
}

.mini-flashcard-back {
    transform: rotateY(180deg);
}

/* FRONT */

.mini-card-title {
    position: absolute;
    top: 18px;
    left: 20px;

    font-size: 15px;
    font-weight: 700;

    color: #4f46e5;
}

.mini-card-number {
    position: absolute;
    top: 18px;
    right: 20px;

    font-size: 14px;
    color: #9ca3af;
}

.mini-card-term {
    position: absolute;

    top: 50%;
    left: 50%;

    transform: translate(-50%, -50%);

    width: 85%;

    text-align: center;

    font-size: 28px;
    font-weight: 600;

    color: #111827;
}

.mini-card-hint {
    position: absolute;

    bottom: 16px;
    left: 50%;

    transform: translateX(-50%);

    font-size: 11px;
    color: #9ca3af;
}

/* BACK */

.mini-card-content {
    padding: 55px 20px 32px;
}

.mini-info-block {
    margin-bottom: 14px;
}

.mini-info-block:last-child {
    margin-bottom: 0;
}

.mini-info-block strong {
    display: block;

    font-size: 13px;
    font-weight: 700;

    margin-bottom: 4px;

    color: #111827;
}

.mini-info-block p {
    margin: 0;

    font-size: 12px;
    line-height: 1.45;

    color: #4b5563;
}

/* =========================
   QUIZ PREVIEW
========================= */

.mini-quiz-card {
    width: 100%;
    max-width: 500px;

    background: white;

    border-radius: 20px;

    padding: 24px;

    border: 1px solid #eef2f7;

    box-shadow: 0 12px 30px rgba(0,0,0,0.05);
}

.mini-quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;

    margin-bottom: 20px;
}

.mini-section-label {
    margin: 0 0 4px;
    font-size: 11px;

    text-transform: uppercase;
    letter-spacing: 0.08em;

    color: #6b7280;
}

.mini-quiz-header h3 {
    margin: 0;
    font-size: 1.4rem;
}

.mini-term-label {
    margin: 0 0 8px;
    font-size: 14px;
    color: #4b5563;
}

.mini-term-box {
    background: #f9fafb;

    border: 1px solid #d1d5db;

    border-radius: 14px;

    padding: 18px;

    margin-bottom: 18px;

    font-weight: 600;
    font-size: 16px;
}

.mini-form {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.mini-form label {
    font-size: 14px;
    color: #4b5563;
}

.mini-form input {
    width: 100%;
    box-sizing: border-box;

    padding: 12px 14px;

    border-radius: 10px;
    border: 1px solid #d1d5db;

    background: white;

    font-size: 14px;
}

.mini-submit {
    width: 100%;
    border: none;
    border-radius: 10px;
    padding: 12px;
    background: #4f46e5;
    color: white;
    font-weight: 600;
    opacity: 0.8;
}

.demo-planner-board {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    width: 100%;
    max-width: 650px;
}

.demo-column {
    background: #ffffff;
    border: 1px solid #eef2f7;
    border-radius: 14px;
    padding: 12px;
}

.demo-column h4 {
    margin: 0 0 10px;
    font-size: 13px;
    font-weight: 600;
}

.demo-column .task-list {
    min-height: 140px;
    padding: 10px;
    border: 2px dashed #d1d5db;
    border-radius: 12px;
    background: #f8fafc;
}

.demo-column .task-card {
    background: white;
    border-radius: 10px;
    padding: 10px;
    margin-bottom: 8px;
    cursor: grab;
    border: 1px solid #e5e7eb;
    font-size: 13px;
    transition: all 0.15s ease;
}

.demo-column .task-card:hover {
    transform: translateY(-2px);
}

.demo-column .task-card.dragging {
    opacity: 0.6;
}

.demo-column .task-input-container {
    display: flex;
    gap: 8px;
    margin-top: 10px;
}

.demo-column input {
    flex: 1;
    padding: 8px;
    border-radius: 8px;
    border: 1px solid #d1d5db;
}

.demo-column button {
    padding: 8px 12px;
    border: none;
    border-radius: 8px;
    background: #4f46e5;
    color: white;
}

.demo-column input:disabled,
.demo-column button:disabled {
    opacity: 0.55;
    cursor: not-allowed;
}
/* =========================
   RESPONSIVE
========================= */

@media (max-width: 900px) {

    .hero-shell {
        margin: 24px auto;
        padding: 0 16px;
    }

    .hero-card {
        padding: 32px 24px;
    }

    .hero-card h1 {
        font-size: 2.2rem;
    }

    .hero-card p {
        font-size: 16px;
    }

    .hero-actions {
        width: 100%;
        justify-content: center;
    }

    .primary-button,
    .secondary-button {
        width: 100%;
        max-width: 280px;
    }

    .feature-row {
        flex-direction: column;
        justify-content: center;
        text-align: center;

        gap: 28px;

        min-height: auto;
        padding: 24px;
    }

    .feature-demo,
    .feature-text {
        width: 100%;
        min-width: 0;
    }

    .feature-text h2 {
        font-size: 1.3rem;
    }

    .feature-text p {
        font-size: 16px;
    }

    /* Flashcard */

    .mini-flashcard-container {
        max-width: 100%;
        height: 260px;
    }

    .mini-card-term {
        font-size: 22px;
    }

    /* Quiz */

    .mini-quiz-card {
        max-width: 100%;
        padding: 20px;
    }

    .mini-quiz-header h3 {
        font-size: 1.2rem;
    }

    /* Planner */

    .demo-planner-board {
        grid-template-columns: 1fr;
        max-width: 100%;
    }

    .demo-column {
        width: 100%;
        box-sizing: border-box;
    }

    .demo-column .task-list {
        min-height: 120px;
    }
}

@media (max-width: 600px) {

    .top-bar {
        padding: 0 16px;
    }

    .brand {
        font-size: 16px;
    }

    .nav-link {
        padding: 8px 10px;
        font-size: 14px;
    }

    .hero-card {
        padding: 24px 18px;
    }

    .hero-card h1 {
        font-size: 1.8rem;
    }

    .feature-row {
        padding: 18px;
        gap: 20px;
    }

    .mini-card-term {
        font-size: 18px;
    }

    .mini-card-content {
        padding: 50px 16px 28px;
    }

    .mini-info-block p {
        font-size: 11px;
    }

    .mini-term-box {
        font-size: 14px;
        padding: 14px;
    }

    .mini-form input,
    .mini-submit {
        font-size: 13px;
    }
}